EP4662226A1

EP4662226A1 - Therapeutic molecules comprising variants of the extracellular domain of p75 neurotrophin receptor (p75ntr)

Info

Publication number: EP4662226A1
Application number: EP24706791.1A
Authority: EP
Inventors: Marco BARDELLI
Original assignee: Zoetis Services UK Ltd
Current assignee: Zoetis Services UK Ltd
Priority date: 2023-02-09
Filing date: 2024-02-09
Publication date: 2025-12-17
Also published as: AU2024217925A1; MX2025009341A; KR20250141832A; WO2024165872A1; CN120712277A; CO2025011662A2; JP2026511340A

Abstract

The present invention relates to effective therapies for pain, inflammation and osteoarthritis, especially in companion animals, like dogs. The invention provides an isolated polypeptide comprising a variant p75 neurotrophin receptor (p75NTR) extracellular domain or a fusion protein containing the same or portions thereof, especially to an Fc domain. Nucleic acids encoding the proteins are also encompassed in the invention as well as methods of using the same.

Description

THERAPEUTIC MOLECULES RELATED APPLICATIONS AND INCORPORATION BY REFERENCE [0001] This application claims the benefit of priority from GB Application No. 2301838.5 (filed February 9, 2023), GB Application No. 2301839.3 (filed February 9, 2023), US Application No. 18/187,377 (filed March 21, 2023) and US Application No. 18/187,414 (filed March 21, 2023). [0002] All documents cited or referenced herein (“herein cited documents”), and all documents cited or referenced in herein cited documents, together with any manufacturer’s instructions, descriptions, product specifications, and product sheets for any products mentioned herein or in any document incorporated by reference herein, are hereby incorporated herein by reference, and may be employed in the practice of the invention. More specifically, all referenced documents are incorporated by reference to the same extent as if each individual document was specifically and individually indicated to be incorporated by reference. SEQUENCE STATEMENT [0003] The instant application contains a Sequence Listing, which has been submitted electronically and is hereby incorporated by reference in its entirety. Said XML copy, was created February 01, 2024, is named P44829WO1 SL.xml and is 194,555 bytes in size. FIELD OF THE INVENTION [0004] The present invention relates to effective pain therapies in humans and companion animals. BACKGROUND OF THE INVENTION [0005] There is a huge need for therapies for pain relief. Moreover, there is a need for effective pain treatments with minimal side effects. [0006] Pain relief treatments currently include nonsteroidal anti-inflammatory drugs (NSAIDs), and with several nonsteroidal anti-inflammatory drugs which help to control pain and inflammation associated with osteoarthritis. Several NSAIDs have been approved by the FDA. However, there is a need for further effective pain treatments with minimal side effects. [0007] Neurotrophins are a family of proteins involved in proliferation, maintenance, and survival of neurons. Since nerve growth factor (NGF) was discovered in 1950s, numerous biological processes involving NGF have been identified. NGF is critical for proliferation and maintenance of neurons and also plays a role in inflammation and maintenance of pancreatic beta cells. NGF binds to least two receptors, tropomyosin receptor kinase A (TrkA) and low-affinity NGF receptor (LNGFR/p75NTR). The neurotrophin family also includes structurally related brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4) (also known as NT-5 or NT-4/5). BDNF and NT-4 function primarily through tropomyosin receptor kinase B (TrkB). NT-3 binds with high affinity to tropomyosin receptor kinase C (TrkC) but also is capable of signaling through TrkB. All four neurotrophins bind with low affinity to p75NTR. [0008] NGF causes peripheral sensitization both in vitro and in vivo, as illustrated by the increased response of DRG neurons to temperature or capsaicin in its presence. NGF also leads to transcriptional regulation after retrograde axonal transport, as illustrated by immunostaining showing upregulation of BDNF after intrathecal NGF treatment. Furthermore, NGF can cause sprouting of peripheral afferents into diseased joints and cancerous tissue (Denk et al, Annual Review of Neuroscience, Vol. 40:307-325, 2017). [0009] NGF is expressed at low levels in adulthood, but injury, inflammation or release of NGF cause activation of inflammatory cells. These cells in turn produce and secrete NGF as well and this leads to short-term and long-term effects. NGF has a well-known and multifunctional role in nociceptive processing, although the precise signaling pathways downstream of NGF receptor activation that mediate nociception are complex and not completely understood. The role of NGF in nociception and the generation and/or maintenance of chronic pain has led to it becoming an attractive target of pain therapeutics for the treatment of chronic pain conditions (Barker et al, Journal of Pain Research, 2020:131223–1241). [0010] Very low doses of monoclonal antibodies (mAbs) directed against NGF can reduce chronic pain. However, during clinical trials in humans, a small subset of patients treated with mAbs directed against NGF developed rapidly progressive joint degeneration due to interaction with NSAIDs treatment. Complete NGF removal is shown to cause impaired bone and cartilage repairing (Denk et al, Annual Review of Neuroscience, Vol. 40:307-325, 2017). Treatments for use in dogs and cats based on species-specific mAbs that target NGF are now being developed for the management of osteoarthritis (OA)-associated pain (Enomoto et al, Vet Rec. 2019 Jan 5;184(1):23 and WO2019177690). However, given the side effects that occurred in clinical trials in humans, there is a need to develop alternative treatments that target NGF. [0011] Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention. SUMMARY OF THE INVENTION [0012] There is a need for effective pain therapies in humans and companion animals. The invention provides a pain therapy with reduced side effects compared to anti-NGF antibody therapies. The proteins of the invention bind NGF which is at elevated levels in pain conditions, thus binding to excess NGF to restore normal NGF levels without completely blocking NGF signalling. Without wishing to be bound by theory, the inventors believe that this ensures a level of NGF signalling which is required for healthy functions. Furthermore, it is believed that the fusion proteins of the invention can operate at a very low dose, but are highly efficacious. [0013] The inventors have used an analgesic strategy to reduce, but not completely deplete, NGF in circulation. To this end, the Extracellular Domain (ECD) of p75 neurotrophin receptor (p75NTR) was used, fused to an Fc to increase its half-life. p75NTR binds NGF, pro- NGF and other brain-derived neurotrophic factors (BDNF, NT3, NT4) and mediates different cellular activities. The inventors have further used a structure guided mutation strategy to generate p75NTR variants with advantageous physiochemical properties. Point mutations have been introduced into the extracellular domain of p75NTR and used to modulate the binding affinity of p75NTR to its ligand NGF. These variant p75NTR molecules have altered binding characteristics compared to wild-type p75NTR which may allow efficient binding of NGF without completely removing NGF which has been shown to lead to negative side effects such as joint deterioration. [0014] In a first aspect the invention relates to an isolated polypeptide comprising a p75 neurotrophin receptor (p75NTR) extracellular domain, wherein said p75NTR extracellular domain comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134. [0015] The invention also relates to an isolated nucleic acid encoding the isolated polypeptide comprising a p75NTR extracellular domain, wherein said p75NTR extracellular domain comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134. [0016] The invention also relates to a vector comprising a nucleic acid described above. [0017] The invention also relates to a host cell comprising a nucleic acid described above or a vector as described above. [0018] An aspect of the invention relates to a fusion protein comprising a p75NTR extracellular domain, wherein said p75NTR extracellular domain comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134, and a half-life extending moiety. [0019] The invention also relates to nucleic acid encoding a fusion protein as described above. [0020] The invention also relates to a vector comprising a nucleic acid encoding a fusion protein as described above. [0021] The invention also relates to a host cell comprising a nucleic acid encoding a fusion protein as described above, or a vector comprising a nucleic acid encoding a fusion protein as described above. [0022] An aspect of the invention relates to a pharmaceutical composition comprising an isolated polypeptide as described above and herein or a fusion protein as described above and herein. [0023] An aspect of the invention relates to a method for treating an NGF-related disorder in a subject comprising administering an isolated p75NTR protein as described above and herein, a fusion protein as described above and herein, or a pharmaceutical composition as described above and herein. [0024] An aspect of the invention relates to the use of an isolated p75NTR protein as described above and herein, a fusion protein as described above and herein, or a pharmaceutical composition as described above and herein in the treatment of an NGF-related disorder in a subject. [0025] An aspect of the invention relates to an isolated p75NTR protein as described above and herein, or a fusion protein as described above and herein for use in the treatment of an NGF-related disorder in a subject. [0026] An aspect of the invention relates to a method of inhibiting NGF activity in a subject comprising administering an isolated p75NTR protein as described above and herein, a fusion protein as described above and herein, or a pharmaceutical composition as described above and herein. [0027] An aspect of the invention relates to a kit comprising an isolated p75NTR protein as described above and herein, a fusion protein as described above and herein, or a pharmaceutical composition as described above and herein and optionally instructions for use. [0028] In certain embodiments, the p75NTR is from a human. In certain embodiments, the p75NTR is from a non-human primate. In certain embodiments, the p75NTR is from an animal. In certain embodiments, the p75NTR is from a companion animal, including but not limited to a dog, a cat, a horse, a cow, a sheep, or a camel. [0029] In certain embodiments, an isolated p75NTR protein of the invention is used to treat or to inhibit NGF activity in a human. In certain embodiments, an isolated p75NTR protein of the invention is used to treat or to inhibit NGF activity in a non-human primate. In certain embodiments, an isolated p75NTR protein of the invention may be used to treat or to inhibit NGF activity in an animal. In certain embodiments, an isolated p75NTR protein of the invention may be used to treat or to inhibit NGF activity in a companion animal. [0030] An aspect of the invention relates to the treatment of osteoarthritis using an isolated p75NTR protein. In certain embodiments, an isolated p75NTR protein described herein is used to treat or prevent osteoarthritis in a human. In certain embodiments, an isolated p75NTR protein described herein is used to treat or prevent osteoarthritis in a non-human primate. In certain embodiments, an isolated p75NTR protein described herein may be used to treat or prevent osteoarthritis in an animal. In certain embodiments, an isolated p75NTR protein described herein may be used to treat or prevent osteoarthritis in a companion animal. In certain embodiments the method may comprise slowing or arresting of disease progression, reversal of disease progression, regrowth of cartilage and/or curative treatment. In certain embodiments the method may be determined by the rate of cartilage loss or regrowth. In certain embodiments treatment of osteoarthritis may comprise slowing or arresting of disease progression, reversal of disease progression, regrowth of cartilage and/or curative treatment. In certain embodiments the treatment may be determined by the rate of cartilage loss or regrowth. In certain embodiments the treatment of osteoarthritis may comprise slowing or arresting of disease progression, reversal of disease progression, regrowth of cartilage and/or curative treatment. In certain embodiments the treatment may be determined by the rate of cartilage loss or regrowth. [0031] Accordingly, it is an object of the invention not to encompass within the invention any previously known product, process of making the product, or method of using the product such that Applicants reserve the right and hereby disclose a disclaimer of any previously known product, process, or method. It is further noted that the invention does not intend to encompass within the scope of the invention any product, process, or making of the product or method of using the product, which does not meet the written description and enablement requirements of the USPTO (35 U.S.C. §112, first paragraph) or the EPO (Article 83 of the EPC), such that Applicants reserve the right and hereby disclose a disclaimer of any previously described product, process of making the product, or method of using the product. It may be advantageous in the practice of the invention to be in compliance with Art. 53(c) EPC and Rule 28(b) and (c) EPC. All rights to explicitly disclaim any embodiments that are the subject of any granted patent(s) of applicant in the lineage of this application or in any other lineage or in any prior filed application of any third party is explicitly reserved. Nothing herein is to be construed as a promise. [0032] It is noted that in this disclosure and particularly in the claims and/or paragraphs, terms such as “comprises,” “comprised,” “comprising” and the like can have the meaning attributed to it in U.S. Patent law; e.g., they can mean “includes,” “included,” “including,” and the like; and that terms such as “consisting essentially of” and “consists essentially of” have the meaning ascribed to them in U.S. Patent law, e.g., they allow for elements not explicitly recited, but exclude elements that are found in the prior art or that affect a basic or novel characteristic of the invention. [0033] These and other embodiments are disclosed or are obvious from and encompassed by, the following Detailed Description. BRIEF DESCRIPTION OF THE DRAWINGS [0034] The invention is described in the following non-limiting figures. [0035] Figure 1. Sequence alignment of human (SEQ ID NO:73), canine (SEQ ID NO:7), feline (SEQ ID NO:38), equine (SEQ ID NO:5), camel (SEQ ID NO:101), bovine (SEQ ID NO:36), and porcine (SEQ ID NO:110) p75NTR extracellular domains. Amino acids 1-160 are shown. The stalk region and alpha and gamma secretase cleavage sites are not depicted. Sequence alignment performed using EXPASY Clustal Omega. Mutated residues according to the invention are indicated by boxes. [0036] Figure 2. 3D model of canine p75NTR-ECD (shown as cartoon with transparent surface) in complex with canine NGF (Shown as cartoon) based generated using homology modelling to human pdb 1SG1. Circled are residues of p75NTR-ECD important for binding to NGF. [0037] Figure 3. Binding affinity of p75NTR variants. Each panel represents a representative SPR sensogram (showing both raw data as dots and fitted data using 1:1 Langmuir fitting as lines) including 5 different concentrations of PetML119wt, variants and Bedinvetmab. Table 1 shows kinetics values obtained from the fitting. [0038] Figure 4. Thermal stability analysis of p75NTR variants. Intrinsic fluorescence measurements obtained from each molecule are shown in the graph. Calculated Tm for these molecules is provided in a summary table in Figure 4. [0039] Figure 5. TF-1 cell proliferation assay. In Y-axis Mean Fluorescence Intensity values normalised to controls are shown while in X-axis are shown concentration of either PetML119wt, variants or Bedinvetmab used. Fitted curves using a sigmoidal function are shown as well as IC50 and ICMAX values derived from this for each molecule tested. [0040] Figure 6. TrkA activation assay. In Y-axis Luminescence AU values normalised to controls are shown while in X-axis are shown concentration of either PetML119wt, variants or Bedinvetmab used. Fitted curves using a sigmoidal function are shown as well as IC50 and ICMAX values derived from this for each molecule tested. [0041] Figure 7. Schematic of in vivo study. [0042] Figure 8. Human and rat Nerve Growth Factor (h-rNGF) binding affinity determination. Each panel represents a representative SPR sensogram (showing both raw data as dots and fitted data using 1:1 Langmuir fitting as lines) including 5 different concentrations of PetML308, PetML309 and PetML319. Table 6 and 7 shows kinetics values obtained from fitting. [0043] Figure 9. Thermal denaturation by UnCle. Intrinsic fluorescence measurements obtained from each molecule are shown in the graph for each tested molecule. Table 8 shows the melting temperatures for each molecule. [0044] Figure 10. TrkA activation assay. In Y-axis Luminescence AU values normalised to controls are shown while in X-axis are shown concentration of either PetML308, PetML309 and PetML319 used. Fitted curves using a sigmoidal function as well as IC50 and ICMAX values derived from this for each molecule tested. [0045] Figure 11. Analgesic effects in vivo. Dynamic weight bearing analysis of rats using a monosodium-iodoacetate (MIA) osteoarthritis model. Figure 11A Day 3. Figure 11B Day 6. Figure 11C Day 14. Figure 11D Day 21. [0046] Figure 12. pK analysis of rats using an MIA osteoarthritis model. Figure 12A. Plasma p75-Fc pK. Figure 12B. Plasma NGF. [0047] Figure 13. Joint diameter measurements using an MIA osteoarthritis model. [0048] Figure 14. anti-inflammatory investigation of p75NTR-Fc molecules in DH82 cell line [0049] Figure 15. Disease-modifying osteoarthritis drug (DMOAD) in rats. DETAILED DESCRIPTION OF THE INVENTION [0050] The present invention will now be further described. In the following passages, different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous. [0051] Generally, nomenclatures used in connection with, and techniques of, cell and tissue culture, pathology, oncology, molecular biology, immunology, microbiology, genetics and protein and nucleic acid chemistry and hybridization described herein are those well-known and commonly used in the art. The methods and techniques of the present disclosure are generally performed according to conventional methods well-known in the art and as described in various general and more specific references that are cited and discussed throughout the present specification unless otherwise indicated. See, e.g., Green and Sambrook et al., Molecular Cloning: A Laboratory Manual, 4th ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (2012); Therapeutic Monoclonal Antibodies: From Bench to Clinic, Zhiqiang An (Editor), Wiley, (2009); and Antibody Engineering, 2nd Ed., Vols.1 and 2, Ontermann and Duebel, eds., Springer- Verlag, Heidelberg (2010). [0052] Enzymatic reactions and purification techniques are performed according to manufacturer’s specifications, as commonly accomplished in the art or as described herein. The nomenclatures used in connection with, and the laboratory procedures and techniques of, analytical chemistry, synthetic organic chemistry, and medicinal and pharmaceutical chemistry described herein are those well-known and commonly used in the art. Standard techniques are used for chemical syntheses, chemical analyses, pharmaceutical preparation, formulation, and delivery, and treatment of patients. [0053] The invention provides biological therapeutics for human and veterinary use, including p75NTR fusion proteins for use in the treatment of human or companion animals such as dogs, cats, bovines, horses, pigs or camels. P75NTR Variants [0054] In a first aspect, the invention relates to isolated polypeptide comprising a p75 neurotrophin receptor (p75NTR) extracellular domain, comprising a variant amino acid at one or more of position 75, 109, 133 and/or 134 within said p75NTR. [0055] As used herein, the term p75NTR protein refers to a p75NTR protein that binds NGF, pro-NGF and/or other neurotrophins (BDNF, NT-3 and/or NT-4/5). As used herein, this means that the p75NTR protein is capable of binding to NGF and inhibiting NGF biological activity and/or downstream pathway(s) mediated by NGF signalling. An NGF binding protein reduces NGF biological activity, including downstream pathways mediated by NGF signalling and/or reduces the amount of NGF that is in circulation, and which can bind to its receptors trkA and NGFR (p75NTR). In certain embodiments the term p75NTR protein refers to a p75NTR protein that binds pro-NGF, i.e., the NGF precursor molecule. As used herein, this means that the p75NTR protein is capable of binding to pro-NGF and inhibiting pro-NGF biological activity and/or downstream pathway(s) mediated by NGF signalling. A pro-NGF binding protein reduces NGF biological activity, including downstream pathways mediated by NGF signalling and/or reduces the amount of NGF that is in circulation, and which can bind to its receptors trkA and NGFR (p75NTR). The p75NTR protein of the present invention may bind pro-NGF and/or NGF. The p75NTR protein of the present invention may demonstrate preferential binding towards NGF or pro-NGF. NGF promotes the survival and differentiation of neurons. NGF is initially synthesized as a precursor, proNGF, which is the predominant form in the central nervous system. NGF and proNGF bind to TrkA/p75NTR to mediate cell survival and to sortilin/p75NTR to promote apoptosis. [0056] The term companion animal as used herein refers to a dog, cat or horse. In one embodiment, the companion animal is a dog. In one embodiment, the companion animal is a cat. In another embodiment, the animal to be treated may be a cow or pig. In another embodiment, the animal to be treated may be a camel. [0057] The term “isolated” molecule, protein or polypeptide refers to a molecule, protein or polypeptide that is substantially free of other proteins or polypeptides, having different antigenic specificities. Moreover, protein or polypeptide may be substantially free of other cellular material and/or chemicals. Thus, the protein, nucleic acids and polypeptides described herein are preferably isolated. Thus, as used herein, an “isolated” protein, or polypeptide means protein or polypeptide that has been identified and separated and/or recovered from a component of its natural cell culture environment. Contaminant components of its natural environment are materials that would interfere with diagnostic or therapeutic uses for the protein or polypeptide, and may include enzymes, hormones, and other proteinaceous or non-proteinaceous solutes. [0058] The terms “polypeptide” and “protein” are used interchangeably to refer to a polymer of amino acid residues and are not limited to a minimum length. Peptides, oligopeptides, dimers, multimers, and the like, are also composed of linearly arranged amino acids linked by peptide bonds, and whether produced biologically, recombinantly, or synthetically and whether composed of naturally occurring or non-naturally occurring amino acids, are included within this definition. Both full-length proteins and fragments thereof are encompassed by the definition. The terms also include co-translational and post-translational modifications of the polypeptide, such as, for example, disulfide-bond formation, glycosylation, acetylation, phosphorylation, proteolytic cleavage (e.g., cleavage by furins or metalloproteases and prohormone convertases (PCs)), and the like. Furthermore, for purposes of the present invention, a “polypeptide” encompasses a protein that includes modifications, such as deletions, additions, substitutions and post-translational modifications (generally conservative in nature as would be known to a person in the art), to the native sequence, as long as the protein maintains the desired activity. These modifications can be deliberate, as through site-directed mutagenesis, or can be accidental, such as through mutations of hosts that produce the proteins, or errors due to PCR amplification or other recombinant DNA methods. Polypeptides or proteins are composed of linearly arranged amino acids linked by peptide bonds, but in contrast to peptides, have a well-defined conformation. [0059] Proteins, as opposed to peptides, generally consist of chains of 50 or more amino acids. For the purposes of the present invention, the term “peptide” as used herein typically refers to a sequence of amino acids of made up of a single chain of D- or L-amino acids or a mixture of D- and L-amino acids joined by peptide bonds. Generally, peptides contain at least two amino acid residues and are less than about 50 amino acids in length. [0060] The present invention relates to molecules comprising a variant of a p75NTR extracellular domain. The variant p75NTR may be, without limitation, a human p75NTR variant, canine p75NTR variant, a feline p75NTR variant, an equine p75TR variant, or a bovine p75NTR variant, or a cameline p75NTR variant. Canine, feline, bovine, equine and cameline p75NTR proteins all have a very high degree of sequence similarity as shown in Figure 1. The variant extracellular domain of p75NTR comprises a different amino acid at one or more position within the polypeptide chain compared to that of the wild-type p75NTR. The variant amino acid may be present at one or more of position 75, 109, 133 and/or 134 of the extracellular domain of p75NTR. Positions 75, 109, 133 and 134 are highlighted in Figure 1. Position numbering is based on the amino acid sequence of the canine, feline, equine, bovine and human p75NTR as set out in SEQ ID No, 1, 3, 5, 36 and 71 respectively. Position numbering is based on the amino acid sequence of the human p75NTR ECD human p75NTR ECD (SEQ ID NO:73), canine p75NTR ECD (SEQ ID NO:7), feline p75NTR ECD (SEQ ID NO:38), equine p75NTR ECD (SEQ ID NO:5), camel p75NTR ECD (SEQ ID NO:101), bovine p75NTR ECD (SEQ ID NO:36), and porcine p75NTR ECD (SEQ ID NO:110), see Figure 1. [0061] The term “variant amino acid” as used herein refers to any amino acid that is not the amino acid present in the wild-type amino acid sequence, in this case the wild-type p75NTR sequence. The wild-type sequence may be a wild-type mammal p75NTR sequence. The wild-type sequence may be a wild-type human p75NTR sequence. The wild-type sequence may be the wild-type canine p75NTR sequence, wild-type feline p75NTR sequence, wild-type equine p75NTR sequence, wild-type bovine p75NTR sequence, or wild-type cameline sequence, which are disclosed herein. The wild-type canine, feline, equine, bovine and human p75NTR sequences are set out in Figure 1 and SEQ ID Nos.1, 3, 5, 36 and 71. When referring to the wild-type p75NTR sequence this may refer to the entire sequence or part thereof, for example the extracellular domain. [0062] The variant amino acid may be a result of substituting, replacing, or modifying the original (e.g., wild-type or germline) amino acid, within a protein sequence, with a different amino acid. The process of substituting or replacing an amino acid can be done using standard techniques available to the skilled person, e.g., using recombinant DNA technology. Modification of an amino acid may be performed post-translationally and a variety of chemical or bioconjuagtion methods may be used to modify said amino acid. The amino acids are changed relative to the native (wild type / germline) sequence as found in nature in the wild type (WT). By “wild type” or “WT” or “native” herein is meant an amino acid sequence or a nucleotide sequence that is found in nature, including allelic variations. A wild-type protein or polypeptide has an amino acid sequence or a nucleotide sequence that has not been intentionally modified. [0063] The term “amino acid” as used herein refers to one of the 20 naturally occurring (canonical) amino acids or any non-natural analogues (non-canonical amino acids) that may be present at a specific, defined position within a peptide sequence. “Amino acid” encompasses both naturally occurring and synthetic amino acids. Although in most cases, when the protein is to be produced recombinantly, only naturally occurring amino acids are used. The variant amino acid may comprise one of the twenty canonical amino acids. The variant amino acid may comprise a non-canonical amino acid, also known are non-natural amino acids for example hydroxyproline, hydroxylysine, phosphoserine, phosphothreonine, phosphotyrosine, N-acetyl lysine, methyllysine. [0064] The variant amino acid at position 75 may be an amino acid selected from alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine. The variant amino acid at position 109 may be selected from alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, threonine, tryptophan, tyrosine, valine. The variant amino acid at position 133 may be selected from alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine. The variant amino acid at position 134 may be selected from alanine, arginine, asparagine, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine. [0065] The variant amino acid at position 75 may be an amino acid comprising a polar side chain. For example, the variant amino acid at position 75 may be selected from serine, threonine, tyrosine, tryptophan, asparagine, glutamine or cysteine. Preferably the variant amino acid at position 75 comprises a small polar side chain for example serine or threonine. In one embodiment the variant amino acid at position 75 is threonine. [0066] The variant amino acid at position 109 may be an amino acid comprising an aromatic side chain. For example, the variant amino acid at position 109 may be selected from histidine, tyrosine, phenylalanine, or tryptophan. In one embodiment the variant amino acid at position 109 is histidine. In one embodiment the variant amino acid at position 109 is tyrosine. [0067] The variant amino acid at position 133 may be an amino acid comprising a charged side chain. For example, the variant amino acid at position 133 may be selected from arginine, histidine, lysine, aspartic acid, or glutamic acid. In one embodiment the variant amino acid at position 133 may be an amino acid comprising a negatively charged side chain. For example, the variant amino acid at position 133 is selected from arginine, histidine, or lysine. In one embodiment the variant amino acid at position 133 is arginine. [0068] The variant amino acid at position 134 may be an amino acid comprising a hydrophobic side chain. For example, the variant amino acid at position 134 may be selected from alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine, or tryptophan. In one embodiment the variant amino acid a position 134 may be an amino acid comprising a non- aromatic hydrophobic side chain. For example, the variant amino acid at position 134 is selected from alanine, valine, isoleucine, leucine, or methionine. In one embodiment the variant amino acid at position 134 is leucine or isoleucine. In one embodiment the variant amino acid is leucine. [0069] Amino acid modifications in general refer to and include substitutions, insertions and deletions, with the former being preferred in many cases. The variant extracellular domain of p75NTR of the invention described herein, comprising a variant amino acid at one or more of positions 75, 109, 133 and/or 134, may comprise additional variant amino acids within the polypeptide sequence. These additional variant amino acids can include any number of further modifications, as long as the function of the protein is still present, as described herein. It will be clear to the skilled person that additional mutations may occur naturally within the amino acid sequence or additional mutations may be genetically engineered for example to increase stability or reduce glycosylation. In one embodiment, from 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 modifications are generally utilized as often the goal is to alter function with a minimal number of modifications. A variant polypeptide sequence will preferably possess at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to the wild-type sequences or the parent sequences. It should be noted that depending on the size of the sequence, the percent identity will depend on the number of amino acids. [0070] By “protein variant” or “variant protein” herein is meant a protein that differs from a wild-type protein by virtue of at least one amino acid modification. The isolated polypeptide according to the invention comprises a p75 neurotrophin receptor (p75NTR) extracellular domain, comprising a variant amino acid at one or more of position 75, 109, 133 and/or 134 within said p75NTR, however the skilled person would understand that further variant amino acids may be present within said p75NTR compared to the wild-type p75NTR. The positions referred to herein are with respect the to the p75NTR extracellular domain. The parent polypeptide may be a naturally occurring or wild-type (WT) polypeptide, or may be a modified version of a WT polypeptide. Variant polypeptide may refer to the polypeptide itself, a composition comprising the polypeptide, or the amino sequence that encodes it. Preferably, the variant polypeptide has at least one amino acid modification compared to the parent polypeptide, e.g., from about one to about ten amino acid modifications, and preferably from about one to about five amino acid modifications compared to the parent. The variant polypeptide sequence herein will preferably possess at least about 80% identity with a parent polypeptide sequence, and most preferably at least about 90% identity, more preferably at least about 95% identity. Variants do not include human sequences. [0071] By “parent polypeptide”, “parent protein” as used herein is meant an unmodified polypeptide that is subsequently modified to generate a variant. Said parent polypeptide may be a naturally occurring polypeptide, or a variant or engineered version of a naturally occurring polypeptide. Parent polypeptide may refer to the polypeptide itself, compositions that comprise the parent polypeptide, or the amino acid sequence that encodes it. [0072] The p75 neurotrophin receptor p75NTR in its native form exists as a transmembrane glycoprotein. Family members are characterised by multiple cysteine-rich domains for ligand binding, a single transmembrane sequence extracellular domain (ECD), and a non-catalytic cytoplasmic domain. As used herein, a portion of p75NTR or a portion of the ECD of p75NTR includes at least one neurotrophin binding domain. [0073] Endogenous soluble ECD of p75NTR is produced by regulated proteolysis by α-secretase and γ-secretase that cleaves the protein near the membrane junction of the ECD. This cleavage results in the release of the cytoplasmic domain which is free to bind NGF as a natural antagonist to NGF signalling. [0074] In one embodiment, the extracellular domain of p75NTR according to the invention comprises the full-length extracellular domain (ECD) or part thereof. A part of the ECD of p75NTR may comprise various truncations of the full-length ECD. Truncations of the ECD of p75NTR may be produced using techniques known in the art such as recombinant DNA techniques. In one embodiment, the extracellular domain of p75NTR comprises or consists of the full-length ECD. In one embodiment, the extracellular domain of p75NTR comprises the extracellular domain (ECD) and additional C-terminal amino acids of the p75NTR protein adjacent to the ECD. For example, the portion of the p75NTR protein may comprise the ECD and at least 1- 5 or 5-10 amino acids, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 C-terminal amino acids of the p75NTR protein adjacent to the ECD; or the ECD and at least 10-20 amino acids, or the ECD and at least 20-30 amino acids, or the ECD and at least 30-40 amino acids, or the ECD and at least 40-50 amino acids, or the ECD and at least 50-60 amino acids, or the ECD and at least 60-70 amino acids, or the ECD and at least 70-80 amino acids, or the ECD and at least 80-90 amino acids, or the ECD and at least 90-100 amino acids, or the ECD and at least 100-110 amino acids, or the ECD and at least 110-120 amino acids, or the ECD and at least 120-130 amino acids, or the ECD and at least 130-140 amino acids, or the ECD and at least 140-150 amino acids, or the ECD and at least 150-160 amino acids, or the ECD and at least 160-170 amino acids or the ECD and at least 170-180 amino acids C-terminal amino acids of the companion animal p75NTR protein adjacent to the ECD. [0075] In one embodiment, α-secretase and γ-secretase cleavage sites within the ECD are removed. In one embodiment, all or a part of the stalk region is removed. As used herein, the stalk region refers to the amino acids downstream from the conserved EEIP sequence at positions 161-164. In one embodiment, the stalk region and α-secretase and γ-secretase cleavage sites within the ECD are removed. In one embodiment, a portion of the N-terminus of the mature p75NTR protein is removed, e.g., 1 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more amino acids at the N- terminus. In one embodiment, a portion of the amino acids directly upstream of the stalk region are removed, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more contiguous amino acids. [0076] In one embodiment, the p75NTR extracellular domain is canine and comprises or consists of SEQ ID NO:7 or a variant thereof or a portion thereof. Variants according to the invention comprise a variant amino acid at one or more of positions 75, 109, 133 and/or 134, for example SEQ ID NO:46, SEQ ID NO:49, SEQ ID NO:52, SEQ ID NO:55 or SEQ ID NO:58. In an embodiment the isolated polypeptide comprising a companion animal p75 neurotrophin receptor (p75NTR) extracellular domain, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134 comprises or consists of SEQ ID NO:46, SEQ ID NO:49, SEQ ID NO:52, SEQ ID NO:55 or SEQ ID NO:58. [0077] In another embodiment, the isolated companion animal p75NTR extracellular domain is feline and comprises or consists of SEQ ID NO:38 or a variant thereof or a portion thereof. Variants according to the invention comprise a variant amino acid at one or more of positions 75, 109, 133 and/or 134 for example SEQ ID NO:61, SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67 or SEQ ID NO:69. In an embodiment the isolated polypeptide comprising a companion animal p75 neurotrophin receptor (p75NTR) extracellular domain, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134 comprises or consists of SEQ ID NO:61, SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67 or SEQ ID NO:69. [0078] In another embodiment, the isolated p75NTR extracellular domain is human and comprises or consists of SEQ ID NO:71 or a variant thereof or a portion thereof. Variants according to the invention comprise a variant amino acid at one or more of positions 75, 109, 133 and/or 134 for example SEQ ID NO:84, SEQ ID NO:87, SEQ ID NO:90, SEQ ID NO:93 or SEQ ID NO:96. In an embodiment the isolated polypeptide comprising a human p75 neurotrophin receptor (p75NTR) extracellular domain, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134 comprises or consists of SEQ ID NO:84, SEQ ID NO:87, SEQ ID NO:90, SEQ ID NO:93 or SEQ ID NO:96. [0079] In another embodiment, the isolated p75NTR extracellular domain is bovine and comprises or consists of SEQ ID NO: 36. or a variant thereof or a portion thereof. Variants according to the invention comprise a variant amino acid at one or more of positions 75, 109, 133 and/or 134 for example SEQ ID NO:127, SEQ ID NO:128, SEQ ID NO:129, SEQ ID NO:130, SEQ ID NO:131. [0080] In another embodiment, the isolated p75NTR extracellular domain is camelid and comprises or consists of SEQ ID NO: 99 or a variant thereof or a portion thereof. Variants according to the invention comprise a variant amino acid at one or more of positions 75, 109, 133 and/or 134 for example SEQ ID NO:103, SEQ ID NO:104, SEQ ID NO:105, SEQ ID NO:106, SEQ ID NO:107. [0081] In another embodiment, the isolated p75NTR extracellular domain is porcine and comprises or consists of SEQ ID NO: 108 or a variant thereof or a portion thereof. Variants according to the invention comprise a variant amino acid at one or more of positions 75, 109, 133 and/or 134 for example SEQ ID NO: 112, SEQ ID NO:113, SEQ ID NO:114, SEQ ID NO:115, SEQ ID NO: 116. [0082] In another embodiment, the isolated p75NTR extracellular domain is equine and comprises or consists of SEQ ID NO: 5 or a variant thereof or a portion thereof. Variants according to the invention comprise a variant amino acid at one or more of positions 75, 109, 133 and/or 134 for example SEQ ID NO:120, SEQ ID NO:121, SEQ ID NO:122, SEQ ID NO:123, SEQ ID NO:124. [0083] The ECD of p75NTR has a stalk region (e.g., SEQ ID NO:9, canine stalk region) that is prone to O-glycosylation. Glycosylation in proteins can cause manufacturing difficulties. Thus, in one embodiment, the isolated ECD may comprise deletions in the stalk region to reduce the number of O-glycosylation sites within the stalk region e.g., to form a truncated stalk region. A truncated stalk region may comprise any number of the amino acids of the stalk region. For example, the stalk region may comprise 1-10, 1-20, 1-30 amino acids. The stalk region may be removed in embodiments described herein. Point mutations may be introduced into the stalk region to produce a stalk region with a reduced number of o-glycosylation sites. For example, point mutations may be used to introduced variant amino acids at the o-glycosylation sites to prevent glycosylation occurring at these sites. Thus, a portion of the ECD as used herein may be the ECD without the stalk region and 3’ sequences α-secretase and γ-secretase cleavage sites (e.g., SEQ ID NO:34). [0084] Thus, in one embodiment, the ECD of the p75NTR is a truncated protein which has the O-glycosylation stalk region removed. [0085] The p75NTR molecules described herein are capable of binding pro-NGF and/or NGF. Pro-NGF and NGF have different activities in-vivo, with pro-NGF showing pro- inflammatory, catabolic and apoptotic effects and NGF having anti-inflammatory, anabolic and proliferative effects. In an embodiment the isolated polypeptide comprising a p75NTR ECD wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134, is capable of binding to NGF and inhibiting NGF biological activity and/or downstream pathway(s) mediated by NGF signalling. The isolated polypeptide comprising a p75NTR ECD may also be capable of binding to pro-NGF and inhibiting pro-NGF biological activity and/or downstream pathway(s) mediated by pro-NGF signalling. The isolated polypeptide comprising a p75NTR ECD may preferentially bind and inhibit NGF over pro-NGF. The isolated polypeptide comprising a p75NTR ECD may preferentially bind and inhibit pro-NGF over NGF. In certain embodiments for example where an anti-inflammatory effect is desirable, it may be advantageous to have a p75NTR molecule that preferentially binds pro-NGF over NGF. [0086] The isolated polypeptide comprising a p75NTR ECD wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134, has an altered binding affinity for its target compared to the wild-type p75NTR ECD. The p75NTR ECD of the invention may have an altered binding affinity for one or more or NGF, pro-NGF BDNF, NT3, NT4 compared to the wild-type p75NTR ECD. In an embodiment the binding affinity of the variant p75NTR ECD of the invention is increased for one or more or NGF, pro-NGF, BDNF, NT3, NT4 compared to the wild-type p75NTR ECD. In an embodiment the binding affinity of the variant p75NTR ECD of the invention is decreased for one or more or NGF, pro-NGF, BDNF, NT3, NT4 compared to the wild-type p75NTR ECD. [0087] In an embodiment isolated polypeptide comprising a p75NTR ECD, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134 comprises an altered binding affinity for NGF compared to the wild-type p75NTR ECD. In an embodiment the p75NTR ECD of the invention comprises an altered binding affinity for NGF compared to the wild-type p75NTR ECD but retains a similar binding affinity for BDNF, NT3 and/or NT4. In an embodiment the binding affinity of the variant p75NTR ECD is increased for NGF compared to the wild-type p75NTR ECD. In an embodiment the binding affinity of the variant p75NTR ECD of the invention is decreased for NGF compared to the wild-type p75NTR ECD. In an embodiment isolated polypeptide comprising a p75NTR ECD, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134 comprises an altered binding affinity for pro-NGF compared to the wild-type p75NTR ECD. In an embodiment the p75NTR ECD of the invention comprises an altered binding affinity for pro-NGF compared to the wild-type p75NTR ECD but retains a similar binding affinity for BDNF, NT3 and/or NT4. In an embodiment the binding affinity of the variant p75NTR ECD is increased for pro-NGF compared to the wild-type p75NTR ECD. In an embodiment the binding affinity of the variant p75NTR ECD of the invention is decreased for pro-NGF compared to the wild-type p75NTR ECD Nucleic Acids [0088] In another aspect, the invention relates to an isolated nucleic acid encoding the isolated polypeptide comprising a p75 neurotrophin receptor (p75NTR) extracellular domain, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134 within said p75NTR. [0089] In one embodiment, the p75NTR is from a human and the isolated nucleic acid encodes SEQ ID NO:84, SEQ ID NO:87, SEQ ID NO:90, SEQ ID NO:93 or SEQ ID NO:96. In one embodiment, the companion animal is a dog and the isolated nucleic acid encodes SEQ ID NO:46, SEQ ID NO:49, SEQ ID NO:52, SEQ ID NO:55 or SEQ ID NO:58. In one embodiment the companion animal is a cat and the isolated nucleic acid encodes SEQ ID NO:61, SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67 or SEQ ID NO:69. [0090] “Isolated nucleic acid molecule” means a DNA or RNA of genomic, mRNA, cDNA, or synthetic origin or some combination thereof which is not associated with all or a portion of a polynucleotide in which the isolated polynucleotide is found in nature or is linked to a polynucleotide to which it is not linked in nature. [0091] In another aspect, the invention relates to a vector, plasmid, transcription, expression cassette or nucleic acid construct comprising a nucleic acid encoding the ECD of a p75NTR, e.g., the ECD or portion thereof as described above. [0092] The construct may include a suitable leader sequence. The term leader sequence is used interchangeably with signal sequence. Thus, in some embodiments, the nucleic acid sequence / nucleic acid construct encoding the fusion protein may also comprise a leader sequence. The leader sequence is made as part of the protein and then cleaved off when the protein is secreted. Any suitable leader sequence may be used, including a native immunoglobulin germline leader sequence, such as the endogenous p75 leader of the relevant species (e.g. human, canine, equine, feline, bovine, cameline), the endogenous p75 leader of a different species e.g. a mouse IgG leader or another leader sequences known in the art, e.g. the Campath leader sequence (see US 8,362,208 B2) or an artificial sequence. Such leader sequences can aid in enhancing protein expression. [0093] In another aspect, the invention relates to a host cell comprising a nucleic acid encoding an ECD of a human, companion animal, or other p75NTR, e.g., the ECD, or a vector, plasmid, vector, transcription, expression cassette or construct as described above. [0094] Expression vectors of use in the invention may be constructed from a starting vector such as a commercially available vector. After the vector has been constructed and the nucleic acid molecule has been inserted into the proper site of the vector, the completed vector may be inserted into a suitable host cell for amplification and/or polypeptide expression. [0095] The term “vector” means a construct, which is capable of delivering, and in some aspects expressing one or more gene(s) or sequence(s) of interest in a host cell. Examples of vectors include, but are not limited to, viral vectors, naked DNA or RNA expression vectors, plasmid, cosmid or phage vectors, DNA or RNA expression vectors associated with cationic condensing agents, DNA or RNA expression vectors encapsulated in liposomes, and certain eukaryotic cells, such as producer cells. [0096] The invention also relates to an isolated recombinant host cell comprising one or more nucleic acid molecule plasmid, vector, transcription or expression cassette as described above. The transformation of an expression vector into a selected host cell may be accomplished by well-known methods including transfection, infection, calcium phosphate co- precipitation, electroporation, microinjection, lipofection, DEAE-dextran mediated transfection, or other known techniques. The method selected will in part be a function of the type of host cell to be used. [0097] The host cell may be eukaryotic or prokaryotic, for example a bacterial, viral, plant, fungal, mammalian or other suitable host cell. In one embodiment, the cell is an E. coli cell. In another embodiment, the cell is a yeast cell. In another embodiment, the cell is a Chinese Hamster Ovary (CHO) cell, HeLa cell or other cell that would be apparent to the skilled person. Mammalian cell lines available as hosts for expression are well known in the art and include, but are not limited to, immortalized cell lines available from the American Type Culture Collection (ATCC) and any cell lines used in an expression system known in the art can be used to make the recombinant polypeptides of the invention. [0098] In general, host cells are transformed with a recombinant expression vector that comprises DNA encoding a protein. Among the host cells that may be employed are prokaryotes, yeast or higher eukaryotic cells. Prokaryotes include gram negative or gram-positive organisms, for example E. coli or bacilli. Higher eukaryotic cells include insect cells and established cell lines of mammalian origin. Examples of suitable mammalian host cell lines include the COS-7 cells, L cells, CI27 cells, 3T3 cells, Chinese hamster ovary (CHO) cells, or their derivatives and related cell lines which grow in serum free media, HeLa cells, BHK cell lines, the CVIIEBNA cell line, human embryonic kidney cells such as 293, 293 EBNA or MSR 293, human epidermal A431 cells, human Colo205 cells, other transformed primate cell lines, normal diploid cells, cell strains derived from in vitro culture of primary tissue, primary explants, HL-60, U937, HaK or Jurkat cells. Optionally, mammalian cell lines such as HepG2/3B, KB, NIH 3T3 or S49, for example, can be used for expression of the polypeptide when it is desirable to use the polypeptide in various signal transduction or reporter assays. [0099] Other suitable host cells include insect cells, using expression systems such as baculovirus in insect cells, plant cells, transgenic plants and transgenic animals, and by viral and nucleic acid vectors. [0100] Alternatively, it is possible to produce the polypeptide in lower eukaryotes such as fungal cell lines and yeast or in prokaryotes such as bacteria. Suitable yeasts include S. cerevisiae, S. pombe, Kluyveromyces strains, Pichia pastoris, Candida, or any yeast strain capable of expressing heterologous polypeptides. Suitable bacterial strains include E. coli, B. subtilis, S. typhimurium, or any bacterial strain capable of expressing heterologous polypeptides. If the protein is made in yeast or bacteria, it may be desirable to modify the product produced therein, for example by phosphorylation or glycosylation of the appropriate sites, in order to obtain a functional product. Such covalent attachments can be accomplished using known chemical or enzymatic methods. [0101] A host cell, when cultured under appropriate conditions, can be used to express a protein that can subsequently be collected from the culture medium (if the host cell secretes it into the medium) or directly from the host cell producing it (if it is not secreted). The selection of an appropriate host cell will depend upon various factors, such as desired expression levels, polypeptide modifications that are desirable or necessary for activity (such as glycosylation or phosphorylation) and ease of folding into a biologically active molecule. [0102] In another aspect, the invention also relates to the use of an isolated p75NTR protein or a portion thereof as described above in a fusion protein with another moiety, e.g. with a half-life extending moiety as described in more detail below. Therefore, the p75NTR protein or a portion thereof can be provided covalently linked or couple to a half-life extending moiety. Alternatively, it may be provided incorporated in a liposome. The invention further relates to an isolated p75NTR protein or a portion thereof for use in therapy. Further, there is provided an isolated p75NTR protein or a portion thereof for use in the treatment of a pain related disease. Such diseases are described in more detail below. [0103] In some embodiments, to improve its pharmacokinetic (PK) properties, the half-life of the p75NTR protein is extended. Fusion Proteins [0104] Thus, in another aspect, the invention relates to a fusion protein comprising a p75 neurotrophin receptor (p75NTR) extracellular domain, comprising a variant amino acid at one or more of position 75, 109, 133 and/or 134 within said p75NTR, and another moiety. The fusion protein may comprise an extracellular domain of a p75 neurotrophin receptor (p75NTR), wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134, and another moiety. [0105] For example, the other moiety may be a half-life extending moiety. Thus, the p75NTR protein or portion thereof (e.g., extracellular domain) is coupled to a half-life extending moiety. As described above, the p75NTR protein or portion thereof may be human, canine, feline, bovine, equine, or cameline. The p75NTR protein or portion thereof used in the fusion protein may thus comprise or consist of a sequence selected from SEQ ID NO:1, 3, 5, 7, 34, 36, 38, 71, or 73 or a portion or a variant thereof, in particular the variant may comprise a variant amino acid at one or more of position 75, 109, 133 and/or 134. In certain embodiments, all or part of the stalk region of the p75NTR is removed. In certain embodiments of the canine p75NTR protein or portion, the stalk region (e.g., SEQ ID NO:9) is removed. In certain embodiments of the feline p75NTR protein or portion, the stalk region is removed. In certain embodiments of the human p75NTR protein or portion, the stalk region (e.g., SEQ ID NO:25) is removed. [0106] Half-life extending moieties have been described. For example, the half-life extending moiety may be selected from the following non-limiting list: a human immunoglobulin Fc domain, a companion animal immunoglobulin Fc domain, polyethylene glycol (PEG), PEG derivatives, simple lipids, lipid dicarboxylic acids, lipids with additional moieties, human or companion animal serum albumin binders, e.g. small-molecule binders or antibodies/antibody fragments that bind human or companion animal serum albumin, companion animal serum albumin, or streptococcal protein G’s albumin-binding domain (ABD). Examples of lipids include glucagon-like peptide 1 (GLP-1), the analogs GLP-1 liraglutide and semaglutide or cholesterol. Advantageously, using an immunoglobulin Fc domain facilitates purification of the protein. In particular, Fc binding to Protein A can be used in purification procedures. The presence of an immunoglobulin Fc domain can also stabilise the overall folding of the fusion protein as well as extending its half-life. [0107] In certain embodiments, where the half-life extending moiety is an Fc domain, serum albumin binder, or serum albumin, the extracellular domain of p75NTR and half- life extending moiety are from / specific to the same species. For example, in one embodiment, the half-life extending moiety is a companion animal Fc domain of the corresponding companion animal. For example, if the extracellular domain of p75NTR is canine, the Fc domain is canine. If the extracellular domain of p75NTR is feline, the Fc domain is feline. If the extracellular domain of p75NTR is equine, the Fc domain is equine. If the extracellular domain of p75NTR is bovine, the Fc domain is bovine. [0108] In one embodiment, where the half-life extending moiety is an Fc domain, human serum albumin binder or human serum albumin, the extracellular domain of p75NTR and half-life extending moiety are both derived from human. [0109] The human serum albumin binder, e.g., antibody of fragment thereof, may be fully human or humanized. The human serum albumin binder binds to human serum albumin. [0110] However, given the high sequence similarity between p75 proteins, in certain embodiments, where the half-life extending moiety is a companion animal Fc domain, companion animal serum albumin binder or companion animal serum albumin, the p75NTR protein or portion and half-life extending moiety are not from / specific to the same companion animal. For example, in one embodiment, the half-life extending moiety is the companion animal Fc domain of the corresponding companion animal, but the p75 protein or portion thereof is that of a different companion animal. For example, for treatment of dogs, if the Fc domain is canine, the p75NTR protein or portion thereof, e.g., the extracellular domain is may be from a different animal, e.g. cat, cow, horse, pig, or camel. For example, for treatment of cats, if the Fc domain is feline, the p75NTR protein or portion thereof, e.g., the extracellular domain is may be from a different animal, e.g. dog, cow, pig, horse, or camel. For example, for treatment of cats, if the Fc domain is equine, the p75NTR protein or portion thereof, e.g., the extracellular domain is may be from a different animal, e.g. cat, cow, dog, pig, or camel. In yet another embodiment, human p75 or a portion thereof fused to companion animal Fc can be used. [0111] The companion animal serum albumin binder, e.g., antibody or fragment thereof, may be canine or caninized, feline or felinized, equine or equinized, bovine or bovinized, camel or camelized, pig or porcinized. The companion animal serum albumin binder may bind to canine, feline, bovine, equine, or cameline serum albumin. [0112] In one embodiment, the half-life extending moiety is a wild type or variant Fc domain. The term variant is as defined above. For example, an Fc domain variant may have modified half-life compared to the wild-type Fc domain. In one embodiment, the Fc domain is a Fc domain, that is a wild-type domain or a variant thereof. Variant Fc domains are described, for example in WO2020/142625. [0113] By “Fc” or “Fc region” or “Fc domain” as used herein is meant the polypeptide comprising the constant region of an antibody excluding the first constant region immunoglobulin domain (CH1) and, in some cases, part of the hinge. In one embodiment, the Fc domain includes constant region immunoglobulin domains CH2, CH3 and the hinge region between CH1 and CH2 or part of the hinge region. [0114] Proteolytic digestion of antibodies releases different fragments termed Fv (Fragment variable), Fab (Fragment antigen binding) and Fc (Fragment crystallisation). The Fc fragment comprises the carboxy-terminal portions of both H chains held together by disulfides. The constant domains of the Fc fragment are responsible for mediating the effector functions of an antibody. [0115] In canine, there are four IgG heavy chains referred to as A, B, C, and D. These heavy chains represent four different subclasses of dog IgG, which are referred to as IgG- A, IgG-B, IgG-C and IgG-D. The DNA and amino acid sequences of these four heavy chains were first identified by Tang et al. (Vet. Immunol. Immunopathol. 80: 259-270 (2001)). Exemplary amino acid and DNA sequences for these heavy chains are also available from the GenBank data bases (IgGA: accession number AAL35301.1, IgGB: accession number AAL35302.1, IgGC: accession number AAL35303.1, IgGD: accession number AAL35304.1). Amino acid sequences for IgG-A, IgG-B, IgG-C and IgG-D as used by the inventors and according to the aspects and embodiments of the invention are provided as SEQ ID Nos.15, 16, 17, 18). [0116] In human, Fc refers to the last two constant region immunoglobulin domains of IgA, IgD, and IgG, the last three constant region immunoglobulin domains of IgE and IgM, and the flexible hinge N-terminal to these domains. For IgA and IgM, Fc may include the J chain. For IgG, the Fc domain comprises immunoglobulin domains CH2 and CH3 and the lower hinge region between CH1 and CH2. Although the boundaries of the Fc region may vary, the human IgG heavy chain Fc region is usually defined to include residues C226 or P230 to its carboxyl- terminus, wherein the numbering is according to the EU index as in Kabat. [0117] Fc as used herein may refer to the Fc region in isolation, or this region in the context of an Fc fusion (“fusion composition” or “fusion construct”), as described herein. Fc domains include all or part of an Fc region; that is, N- or C- terminal sequences may be removed from wild-type or variant Fc domains, as long as this does not affect function. [0118] Briefly, IgG functions are generally achieved via interaction between the Fc region of the Ig and an Fcγ receptor (FcγR) or another binding molecule, sometimes on an effector cell. This can trigger the effector cells to kill target cells to which the antibodies are bound through their variable (V) regions. Also, antibodies directed against soluble antigens might form immune complexes which are targeted to FcγRs which result in the uptake (opsonisation) of the immune complexes or in the triggering of the effector cells and the release of cytokines. [0119] By “Fc gamma receptor”, “ FcγR “ or “FcgammaR” as used herein is meant any member of the family of proteins that bind the IgG antibody Fc region and is encoded by an FcγR gene. [0120] In humans, three classes of FcγR have been characterised, although the situation is further complicated by the occurrence of multiple receptor forms. The three classes are: [0121] (i) FcγRI (CD64) including isoforms FcγRIa, FcγRIb, and FcγRIc binds monomeric IgG with high affinity and is expressed on macrophages, monocytes, and sometimes neutrophils and eosinophils; [0122] (ii) FcγRII (CD32) binds complexed IgG with medium to low affinity and is widely expressed. These receptors can be divided into two important types, FcγRIIa and FcγRIIb. The ‘a’ form of the receptor is found on many cells involved in killing (e. g. macrophages, monocytes, neutrophils) and seems able to activate the killing process and occurs as two alternative alleles. The ‘b’ form seems to play a role in inhibitory processes and is found on B-cells, macrophages and on mast cells and eosinophils. On B-cells it seems to function to suppress further immunoglobulin production and isotype switching to for example, the IgE class. On macrophages, the b form acts to inhibit phagocytosis as mediated through FcγRIIa. On eosinophils and mast cells the b form may help to suppress activation of these cells through IgE binding to its separate receptor and [0123] (iii) FcyRIII (CD16) binds IgG with medium to low affinity and exists as two types. FcγRIIIa is found on NK cells, macrophages, eosinophils and some monocytes and T cells and mediates ADCC. [0124] FcγRIIIb is highly expressed on neutrophils. Both types have different allotypic forms. [0125] Canine Fc receptors are described in Bergeron et al L.M. Bergeron et al.; Veterinary Immunology and Immunopathology 157 (2014) 31– 41. Canine has RI, RIIb, RIII, but not Riia. [0126] As well as binding to FcγRs, IgG antibodies can activate complement and this can also result in cell lysis, opsonisation or cytokine release and inflammation. The Fc region also mediates such properties as the transportation of IgGs to the neonate (via the so-called “FcRn”), increased half-life (also believed to be effected via an FcRn-type receptor) and self- aggregation. The Fc-region is also responsible for the interaction with protein A and protein G (which interaction appears to be analogous to the binding of FcRn). [0127] By “effector function” as used herein is meant a biochemical event that results from the interaction of an antibody Fc region with an Fc receptor or ligand. Effector functions include but are not limited to antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cell-mediated phagocytosis (ADCP) and complement-dependent cytotoxicity (CDC). [0128] In one embodiment, the ECD of p75NTR, and the other moiety are linked with a linker moiety or otherwise conjugated, attached or covalently or non-covalently linked. Suitable linkers are known to the skilled person. For example, the linker is a peptide linker, such as a glycine and/or alanine and/or threonine and/or serine-rich linker e.g. a glycine-serine linker, such as (G4S)n wherein n is 1 to 4. [0129] In another embodiment, the linker can be cleavable. The linker may be an acid labile linker, a proteolytically cleavable linker, an enzymatically cleavable linker, an oxidation sensitive linker. [0130] In one embodiment of the fusion protein, the companion animal p75NTR protein or portion thereof comprises or consists of a variant canine p75NTR ECD or portion thereof. In one embodiment, the ECD is canine and comprises of consists of a sequence selected from SEQ ID NO:46, SEQ ID NO:49, SEQ ID NO:52, SEQ ID NO:55 or SEQ ID NO:58. In one embodiment the ECD is feline and comprises or consists of a sequence selected from SEQ ID NO:61, SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67 or SEQ ID NO:69. In one embodiment the ECD is human and comprises or consists of a sequence selected from SEQ ID NO:84, SEQ ID NO:87, SEQ ID NO:90, SEQ ID NO:93 or SEQ ID NO:96. [0131] Thus, in one embodiment, the invention relates to a fusion protein comprising a canine p75NTR ECD linked to a canine Fc domain. In one embodiment, the ECD comprises of consists of a sequence selected from SEQ ID NO:46, SEQ ID NO:49, SEQ ID NO:52, SEQ ID NO:55 or SEQ ID NO:58 or a variant thereof operably linked to a canine Fc domain. In one embodiment, the invention relates to a fusion protein comprising a feline p75NTR ECD linked to a feline Fc domain. In one embodiment, the ECD comprises of consists of a sequence selected from SEQ ID NO:61, SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67 or SEQ ID NO:69 or a variant thereof operably linked to a feline Fc domain. In one embodiment, the invention relates to a fusion protein comprising a human p75NTR ECD linked to a human Fc domain. In one embodiment, the ECD comprises of consists of a sequence selected from SEQ ID NO:84, SEQ ID NO:87, SEQ ID NO:90, SEQ ID NO:93 or SEQ ID NO:96 or a variant thereof operably linked to a human Fc domain. [0132] In one embodiment, the fusion protein of the present invention preferably binds to any one or more of NGF, BDNF, NT3 or NT4/5 with a binding affinity (Kd) of between about lpM to about 100 nM. In some preferred embodiments, the binding affinity (Kd) is between about 5pM and any of about 10 pM, 20pM, 40pM, 50pM 100ρΜ, 0.2nM, 0.5nM, lnM 1.5nM 2 nM, 2.5 nM, 3 nM, 3.5 nM, 4 nM, 4.5 nM, 5 nM, 5.5 nM, 6 nM, 6.5 nM, 7 nM, 7.5 nM, 8 nM, 8.5 nM, 9 nM, 9.5 nM, 10 nM, 15 nM, 20 nM, 25 nM, 30 nM, 35 nM, 40 nM, 45 nM, 50 nM or 100 nM as measured in an in vitro binding assay for NGF, pro-NGF, BDNF, NT3 or NT4/5 such as described herein. Subnanomolar range is preferred. [0133] In one embodiment, the fusion protein comprises SEQ ID NO:46, SEQ ID NO:49, SEQ ID NO:52, SEQ ID NO:55 or SEQ ID NO:58 or a variant thereof. Fusion proteins according to the invention may include a variant p75NTR ECD with a variant amino acid at one or more of position 75, 109, 133 and/or 134, operably linked to a canine Fc domain. The Fc domain in the fusion protein construct may be a wild-type canine Fc domain such as SEQ ID NO:20. The Fc domain in the fusion protein construct may be a variant canine Fc domain which has been modified to increase half-life for example SEQ ID NO:21. In this domain, the mutation YTE has been introduced at residues Y252 – T254 of the wild-type Fc domain using EU numbering. The fusion protein may be generated by combining a variant p75NTR ECD such as SEQ ID NO:46, SEQ ID NO:49, SEQ ID NO:52, SEQ ID NO:55 or SEQ ID NO:58 with a canine Fc domain such as SEQ ID NO:20 or 21. The fusion protein may comprise or consist of a sequence selected from SEQ ID NO:47, SEQ ID NO:50, SEQ ID NO:53, SEQ ID NO:56 or SEQ ID NO:59. [0134] In an embodiment the fusion protein comprises a wild-type feline p75NTR ECD operably linked to a feline Fc. In an embodiment, the fusion protein comprises or consists of SEQ ID NO:39, such a fusion protein includes the wild-type feline p75 ECD operably linked to a feline Fc domain. The Fc domain in the construct of SEQ ID NO:39 is a wild type feline IgG2 Fc domain. In an embodiment, the fusion protein comprises or consists of SEQ ID NO:42, such a fusion protein includes the feline p75 ECD operably linked to a feline Fc domain. The Fc domain in the construct of SEQ ID NO:42 is a wild type feline IgG1 Fc domain. In another embodiment, the fusion protein comprises or consists of SEQ ID NO:44, such a fusion protein includes the feline p75 ECD operably linked to a feline Fc domain. The Fc domain in the construct of SEQ ID NO:44 is a wild type feline IgG3 Fc domain. [0135] In one embodiment, the fusion protein comprises SEQ ID NO:61, SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67 or SEQ ID NO:69 or a variant thereof. Fusion proteins according to the invention may include a variant feline p75NTR ECD with a variant amino acid at one or more of position 75, 109, 133 and/or 134, operably linked to a feline Fc domain. The Fc domain in the fusion protein construct may be a wild type feline Fc domain such as SEQ ID NO:24, 25, 26 or 41. For example the fusion protein may be generated by combining a variant p75NTR ECD such as SEQ ID NO:61, SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67 or SEQ ID NO:69 with a feline Fc domain such as SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26 or SEQ ID NO:41. The Fc domain in the fusion protein construct may be a variant feline Fc domain which has been modified to increase half-life, the skilled person would be able to determine suitable half- life extending variants. The fusion protein may comprise or consist of a sequence selected from SEQ ID NO:62, SEQ ID NO:64, SEQ ID NO:66, SEQ ID NO:68 or SEQ ID NO:70. [0136] Modified companion animal Fc domains that include a half-life extending mutation or mutations, e.g., canine, feline or equine Fc domains, can be used in the fusion proteins of the invention. A skilled person would know that any other known mutations that increase half- life could also be introduced in the Fc domain. [0137] In one embodiment, the fusion protein comprises or consists of SEQ ID NO:85, SEQ ID NO:88, SEQ ID NO:91, SEQ ID NO:94 or SEQ ID NO:97 or a variant thereof. Fusion proteins according to the invention may include a variant p75NTR ECD with a variant amino acid at one or more of position 75, 109, 133 and/or 134, operably linked to a human Fc domain. The Fc domain in the fusion protein construct may be a wild-type human Fc domain such as SEQ ID NO:77, SEQ ID NO:78, SEQ ID NO:79, or SEQ ID NO:80. The Fc domain in the fusion protein construct may be a variant human Fc domain which has been modified to increase half-life. Suitable modifications to increase the half-life of a human Fc domain are known in the art. The fusion protein may be generated by combining a variant p75NTR ECD such as SEQ ID NO:84, SEQ ID NO:87, SEQ ID NO:90, SEQ ID NO:93 or SEQ ID NO:96 with a human Fc domain such as SEQ ID NO:77, SEQ ID NO:78, SEQ ID NO:79, or SEQ ID NO:80. The fusion protein may comprise or consist of a sequence selected from SEQ ID NO:85, SEQ ID NO:88, SEQ ID NO:91, SEQ ID NO:94 or SEQ ID NO:97. [0138] According to the present invention, the fusion proteins demonstrate advantageous biological properties including improved solubility, stability and/or improved serum half-life. The examples show that the described molecules are very stable in both temperature and chemical stress, showing unfolding only when incubated at temperature higher than 70°C with no aggregation up to 95°C with Tm1 around 67°C. Improved half-life allows for less frequent dosing (a single administration in comparison to existing treatments where daily administration is required). This effect is demonstrated whilst showing strong analgesic effects. In certain embodiments, the fusion protein of the invention has a half-life in-vivo of about or more than any one of 2, 4, 6, 8,10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148, 150, 152,154, 156, 158, 160, 62, 164, 166, 168, 170, 172, 174, 176, 178, 180, 182, 184, 186, 188, 190, 192, 194, 196, 198, 200, 202, 204, 206, 208 or 210 hours +/- 1 hour, further preferably the p75NTR(NBP)-Fc fusion protein of the invention has a half-life in-vivo of about or more than 24 hours. [0139] In another embodiment, the fusion protein of the invention has a half-life in-vitro of about or more than any one of 2, 4, 6, 8,10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148, 150, 152,154, 156, 158, 160, 62, 164, 166, 168, 170, 172, 174, 176, 178, 180, 182, 184, 186, 188, 190, 192, 194, 196, 198, 200, 202, 204, 206, 208 or 210 days +/- 1 day, further the fusion protein has a half-life in-vitro of about or more than 6 days or more than 1 month. In one embodiment, the half-life is 14 days. [0140] According to the foregoing preferred embodiments, the in-vivo half-life can be the half-life in rat or in the corresponding companion animal, e.g., in a dog or cat or horse or pig or camel, or in a human. [0141] Fusion proteins of the invention can operate at a very low dose, but are highly efficacious. [0142] According to the present invention, the fusion proteins display a good safety profile. This is, for example, where subjects maintain normal body weight and hematological parameters and do not generate anti-Drug Antibodies after administration of fusion proteins. [0143] In another aspect, the invention relates to an isolated nucleic acid encoding a fusion protein as described above, for example a nucleic acid encoding a fusion protein such as SEQ ID NO:47, SEQ ID NO:50, SEQ ID NO:53, SEQ ID NO:56 or SEQ ID NO:59, SEQ ID NO:60, SEQ ID NO:62, SEQ ID NO:64, SEQ ID NO:66, SEQ ID NO:68, SEQ ID NO:70, SEQ ID NO:85, SEQ ID NO:88, SEQ ID NO:91, SEQ ID NO:94 or SEQ ID NO:97. In one embodiment, the nucleic acid comprises or consists of a sequence selected from SEQ ID NO:48, SEQ ID NO:51, SEQ ID NO:54, SEQ ID NO:57 or SEQ ID NO:60. In one embodiment, the nucleic acid comprises or consists of a sequence selected from SEQ ID NO:86, SEQ ID NO:89, SEQ ID NO:92, SEQ ID NO:95, or SEQ ID NO:98. [0144] In another aspect, the invention relates to a vector, plasmid, vector, transcription, expression cassette or construct comprising a nucleic acid described above. [0145] In another aspect, the invention relates to a host cell comprising a nucleic acid vector, plasmid, vector, transcription, expression cassette or construct as described above. Suitable host cells are described elsewhere herein. [0146] In another embodiment, the P75NTR protein, portion thereof or fusion protein is labelled with a detectable or functional label. A label can be any molecule that produces or can be induced to produce a signal, including but not limited to fluorophores, fluorescers, radiolabels, enzymes, chemiluminescers, a nuclear magnetic resonance active label or photosensitizers. Thus, the binding may be detected and/or measured by detecting fluorescence or luminescence, radioactivity, enzyme activity or light absorbance. Pharmaceutical Compositions [0147] In another aspect, there is provided a pharmaceutical composition comprising an isolated polypeptide comprising a p75 neurotrophin receptor (p75NTR) extracellular domain, comprising a variant amino acid at one or more of position 75, 109, 133 and/or 134 within said p75NTR, or a fusion protein of the invention. The fusion protein or pharmaceutical composition described herein can be administered by any convenient route, including but not limited to oral, topical, parenteral, sublingual, rectal, vaginal, ocular, intranasal, pulmonary, intradermal, intravitrial, intratumoural, intramuscular, intraperitoneal, intravenous, subcutaneous, intracerebral, transdermal, transmucosal, by inhalation, or topical, particularly to the ears, nose, eyes, or skin or by inhalation. In another embodiment, delivery is of the nucleic acid encoding the drug, e.g., a nucleic acid encoding the molecule of the invention is delivered. [0148] Parenteral administration includes, for example, intravenous, intramuscular, intraarterial, intraperitoneal, intranasal, rectal, intravesical, intradermal, topical, intra-articular or subcutaneous administration. Preferably, the compositions are administered parenterally. [0149] The pharmaceutically acceptable carrier or vehicle can be particulate, so that the compositions are, for example, in tablet or powder form. The term “carrier” refers to a diluent, adjuvant or excipient, with which a drug antibody conjugate of the present invention is administered. Such pharmaceutical carriers can be liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. The carriers can be saline, gum acacia, gelatin, starch paste, talc, keratin, colloidal silica, urea, and the like. In addition, auxiliary, stabilizing, thickening, lubricating and coloring agents can be used. In one embodiment, when administered to a subject, the polypeptide of the present invention or compositions and pharmaceutically acceptable carriers are sterile. Water is a preferred carrier when the drug antibody conjugates of the present invention are administered intravenously. Saline solutions and aqueous dextrose and glycerol solutions can also be employed as liquid carriers, particularly for injectable solutions. Suitable pharmaceutical carriers also include excipients such as starch, glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silica gel, sodium stearate, glycerol monostearate, talc, sodium chloride, dried skim milk, glycerol, propylene, glycol, water, ethanol and the like. The present compositions, if desired, can also contain minor amounts of wetting or emulsifying agents, or pH buffering agents. [0150] The pharmaceutical composition can be in the form of a liquid, e.g., a solution, syrup, solution, emulsion or suspension. The liquid can be useful for oral administration or for delivery by injection, infusion (e.g., IV infusion) or sub-cutaneous. [0151] When intended for oral administration, the composition can be in solid or liquid form, where semi-solid, semi-liquid, suspension and gel forms are included within the forms considered herein as either solid or liquid. [0152] As a solid composition for oral administration, the composition can be formulated into a powder, granule, compressed tablet, pill, capsule, chewing gum, wafer or the like form. Such a solid composition typically contains one or more inert diluents. In addition, one or more of the following can be present: binders such as carboxymethylcellulose, ethyl cellulose, microcrystalline cellulose, or gelatin; excipients such as starch, lactose or dextrins, disintegrating agents such as alginic acid, sodium alginate, corn starch and the like; lubricants such as magnesium stearate; glidants such as colloidal silicon dioxide; sweetening agents such as sucrose or saccharin; a flavoring agent such as peppermint, methyl salicylate or orange flavoring; and a coloring agent. When the composition is in the form of a capsule (e. g. a gelatin capsule), it can contain, in addition to materials of the above type, a liquid carrier such as polyethylene glycol, cyclodextrin or a fatty oil. [0153] When intended for oral administration, a composition can comprise one or more of a sweetening agent, preservatives, dye/colorant and flavor enhancer. In a composition for administration by injection, one or more of a surfactant, preservative, wetting agent, dispersing agent, suspending agent, buffer, stabilizer and isotonic agent can also be included. [0154] Compositions can take the form of one or more dosage units. [0155] In specific embodiments, it can be desirable to administer the composition locally to the area in need of treatment, or by intravenous injection or infusion. [0156] The amount of the polypeptide, fusion protein or pharmaceutical composition described herein that is effective/active in the treatment of a particular disease or condition will depend on the nature of the disease or condition and can be determined by standard clinical techniques. In addition, in vitro or in vivo assays can optionally be employed to help identify optimal dosage ranges. The precise dose to be employed in the compositions will also depend on the route of administration, and the seriousness of the disease or disease, and should be decided according to the judgment of the practitioner and each patient’s circumstances. Factors like age, body weight, sex, diet, time of administration, rate of excretion, condition of the host, drug combinations, reaction sensitivities and severity of the disease shall be taken into account. [0157] Typically, the amount is at least about 0.01% of a polypeptide of the present invention by weight of the composition. When intended for oral administration, this amount can be varied to range from about 0.1 % to about 80% by weight of the composition. Preferred oral compositions can comprise from about 4% to about 50% of the polypeptide of the present invention by weight of the composition. [0158] Compositions can be prepared so that a parenteral dosage unit contains from about 0.01 % to about 2% by weight of the polypeptide of the present invention. [0159] For therapeutic uses the composition may comprise from about 0.01 mg/kg to 250 mg/kg, 0.05 mg/kg to 250 mg/kg, 0.1 mg/kg to 250 mg/kg, 0.5 mg/kg to 250 mg/kg, 1 mg/kg to 250 mg/kg, 0.01 mg/kg to 100 mg/kg, 0.05 mg/kg to 100 mg/kg, 0.1 mg/kg to 100 mg/kg, 0.5 mg/kg to 100 mg/kg, 1 mg/kg to 100 mg/kg, 0.01 mg/kg to 50 mg/kg, 0.05 mg/kg to 50 mg/kg, 0.1 mg/kg to 50 mg/kg, 0.5 mg/kg to 50 mg/kg, 1 mg/kg to 50 mg/kg, 0.01 mg/kg to 20 mg/kg, 0.05 mg/kg to 20 mg/kg, 0.1 mg/kg to 20 mg/kg, 0.5 mg/kg to 20 mg/kg, 1 mg/kg to 20 mg/kg. For administration by injection, the composition can comprise from about typically about 0.1 mg/kg to about 250 mg/kg of the subject’s body weight, preferably, between about 0.1 mg/kg and about 20 mg/kg of the subject’s body weight, and more preferably about 1 mg/kg to about 10 mg/kg of the subject’s body weight. In one embodiment, the composition is administered at a dose of about 1 to 30 mg/kg, e.g., about 5 to 25 mg/kg, about 10 to 20 mg/kg, about 1 to 5 mg/kg, or about 3 mg/kg. The dosing schedule can vary from e.g., once a week to once every 2, 3, or 4 weeks or more. [0160] Treatment can for example be once a month or bi-monthly. This is advantageous over daily administration as this improves compliance and minimizes stress to the subject. [0161] As used herein, “treat”, “treating” or “treatment” means inhibiting or relieving a disease or disease. For example, treatment can include a postponement of development of the symptoms associated with a disease or disease, and/or a reduction in the severity of such symptoms that will, or are expected, to develop with said disease. The terms include ameliorating existing symptoms, preventing additional symptoms, and ameliorating or preventing the underlying causes of such symptoms. Thus, the terms denote that a beneficial result is being conferred on at least some of the subjects being treated. Many medical treatments are effective for some, but not all, patients that undergo the treatment. [0162] The term “subject” or “patient” refers to a human or animal which is the object of treatment, observation, or experiment, suitably a human or a companion animal, such as a canine or a feline, or an animal such as horse, cow, pig, or camel. Therapeutic Uses [0163] In another aspect, the invention relates to the use of an isolated polypeptide comprising a p75NTR protein or portion thereof, fusion protein or pharmaceutical composition described herein in the treatment or prevention of a disease. In another aspect, the disclosure relates to the use of a polypeptide, fusion protein or pharmaceutical composition described herein in the manufacture of a medicament for the treatment or prevention of a disease as listed herein. The invention further relates to a method of treating a disease in a subject comprising an effective amount of the polypeptide, fusion protein or pharmaceutical composition as described herein to said subject. The invention further relates to an isolated polypeptide comprising a p75NTR protein described herein or a fusion protein described herein for use in the treatment or prevention of a disease listed herein. [0164] For example, the disease is a NGF related disorder. For example, the disease is a pro-NGF related disorder. [0165] In one embodiment, the NGF related disorder is selected from the group consisting of: cardiovascular diseases, atherosclerosis, obesity, type 2 diabetes, metabolic syndrome, pain and inflammation. In one embodiment, the NGF related disorder comprises pain. In one embodiment, the pharmaceutical composition is used in the treatment of pain. In one embodiment, the pharmaceutical composition is used for the treatment of a pain and the type of pain is selected from osteoarthritis pain, rheumatoid arthritis pain, surgical and postsurgical pain, incisional pain, general inflammatory pain, cancer pain, pain from trauma, neuropathic pain, neuralgia, diabetic neuropathy pain, pain associated with rheumatic diseases, pain associated with musculoskeletal diseases, visceral pain, and gastrointestinal pain. In one embodiment, the pain comprises osteoarthritis pain. In one embodiment, the pain comprises surgical and post-surgical pain. In one embodiment, the pain comprises cancer pain. [0166] In one or more embodiments, the isolated polypeptide comprising a p75 neurotrophin receptor (p75NTR) extracellular domain, comprising a variant amino acid at one or more of position 75, 109, 133 and/or 134 within said p75NTR, fusion protein or pharmaceutical composition of the invention is for use in a human, canine, feline equine, bovine, or camelid. In one or more embodiments, the p75NTR protein or portion thereof, fusion protein or pharmaceutical composition of the invention is for use in a canine. In one or more embodiments, the p75NTR protein or portion thereof, fusion protein or pharmaceutical composition of the invention is for use in a feline. In one or more embodiments, the variant p75NTR protein or portion thereof, fusion protein or pharmaceutical composition of the invention is for use in an equine. In one or more embodiments, the p75NTR protein or portion thereof, fusion protein or pharmaceutical composition of the invention is for use in a bovine. In one or more embodiments, the p75NTR protein or portion thereof, fusion protein or pharmaceutical composition of the invention is for use in a cameline. In one or more embodiments, the p75NTR protein or portion thereof, fusion protein or pharmaceutical composition of the invention is for use a human. [0167] In one embodiment, the isolated polypeptide comprising a p75 neurotrophin receptor (p75NTR) extracellular domain, comprising a variant amino acid at one or more of position 75, 109, 133 and/or 134 within said p75NTR, fusion protein or pharmaceutical composition of the invention is administered together with one or more therapeutic agent, for example a therapeutic agent to treat pain. [0168] The p75NTR proteins of the invention are optionally administered in combination with one or more active agents including other analgesic agents. Such active agents include analgesic, anti-histamine, antipyretic, anti-inflammatory, antibiotic, antiviral, and anti- cytokine agents. Active agents include agonists, antagonists, and modulators of TNF-α, IL-2, IL-4, IL-6, IL-10, IL-12, IL-13, IL-18, IFN-α, IFN-γ, BAFF, CXCL13, IP-10, VEGF, EPO, EGF, HRG, Hepatocyte Growth Factor (HGF), Hepcidin, including antibodies reactive against any of the foregoing, and antibodies reactive against any of their receptors. Active agents also include, without limitation, 2-arylpropionic acids, aceclofenac, acemetacin, acetylsalicylic acid (Aspirin), alclofenac, alminoprofen, amoxiprin, ampyrone, arylalkanoic acids, azapropazone, benorylate/benorilate, benoxaprofen, bromfenac, carprofen, celecoxib, choline magnesium salicylate, clofezone, COX-2 inhibitors, dexibuprofen, dexketoprofen, diclofenac, diflunisal, droxicam, ethenzamide, etodolac, etoricoxib, faislamine, fenamic acids, fenbufen, fenoprofen, flufenamic acid, flunoxaprofen, flurbiprofen, ibuprofen, ibuproxam, indometacin, indoprofen, kebuzone, ketoprofen, ketorolac, lomoxicam, loxoprofen, lumiracoxib, magnesium salicylate, meclofenamic acid, mefenamic acid, meloxicam, metamizole, methyl salicylate, mofebutazone, nabumetone, naproxen, n-arylanthranilic acids, oxametacin, oxaprozin, oxicams, oxyphenbutazone, parecoxib, phenazone, phenylbutazone, phenylbutazone, piroxicam, pirprofen, profens, proglumetacin, pyrazolidine derivatives, rofecoxib, salicyl salicylate, salicylamide, salicylates, sulfinpyrazone, sulindac, suprofen, tenoxicam, tiaprofenic acid, tolfenamic acid, tolmetin, and valdecoxib. [0169] An anti-histamine can be any compound that opposes the action of histamine or its release from cells (e.g., mast cells). Anti-histamines include but are not limited to acrivastine, astemizole, azatadine, azelastine, betatastine, brompheniramine, buclizine, cetirizine, cetirizine analogues, chlorpheniramine, clemastine, CS 560, cyproheptadine, desloratadine, dexchlorpheniramine, ebastine, epinastine, fexofenadine, HSR 609, hydroxyzine, levocabastine, loratidine, methscopolamine, mizolastine, norastemizole, phenindamine, promethazine, pyrilamine, terfenadine, and tranilast. [0170] Antibiotics include but are not limited to amikacin, aminoglycosides, amoxicillin, ampicillin, ansamycins, arsphenamine, azithromycin, azlocillin, aztreonam, bacitracin, carbacephem, carbapenems, carbenicillin, cefaclor, cefadroxil, cefalexin, cefalothin, cefalotin, cefamandole, cefazolin, cefdinir, cefditoren, cefepime, cefixime, cefoperazone, cefotaxime, cefoxitin, cefpodoxime, cefprozil, ceftazidime, ceftibuten, ceftizoxime, ceftobiprole, ceftriaxone, cefuroxime, cephalosporins, chloramphenicol, cilastatin, ciprofloxacin, clarithromycin, clindamycin, cloxacillin, colistin, co-trimoxazole, dalfopristin, demeclocycline, dicloxacillin, dirithromycin, doripenem, doxycycline, enoxacin, ertapenem, erythromycin, ethambutol, flucloxacillin, fosfomycin, furazolidone, fusidic acid, gatifloxacin, geldanamycin, gentamicin, glycopeptides, herbimycin, imipenem, isoniazid, kanamycin, levofloxacin, lincomycin, linezolid, lomefloxacin, loracarbef, macrolides, mafenide, meropenem, meticillin, metronidazole, mezlocillin, minocycline, monobactams, moxifloxacin, mupirocin, nafcillin, neomycin, netilmicin, nitrofurantoin, norfloxacin, ofloxacin, oxacillin, oxytetracycline, paromomycin, penicillin, penicillins, piperacillin, platensimycin, polymyxin B, polypeptides, prontosil, pyrazinamide, quinolones, quinupristin, rifampicin, rifampin, roxithromycin, spectinomycin, streptomycin, sulfacetamide, sulfamethizole, sulfanilimide, sulfasalazine, sulfisoxazole, sulfonamides, teicoplanin, telithromycin, tetracycline, tetracyclines, ticarcillin, tinidazole, tobramycin, trimethoprim, trimethoprim-sulfamethoxazole, troleandomycin, trovafloxacin, and vancomycin. [0171] Active agents also include aldosterone, beclometasone, betamethasone, corticosteroids, cortisol, cortisone acetate, deoxycorticosterone acetate, dexamethasone, fludrocortisone acetate, glucocorticoids, hydrocortisone, methylprednisolone, prednisolone, prednisone, steroids, and triamcinolone. Any suitable combination of these active agents is also contemplated. [0172] The most common form of current treatment for OA and pain related to OA is NSAIDs (which are also anti-pain medications). NSAIDs are not always sufficiently effective, typically need to be administered daily and none are approved for long-term use in cats in the US. Additionally, there are safety and tolerability concerns with the use of NSAIDS in both dogs and cats, especially with long-term treatment. NSAIDs are not recommended to be co-administered with anti-NGF mAbs for long periods. [0173] In certain embodiments, treatment comprises coadministration of dietary supplements containing Omega-3 fatty acids, microlactin, and/or glucosamine/chondroitin as an aid to joint health. Adequan (polysulfated glycosaminoglycan) is an FDA-approved disease modifying drug that inhibits cartilage loss and may also be co-administered. [0174] The isolated polypeptide comprising a p75 neurotrophin receptor (p75NTR) extracellular domain, comprising a variant amino acid at one or more of position 75, 109, 133 and/or 134 within said p75NTR fusion protein or pharmaceutical composition may be administered at the same time or at a different time as the other therapy or therapeutic compound or therapy, e.g., simultaneously, separately or sequentially. [0175] In another aspect, the invention relates to the use of an isolated polypeptide comprising a p75NTR protein or portion thereof, fusion protein or pharmaceutical composition comprising said isolated polypeptide or fusion protein in the treatment or prevention of osteoarthritis. In another aspect, the disclosure relates to an isolated polypeptide comprising a p75NTR protein or portion thereof, fusion protein or pharmaceutical composition comprising said isolated polypeptide or fusion protein in the manufacture of a medicament for the treatment or prevention of osteoarthritis. The invention further relates to a method of treating osteoarthritis in a subject comprising an effective amount of an isolated polypeptide comprising a p75NTR protein or portion thereof, fusion protein or pharmaceutical composition comprising said isolated polypeptide or fusion protein to said subject. The invention further relates to an isolated polypeptide comprising a p75NTR protein or portion thereof, fusion protein or pharmaceutical composition comprising said isolated polypeptide or fusion protein for use in the treatment or prevention of osteoarthritis. [0176] The “subject” or “patient” in recipient of the method, use or p75NTR protein or a portion thereof or composition comprising said p75NTR protein or a portion thereof for the treatment of osteoarthritis refers to a human or animal which is the object of treatment, observation, or experiment, suitably a human or a companion animal, such as a canine or a feline. Other animals which may be suitable for treatment include but are not limited to cow, pig, horse, camel. [0177] The p75NTR protein or a portion thereof refers a p75NTR protein or a portion thereof suitable for administration to said subject. Preferably the p75NTR protein or a portion thereof is obtained from the same species as the subject in receipt of p75NTR protein or a portion thereof or composition comprising said p75NTR protein or a portion thereof. [0178] In one embodiment the p75NTR protein or a portion thereof is for treatment of an animal such as a cat, dog, pig, cow, horse or camel. In one embodiment the companion animal is a dog. In one embodiment the companion animal is a cat. In one embodiment the p75NTR protein or a portion thereof or the pharmaceutical composition for use in the treatment of osteoarthritis comprises a canine p75NTR protein such as SEQ ID NO.1. In one embodiment the p75NTR protein or a portion thereof or the pharmaceutical composition for use in the treatment of osteoarthritis comprises a feline p75NTR protein, such as SEQ ID NO.3. In one embodiment the p75NTR protein or a portion thereof or the pharmaceutical composition for use in the treatment of osteoarthritis comprises a bovine p75NTR protein, such as SEQ ID NO: 36. In one embodiment the p75NTR protein or a portion thereof or the pharmaceutical composition for use in the treatment of osteoarthritis comprises a camelid p75NTR protein, such as SEQ ID NO: 99. In one embodiment the p75NTR protein or a portion thereof or the pharmaceutical composition for use in the treatment of osteoarthritis comprises a porcine p75NTR protein, such as SEQ ID NO: 108. In one embodiment the p75NTR protein or a portion thereof or the pharmaceutical composition for use in the treatment of osteoarthritis comprises an equine p75NTR protein, such as SEQ ID NO: 5. In one embodiment the p75NTR protein or a portion thereof is for treatment of a human and the p75NTR protein or a portion thereof or the pharmaceutical composition for use in the treatment of osteoarthritis comprises a human p75NTR protein, such as SEQ ID NO: 71. [0179] In one embodiment the p75NTR protein or a portion thereof for use in the treatment of osteoarthritis comprises the extracellular domain or part thereof. In one embodiment the treatment is for a dog and the p75NTR extracellular domain comprises SEQ ID NO. 7. As described herein a portion of the extracellular domain may be used for example SEQ ID NO: 34. In an embodiment the treatment is for a cat and the p75NTR extracellular domain comprises SEQ ID NO. 38. In an embodiment the treatment is for a human and the p75NTR extracellular domain comprises SEQ ID NO: 73. In an embodiment the p75NTR extracellular domain comprises a camel p75NTR extracellular domain such as SEQ ID NO: 101. In an embodiment the p75NTR extracellular domain comprises a pig p75NTR extracellular domain such as SEQ ID NO: 110. In an embodiment the p75NTR extracellular domain comprises an equine p75NTR extracellular domain such as SEQ ID NO: 118. In an embodiment the p75NTR extracellular domain comprises a bovine p75NTR extracellular domain such as SEQ ID NO: 125.In an embodiment the p75NTR protein or portion thereof may comprise any one of the variant p75NTR proteins, fusion proteins, or pharmaceutical compositions as described herein above. [0180] The p75NTR protein or portion thereof for use in the treatment of osteoarthritis may be provided as a fusion protein. The fusion protein comprising an isolated companion animal p75NTR extracellular domain or portion thereof and a half-life extending moiety. For example, the p75NTR extracellular domain of SEQ ID NO: 7, 38, 73, 101, 110, 118 or 125 may be joined to a half-life extending moiety. Suitable half-life extending moieties are described herein and may be used in the fusion protein, for example an Fc domain, a serum albumin binder or PEG. [0181] In embodiments where a fusion protein comprising an Fc domain is used in the treatment of osteoarthritis, the Fc domain and the p75NTR extracellular domain or portion thereof and the Fc domain are linked with a linker. In an embodiment the linker is a peptide linker, for example the peptide linker is (GGGG)n or (G4S)n wherein n is 1 to 4. [0182] In an embodiment, the fusion protein for use in the treatment of osteoarthritis comprises a canine extracellular domain for example SEQ ID NO: 7 or a portion thereof for example SEQ ID NO: 34. The portion of the canine extracellular domain in SEQ ID NO: 34 comprises the canine ECD without stalk and without alpha and gamma secretase cleavage 3’ of the stalk region. [0183] The Fc domain present in the fusion protein may be a canine Fc domain. In some embodiments, the fusion protein for use in the treatment of osteoarthritis comprises SEQ ID NO: 11 or SEQ ID NO: 13. In some embodiments, the fusion protein for use in the treatment of osteoarthritis comprises SEQ ID NO: 11. In some embodiments the fusion protein for use in the treatment of osteoarthritis comprises a variant canine p75NTR ECD with a variant amino acid at one or more of position 75, 109, 133 and/or 134, as described herein for example the fusion protein may comprise or consist of SEQ ID NO: 47, SEQ ID NO:50, SEQ ID NO:53, SEQ ID NO:56 or SEQ ID NO:59. In some embodiments the fusion protein may comprise or consist of SEQ ID NO:47 or SEQ ID NO:59. [0184] The Fc domain present in the fusion protein may be a feline Fc domain. In an exemplary embodiment, the fusion protein for use in the treatment of osteoarthritis comprises SEQ ID NO: 39, SEQ ID NO: 42 or SEQ ID NO: 44. In some embodiments, the fusion protein for use in the treatment of osteoarthritis comprises SEQ ID NO: 42. In some embodiments the fusion protein for use in the treatment of osteoarthritis comprises a variant feline p75NTR ECD with a variant amino acid at one or more of position 75, 109, 133 and/or 134, as described herein for example the fusion protein may comprise or consist of SEQ ID NO:62, SEQ ID NO:64, SEQ ID NO:66, SEQ ID NO:68 or SEQ ID NO:70. In some embodiments the fusion protein may comprise or consist of SEQ ID NO:62 or SEQ ID NO:70. [0185] The Fc domain present in the fusion protein may be a human Fc domain. In an exemplary embodiment, the fusion protein for use in the treatment of osteoarthritis comprises SEQ ID NO: 81, SEQ ID NO: 82 or SEQ ID NO: 83. In some embodiments the fusion protein for use in the treatment of osteoarthritis comprises a variant feline p75NTR ECD with a variant amino acid at one or more of position 75, 109, 133 and/or 134, as described herein for example the fusion protein may comprise or consist of SEQ ID NO:85, SEQ ID NO:88, SEQ ID NO:91, SEQ ID NO:94 or SEQ ID NO:97. In some embodiments the fusion protein may comprise or consist of SEQ ID NO:85 or SEQ ID NO:97. [0186] The p75NTR molecules for use in the treatment of osteoarthritis are capable of binding pro-NGF and/or NGF. It the treatment of osteoarthritis it may be advantageous to use a molecule which preferentially binds pro-NGF over NGF. As shown herein in the Examples p75NTR comprising a variant amino acid at position 75 may preferentially bind pro-NGF over NGF. In an embodiment the isolated polypeptide comprising a p75NTR protein or portion thereof, fusion protein, for use in the treatment of osteoarthritis comprises a variant amino acid at position 75. [0187] Treatment of osteoarthritis may be measured by a number of factors for example treatment of osteoarthritis may comprise the slowing or arresting of disease progression, reversal of disease progression, regrowth of cartilage and/or curative treatment. In some embodiments treatment of osteoarthritis is determined by the rate of cartilage loss or regrowth. [0188] In an embodiment the treatment for osteoarthritis comprises prophylactic treatment. Prophylactic treatment may comprise preventative treatment in order to prevent onset of a disease. As such treatment may be provided to a subject prior to the onset of symptoms. [0189] In an embodiment the treatment for osteoarthritis comprises administration of a second compound. Suitable additional therapeutic compounds are described herein above. [0190] In an embodiment the treatment for osteoarthritis further comprises the treatment of one or more NGF-related disorders in a companion animal. In an embodiment, administration of the p75NTR protein, portion thereof or fusion protein results in the treatment of both osteoarthritis and one or more NGF-related disorder. Advantageously the molecules described herein have shown to have both disease modifying osteoarthritis activity and anti- inflammatory activity. In one embodiment the one or more NGF-related disorders are cardiovascular diseases, atherosclerosis, obesity, type 2 diabetes, metabolic syndrome, pain and inflammation. In one embodiment the NGF-related disorder is a pain related disorder. In one embodiment the pain is selected from osteoarthritis pain, rheumatoid arthritis pain, surgical and postsurgical pain, incisional pain, general inflammatory pain, cancer pain, pain from trauma, neuropathic pain, neuralgia, diabetic neuropathy pain, pain associated with rheumatic diseases, pain associated with musculoskeletal diseases, visceral pain, and gastrointestinal pain. [0191] The molecules of the invention may therefore advantageously be used to treat both osteoarthritis and provide an analgesic effect. Similarly, molecules of the invention may therefore advantageously be used to treat both inflammation and provide an analgesic effect. This is advantageous as subjects with osteoarthritis or inflammation may also suffer from pain. Suitable molecules may include SEQ ID NO: 11 as demonstrated in Example 11 and 12 as well as lower affinity molecules such as SEQ ID NO:47 or SEQ ID NO:59 for the treatment of dogs. Similarly, suitable molecules may include SEQ ID NO:42 as well as lower affinity molecules such as SEQ ID NO:62 or SEQ ID NO:70 for the treatment of cats. [0192] In an embodiment the treatment of osteoarthritis also comprises the treatment of an NGF-related disorder such as inflammation. In one embodiment the inflammation is an inflammatory disease, condition, or symptom. In one embodiment the inflammatory disease, condition, or symptom is selected from the group consisting of single or multiple organ failure or dysfunction, sepsis, cytokine storm, fever, neurological dysfunction or impairment, loss of taste or smell, cardiac dysfunction, pulmonary dysfunction, liver dysfunction, acute or chronic respiratory dysfunction, graft versus host disease (GVHD), cardiomyopathy, vasculitis, fibrosis, ophthalmic inflammation, dermatologic inflammation, gastrointestinal inflammation, tendinopathies, allergy, asthma, glomerulonephritis, pancreatitis, hepatitis, non-alcoholic steatohepatitis (NASH), inflammatory arthritis, gout, multiple sclerosis, psoriasis, acute respiratory distress syndrome (ARDS), diabetic ulcers, non-healing wounds, lupus, autoimmune diseases associated with acute or chronic inflammation, and acute or chronic inflammation associated with viral, bacterial or fungal infection, swelling, tenderness, joint stiffness or decrease in joint mobility. In one embodiment the inflammation is systemic. In one embodiment the inflammation is local. Further Methods and Kits [0193] The invention also provides an in vitro, ex vivo or in vivo method for inhibiting NGF activity in a subject comprising administering the isolated polypeptide comprising a p75 neurotrophin receptor (p75NTR) extracellular domain, comprising a variant amino acid at one or more of position 75, 109, 133 and/or 134 within said p75NTR, fusion protein or pharmaceutical composition of the invention. In one or more aspects, the present invention provides a method of producing the fusion protein of the invention by culturing the host cell of the invention under conditions that result in production of the fusion protein and subsequently isolating the fusion protein from the host cell or culture medium of the host cell. [0194] In another aspect, the invention provides a kit for the treatment or prevention of a disease, diagnosis, prognosis or monitoring disease comprising the isolated polypeptide comprising a p75 neurotrophin receptor (p75NTR) extracellular domain comprising a variant amino acid at one or more of positions 75, 109, 133 and/or 134 within said p75NTR, fusion protein or pharmaceutical composition of the invention. Such a kit may contain other components, packaging and/or instructions. [0195] The invention in another aspect provides an isolated polypeptide comprising a p75 neurotrophin receptor (p75NTR) extracellular domain, comprising a variant amino acid at one or more of position 75, 109, 133 and/or 134 within said p75NTR, fusion protein or pharmaceutical composition of the invention packaged in lyophilized form or packaged in an aqueous medium. [0196] In another aspect, isolated polypeptide comprising a p75 neurotrophin receptor (p75NTR) extracellular domain, comprising a variant amino acid at one or more of position 75, 109, 133 and/or 134 within said p75NTR, fusion protein or pharmaceutical composition of the invention as described herein is used for non-therapeutic purposes, such as diagnostic tests and assays. Thus, the present invention also provides the above p75NTR proteins and fusion proteins for use in diagnostic methods for detecting NGF in a subject, particularly a human, canine or feline subject but not limited thereto, known to be or suspected of having an NGF related disorder. Methods for detecting NGF in a subject known to be or suspected of having an NGF related disorder may include exposing a sample from the subject to a labelled protein of the invention and detecting said labelled protein. A diagnostic method may be used to quantitatively or qualitatively detect the NGF in a sample or to detect presence of cells that express the NGF. [0197] Further aspects and embodiments of the invention will be apparent to those skilled in the art given the present disclosure including the following experimental exemplification. [0198] Unless otherwise defined herein, scientific and technical terms used in connection with the present disclosure shall have the meanings that are commonly understood by those of ordinary skill in the art. While the foregoing disclosure provides a general description of the subject matter encompassed within the scope of the present invention, including methods, as well as the best mode thereof, of making and using this invention, the following examples are provided to further enable those skilled in the art to practice this invention and to provide a complete written description thereof. However, those skilled in the art will appreciate that the specifics of these examples should not be read as limiting on the invention, the scope of which should be apprehended from the claims and equivalents thereof appended to this disclosure. Various further aspects and embodiments of the present invention will be apparent to those skilled in the art in view of the present disclosure. [0199] All documents mentioned in this specification are incorporated herein by reference in their entirety, including any references to gene accession numbers and references to patent publications. [0200] “and/or” where used herein is to be taken as specific disclosure of each of the two specified features or components with or without the other. For example, “A and/or B” is to be taken as specific disclosure of each of (i) A, (ii) B and (iii) A and B, just as if each is set out individually herein. Unless context dictates otherwise, the descriptions and definitions of the features set out above are not limited to any particular aspect or embodiment of the invention and apply equally to all aspects and embodiments which are described. Numbered Clauses 1. An isolated polypeptide comprising a companion animal p75 neurotrophin receptor (p75NTR) extracellular domain, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134. 2. The isolated polypeptide according to clause 1, wherein the variant amino acid at position 75 of p75NTR comprises a polar side chain. 3. The isolated polypeptide according to any preceding clause, wherein the variant amino acid at position 75 of p75NTR is selected from selected from serine, threonine, tyrosine, tryptophan, asparagine, glutamine or cysteine, preferably threonine. 4. The isolated polypeptide according to any preceding clause, wherein the variant amino acid at position 109 of p75NTR comprises an aromatic side chain. The isolated polypeptide according to any preceding clause, wherein the variant amino acid at position 109 of p75NTR is selected from histidine, tyrosine, phenylalanine, or tryptophan. The isolated polypeptide according to any preceding clause, wherein the variant amino acid at position 133 of p75NTR comprises a charged side chain. The isolated polypeptide according to any preceding clause, wherein the variant amino acid at position 133 of p75NTR is selected from arginine, histidine, lysine, aspartic acid, or glutamic acid. The isolated polypeptide according to any of clauses 1 to 6, wherein the variant amino acid at position 133 of p75NTR comprises a negatively charged side chain. The isolated polypeptide according to clause 8, wherein the variant amino acid at position 133 of p75NTR is selected from arginine, histidine, or lysine, preferably arginine. The isolated polypeptide according to any preceding clause, wherein the variant amino acid at position 134 of p75NTR comprises a hydrophobic side chain. The isolated polypeptide according to any preceding clause, wherein the variant amino acid at position 134 of p75NTR is selected from alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine, or tryptophan. The isolated polypeptide according to any of clauses 1 to 10, wherein the variant amino acid at position 134 of p75NTR comprises a non-aromatic hydrophobic side chain. The isolated polypeptide according to clause 12, wherein the variant amino acid at position 134 of p75NTR is selected from alanine, valine, isoleucine, leucine, or methionine, preferably leucine. The isolated polypeptide according to any preceding clause, wherein the companion animal is a cat, dog, pig, cow, horse, or camel. The isolated polypeptide according to any preceding clause, wherein the companion animal is a dog and the p75NTR comprises or consists of a sequence selected from SEQ ID NO:46, SEQ ID NO:49, SEQ ID NO:52, SEQ ID NO:55 or SEQ ID NO:58. The isolated polypeptide according any of clauses 1 to 14, wherein the companion animal is a cat and the p75NTR comprises or consists of a sequence selected from SEQ ID NO:61, SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67 or SEQ ID NO:69. The isolated polypeptide according any of clauses 1 to 14, wherein the companion animal is a pig and the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 112, SEQ ID NO: 113, SEQ ID NO: 114, SEQ ID NO: 115 or SEQ ID NO: 116; wherein the companion animal is a horse and the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 120, SEQ ID NO: 121, SEQ ID NO: 122, SEQ ID NO: 123 or SEQ ID NO: 124; wherein the companion animal is a cow and the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 127, SEQ ID NO: 128, SEQ ID NO: 129, SEQ ID NO: 130 or SEQ ID NO: 131; or wherein the companion animal is a camel and the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 103, SEQ ID NO: 104, SEQ ID NO: 105, SEQ ID NO: 106 or SEQ ID NO: 107. The isolated polypeptide according to a preceding clause wherein the p75NTR extracellular domain is truncated. An isolated nucleic acid encoding the isolated polypeptide according to a preceding clause. A vector comprising a nucleic acid according to clause 19. A host cell comprising a nucleic acid according to clause 19 or a vector according to clause 20. A fusion protein comprising a companion animal p75NTRextracellular domain, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134, and a half-life extending moiety. The fusion protein according to clause 22 wherein the half-life extending moiety is selected from an Fc domain, a serum albumin binder or PEG. The fusion protein according to clause 22 wherein the half-life extending moiety is a wild type or mutant Fc domain. The fusion protein according to any of clauses 22 to 24 wherein the half-life extending moiety is an Fc domain and the p75NTR extracellular domain or portion thereof and the Fc domain are linked with a linker. The fusion protein according to clause 25 wherein the linker is a peptide linker. The fusion protein according to clause 26 wherein the peptide linker is (G₄S)_n wherein n is 1 to 4. The fusion protein according to any of clauses 22 to 27 wherein the companion animal is a cat, dog, pig, cow, horse, or camel. The fusion protein according to any of clauses 22 to 28 wherein the Fc domain is a canine Fc domain. The fusion protein according to clause 29 wherein the fusion protein comprises or consists of a sequence selected from SEQ ID NO:47, SEQ ID NO:50 SEQ ID NO:53, SEQ ID NO:56 or SEQ ID NO:59. The fusion protein according to any of clause 22 to 28 wherein the Fc domain is a feline Fc domain. The fusion protein according to clause 31 wherein the fusion protein comprises or consists of a sequence selected from SEQ ID NO:62, SEQ ID NO:64, SEQ ID NO:66, SEQ ID NO:68 or SEQ ID NO:70. A nucleic acid encoding a fusion protein according to any of clauses 22 to 32. A vector comprising a nucleic acid according to clause 33. A host cell comprising a nucleic acid according to clause 33 or a vector according to clause 34. A pharmaceutical composition comprising an isolated polypeptide according to any of clauses 1 to 18, or a fusion protein according to any of clauses 22 to 32. A method for treating an NGF-related disorder in a companion animal comprising administering an isolated companion animal p75NTR protein according to any of clauses 1 to 18, a fusion protein according to any of clauses 22 to 32 or a pharmaceutical composition of clause 36. The use of an isolated companion animal p75NTR protein according to any of embodiments 1 to 18, a fusion protein according to any of clauses 22 to 32 or a pharmaceutical composition of embodiment 36 in the manufacture of a medicament for the treatment of an NGF-related disorder in a companion animal. An isolated companion animal p75NTR protein according to any of embodiments 1 to 18, or a fusion protein according to any of clauses 22 to 32 for use in the treatment of an NGF- related disorder in a companion animal. The method of clause 37 or the use of clause 38 or the isolated companion animal p75NTR protein or a fusion protein for use according to clause 39 wherein the NGF-related disorder is cardiovascular diseases, atherosclerosis, obesity, type 2 diabetes, metabolic syndrome, pain and inflammation. The method, use or the isolated companion animal p75NTR protein for use according to clause 40 wherein the NGF-related disorder is a pain related disorder. The method, use or the isolated companion animal p75NTR protein for use according to clause 41 wherein pain is selected from osteoarthritis pain, rheumatoid arthritis pain, surgical and postsurgical pain, incisional pain, general inflammatory pain, cancer pain, pain from trauma, neuropathic pain, neuralgia, diabetic neuropathy pain, pain associated with rheumatic diseases, pain associated with musculoskeletal diseases, visceral pain, and gastrointestinal pain. The method or use or the isolated companion animal p75NTR protein for use according to clause 40 wherein the NGF-related disorder is inflammation, wherein the inflammation is an inflammatory disease, condition, or symptom, optionally wherein the inflammatory disease, condition, or symptom is selected from the group consisting of single or multiple organ failure or dysfunction, sepsis, cytokine storm, fever, neurological dysfunction or impairment, loss of taste or smell, cardiac dysfunction, pulmonary dysfunction, liver dysfunction, acute or chronic respiratory dysfunction, graft versus host disease (GVHD), cardiomyopathy, vasculitis, fibrosis, ophthalmic inflammation, dermatologic inflammation, gastrointestinal inflammation, tendinopathies, allergy, asthma, glomerulonephritis, pancreatitis, hepatitis, non-alcoholic steatohepatitis (NASH), inflammatory arthritis, gout, multiple sclerosis, psoriasis, acute respiratory distress syndrome (ARDS), diabetic ulcers, non-healing wounds, lupus, autoimmune diseases associated with acute or chronic inflammation, and acute or chronic inflammation associated with viral, bacterial or fungal infection, swelling, tenderness, joint stiffness or decrease in joint mobility. A method of inhibiting NGF activity in a companion animal comprising administering an isolated companion animal p75NTR protein according to any of clause 1 to 18, a fusion protein according to any of clause 22 to 32 or a pharmaceutical composition of clause 36. The method, use or the isolated companion animal p75NTR protein of any of clauses 41 to 43 or the method of clause 44 comprising administration of a second compound that treats pain. A kit comprising an isolated companion animal p75NTR protein according to any of clauses 1 to 18, a fusion protein according to any of clauses 22 to 32 or a pharmaceutical composition of clause 36 and optionally instructions for use. A method for treating osteoarthritis in a companion animal comprising administering an effective amount of an isolated companion animal p75NTR protein or a portion thereof, or a pharmaceutical composition comprising said isolated companion animal p75NTR protein or a portion thereof. The use of an isolated companion animal p75NTR protein or a portion thereof, or a pharmaceutical composition comprising said isolated companion animal p75NTR protein or a portion thereof for the manufacture of a medicament for in the treatment of osteoarthritis in a companion animal. An isolated companion animal p75NTR protein or a portion thereof, or a pharmaceutical composition comprising said isolated companion animal p75NTR protein or a portion thereof for use in the treatment of osteoarthritis in a companion animal. The method according to clause 47 or use according to clause 48 or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 49, wherein the companion animal is a cat, dog, pig, cow, horse or camel. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 50, wherein the isolated companion animal p75NTR protein or a portion thereof comprises one of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 36, SEQ ID NO: 99, SEQ ID NO: 108. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 47 to 51 wherein the p75NTR protein or a portion thereof comprises the extracellular domain or part thereof. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use for use according to clause 52 wherein the p75NTR extracellular domain comprises one of SEQ ID NO: 7, SEQ ID NO: 38 SEQ ID NO: 101, SEQ ID NO:110, SEQ ID NO: 118 or SEQ ID NO: 125. The method, use, or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 47 to 53, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 54, wherein the variant amino acid at position 75 of p75NTR comprises a polar side chain. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 55, wherein the variant amino acid at position 75 of p75NTR is selected from serine, threonine, tyrosine, tryptophan, asparagine, glutamine or cysteine, preferably threonine. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 56, wherein the variant amino acid at position 109 of p75NTR comprises an aromatic side chain. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 57, wherein the variant amino acid at position 109 of p75NTR is selected from histidine, tyrosine, phenylalanine, or tryptophan. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 58, wherein the variant amino acid at position 133 of p75NTR comprises a charged side chain. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 59, wherein the variant amino acid at position 133 of p75NTR is selected from arginine, histidine, lysine, aspartic acid, or glutamic acid. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 60, wherein the variant amino acid at position 133 of p75NTR comprises a negatively charged side chain. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 61, wherein the variant amino acid at position 133 of p75NTR is selected from arginine, histidine, or lysine, preferably arginine. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 62, wherein the variant amino acid at position 134 of p75NTR comprises a hydrophobic side chain. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 63, wherein the variant amino acid at position 134 of p75NTR is selected from alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine, or tryptophan. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 64, wherein the variant amino acid at position 134 of p75NTR comprises a non-aromatic hydrophobic side chain. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 65, wherein the variant amino acid at position 134 of p75NTR is selected from alanine, valine, isoleucine, leucine, or methionine, preferably leucine. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 66, wherein the companion animal is a cat, dog, pig, cow, horse or camel. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 67, wherein the companion animal is a dog and the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 46, SEQ ID No. SEQ ID NO: 49, SEQ ID No. SEQ ID NO: 52, SEQ ID No. SEQ ID NO: 55 or SEQ ID No. SEQ ID NO: 58. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 67, wherein the companion animal is a cat and the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 61, SEQ ID No. SEQ ID NO: 63, SEQ ID No. SEQ ID NO: 65, SEQ ID No. SEQ ID NO: 67 or SEQ ID No. SEQ ID NO: 69. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 54 to 69 wherein the p75NTR extracellular domain is truncated. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 47 to 70 wherein the isolated companion animal p75NTR protein is provided as a fusion protein comprising said isolated companion animal p75NTR extracellular domain or portion thereof and a half-life extending moiety. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 71, wherein the half-life extending moiety is selected from an Fc domain, a serum albumin binder or PEG. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 72, wherein the half-life extending moiety is a wild type or mutant Fc domain. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of clauses 71 to 73, wherein the half-life extending moiety is an Fc domain and the p75NTR extracellular domain or portion thereof and the Fc domain are linked with a linker. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 74, wherein the linker is a peptide linker. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition according to clause 75, wherein the peptide linker is (GGGG)n or (G4S)n wherein n is 1 to 4. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition according to any one of clauses 71 to 76 wherein the fusion protein comprises one of SEQ ID NO:11, SEQ ID NO:13, SEQ ID NO:39, SEQ ID NO:42, SEQ ID NO:47, SEQ ID NO:50, SEQ ID NO:53, SEQ ID NO:56, SEQ ID NO:59, SEQ ID NO:62, SEQ ID NO:64, SEQ ID NO:66, SEQ ID NO:68, SEQ ID NO:70. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any one of clauses 47 to 77 wherein said treatment of osteoarthritis comprises slowing or arresting of disease progression, reversal of disease progression, regrowth of cartilage and/or curative treatment. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 78 wherein said treatment is determined by the rate of cartilage loss or regrowth. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any one of clauses 47 to 79 wherein said treatment of osteoarthritis further comprises the treatment of one or more NGF-related disorders in a companion animal. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 80 wherein the one or more NGF-related disorders are cardiovascular diseases, atherosclerosis, obesity, type 2 diabetes, metabolic syndrome, pain and inflammation. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 81 wherein the NGF-related disorder is a pain related disorder. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 82 wherein pain is selected from osteoarthritis pain, rheumatoid arthritis pain, surgical and postsurgical pain, incisional pain, general inflammatory pain, cancer pain, pain from trauma, neuropathic pain, neuralgia, diabetic neuropathy pain, pain associated with rheumatic diseases, pain associated with musculoskeletal diseases, visceral pain, and gastrointestinal pain. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 81 wherein the NGF-related disorder is inflammation, wherein the inflammation is an inflammatory disease, condition, or symptom. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to clause 84 wherein the inflammatory disease, condition, or symptom is selected from the group consisting of single or multiple organ failure or dysfunction, sepsis, cytokine storm, fever, neurological dysfunction or impairment, loss of taste or smell, cardiac dysfunction, pulmonary dysfunction, liver dysfunction, acute or chronic respiratory dysfunction, graft versus host disease (GVHD), cardiomyopathy, vasculitis, fibrosis, ophthalmic inflammation, dermatologic inflammation, gastrointestinal inflammation, tendinopathies, allergy, asthma, glomerulonephritis, pancreatitis, hepatitis, non-alcoholic steatohepatitis (NASH), inflammatory arthritis, gout, multiple sclerosis, psoriasis, acute respiratory distress syndrome (ARDS), diabetic ulcers, non-healing wounds, lupus, autoimmune diseases associated with acute or chronic inflammation, and acute or chronic inflammation associated with viral, bacterial or fungal infection, swelling, tenderness, joint stiffness or decrease in joint mobility. 86. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any one of clauses 47 to 85, wherein said treatment comprises prophylactic treatment. 87. The method, use or the isolated companion animal p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any one of clauses 47 to 86, comprising administration of a second compound. Numbered Embodiments 1. An isolated polypeptide comprising a human p75neurotrophin receptor (p75NTR) extracellular domain, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134. 2. The isolated polypeptide according to embodiment 1, wherein the variant amino acid at position 75 of p75NTR comprises a polar side chain. 3. The isolated polypeptide according to any preceding embodiment, wherein the variant amino acid at position 75 of p75NTR is selected from selected from serine, threonine, tyrosine, tryptophan, asparagine, glutamine or cysteine, preferably threonine. 4. The isolated polypeptide according to any preceding embodiment, wherein the variant amino acid at position 109 of p75NTR comprises an aromatic side chain. 5. The isolated polypeptide according to any preceding embodiment, wherein the variant amino acid at position 109 of p75NTR is selected from histidine, tyrosine, phenylalanine, or tryptophan. 6. The isolated polypeptide according to any preceding embodiment, wherein the variant amino acid at position 133 of p75NTR comprises a charged side chain. The isolated polypeptide according to any preceding embodiment, wherein the variant amino acid at position 133 of p75NTR is selected from arginine, histidine, lysine, aspartic acid, or glutamic acid. The isolated polypeptide according to any of embodiments 1 to 6, wherein the variant amino acid at position 133 of p75NTR comprises a negatively charged side chain. The isolated polypeptide according to embodiment 8, wherein the variant amino acid at position 133 of p75NTR is selected from arginine, histidine, or lysine, preferably arginine. The isolated polypeptide according to any preceding embodiment, wherein the variant amino acid at position 134 of p75NTR comprises a hydrophobic side chain. The isolated polypeptide according to any preceding embodiment, wherein the variant amino acid at position 134 of p75NTR is selected from alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine, or tryptophan. The isolated polypeptide according to any of embodiments 1 to 10, wherein the variant amino acid at position 134 of p75NTR comprises a non-aromatic hydrophobic side chain. The isolated polypeptide according to embodiment 12, wherein the variant amino acid at position 134 of p75NTR is selected from alanine, valine, isoleucine, leucine, or methionine, preferably leucine. The isolated polypeptide according to any preceding embodiment, wherein the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 84, SEQ ID NO: 87, SEQ ID NO: 90, SEQ ID NO:93 or SEQ ID NO: 96 The isolated polypeptide according to a preceding embodiment wherein the p75NTR extracellular domain is truncated. An isolated nucleic acid encoding the isolated polypeptide according to a preceding embodiment. A vector comprising a nucleic acid according to embodiment 16. A host cell comprising a nucleic acid according to embodiment 16 or a vector according to embodiment 17. A fusion protein comprising a human p75NTR extracellular domain, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134, and a half-life extending moiety. The fusion protein according to embodiment 19 wherein the half-life extending moiety is selected from an Fc domain, a serum albumin binder or PEG. The fusion protein according to embodiment 19 wherein the half-life extending moiety is a wild type or mutant Fc domain. The fusion protein according to any of embodiments 19 to 21 wherein the half-life extending moiety is an Fc domain and the p75NTR extracellular domain or portion thereof and the Fc domain are linked with a linker. The fusion protein according to embodiment 22 wherein the linker is a peptide linker. The fusion protein according to embodiment 23 wherein the peptide linker is (G4S)n wherein n is 1 to 4. The fusion protein according to any of embodiments 19 to 24 wherein the Fc domain is a human Fc domain. The fusion protein according to embodiment 25 wherein the fusion protein comprises or consists of a sequence selected from SEQ ID NO: 85, SEQ ID NO: 88, SEQ ID NO: 91, SEQ ID NO: 94 or SEQ ID NO: 97. A nucleic acid encoding a fusion protein according to any of embodiments 19 to 26. A vector comprising a nucleic acid according to embodiment 27. A host cell comprising a nucleic acid according to embodiment 27 or a vector according to embodiment 28. A pharmaceutical composition comprising an isolated polypeptide according to any of embodiments 1 to 15, or a fusion protein according to any of embodiments 19 to 26. A method for treating an NGF-related disorder in a subject comprising administering a human p75NTR protein according to any of embodiments 1 to 15, a fusion protein according to any of embodiments 19 to 26 or a pharmaceutical composition of embodiment 30. The use of an isolated human p75NTR protein according to any of embodiments 1 to 15, a fusion protein according to any of embodiments 19 to 26 or a pharmaceutical composition of embodiment 30 in the manufacture of a medicament for the treatment of an NGF-related disorder in a subject The isolated human p75NTR protein according to any of embodiments 1 to 15, a fusion protein according to any of embodiments 19 to 26 or a pharmaceutical composition of embodiment 30, for use in the treatment of an NGF-related disorder in a subject. The method of embodiment 31 or the use of embodiment 32 wherein the NGF-related disorder is cardiovascular diseases, atherosclerosis, obesity, type 2 diabetes, metabolic syndrome, pain and inflammation. The method or use of embodiment 33 wherein the NGF-related disorder is a pain related disorder. The method or use of embodiment 34 wherein pain is selected from osteoarthritis pain, rheumatoid arthritis pain, surgical and postsurgical pain, incisional pain, general inflammatory pain, cancer pain, pain from trauma, neuropathic pain, neuralgia, diabetic neuropathy pain, pain associated with rheumatic diseases, pain associated with musculoskeletal diseases, visceral pain, and gastrointestinal pain. A method of inhibiting NGF activity in a subject comprising administering an isolated human p75NTR protein according to any of embodiments 1 to 15, a fusion protein according to any of embodiments 19 to 26 or a pharmaceutical composition of embodiment 30. The method or use of embodiment 34 or embodiment 35 or the method of embodiment 36 comprising administration of a second compound that treats pain. A kit comprising an isolated human p75NTR protein according to any of embodiments 1 to 15, a fusion protein according to any of embodiments 19 to 26 or a pharmaceutical composition of embodiment 30 and optionally instructions for use. A method for treating osteoarthritis in a human comprising administering an effective amount of an isolated human p75NTR protein or a portion thereof, or a pharmaceutical composition comprising said isolated human p75NTR protein or a portion thereof. The use of an isolated human p75NTR protein or a portion thereof, or a pharmaceutical composition comprising said isolated human p75NTR protein or a portion thereof for the manufacture of a medicament for in the treatment of osteoarthritis in a human. An isolated human p75NTR protein or a portion thereof, or a pharmaceutical composition comprising said isolated human p75NTR protein or a portion thereof for use in the treatment of osteoarthritis in a human. The method of embodiment 39, the use of embodiment 40, or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 41, wherein the isolated human p75NTR protein or a portion thereof comprises SEQ ID NO: 71. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 39 to 42 wherein the p75NTR protein or a portion thereof comprises the extracellular domain or part thereof. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use for use according to embodiment 43 wherein the p75NTR extracellular domain comprises SEQ ID NO: 73. The method, use, or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 39 to 44, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 45, wherein the variant amino acid at position 75 of p75NTR comprises a polar side chain. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 45 to 46, wherein the variant amino acid at position 75 of p75NTR is selected from serine, threonine, tyrosine, tryptophan, asparagine, glutamine or cysteine, preferably threonine. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 45 to 47, wherein the variant amino acid at position 109 of p75NTR comprises an aromatic side chain. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 45 to 48, wherein the variant amino acid at position 109 of p75NTR is selected from histidine, tyrosine, phenylalanine, or tryptophan. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 45 to 49, wherein the variant amino acid at position 133 of p75NTR comprises a charged side chain. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 45 to 50, wherein the variant amino acid at position 133 of p75NTR is selected from arginine, histidine, lysine, aspartic acid, or glutamic acid. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 45 to 51, wherein the variant amino acid at position 133 of p75NTR comprises a negatively charged side chain. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 52, wherein the variant amino acid at position 133 of p75NTR is selected from arginine, histidine, or lysine, preferably arginine. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 45 to 53, wherein the variant amino acid at position 134 of p75NTR comprises a hydrophobic side chain. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 45 to 54, wherein the variant amino acid at position 134 of p75NTR is selected from alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine, or tryptophan. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 45 to 55, wherein the variant amino acid at position 134 of p75NTR comprises a non-aromatic hydrophobic side chain. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 56, wherein the variant amino acid at position 134 of p75NTR is selected from alanine, valine, isoleucine, leucine, or methionine, preferably leucine. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 45 to 57, wherein the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 84, SEQ ID NO: 87, SEQ ID NO: 90, SEQ ID NO: 93 or SEQ ID NO: 96. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 45 to 58 wherein the p75NTR extracellular domain is truncated. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 39 to 59 wherein the isolated human p75NTR protein is provided as a fusion protein comprising said isolated human p75NTR extracellular domain or portion thereof and a half-life extending moiety. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 60, wherein the half-life extending moiety is selected from an Fc domain, a serum albumin binder or PEG. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 61, wherein the half-life extending moiety is a wild type or mutant Fc domain. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any of embodiments 60 to 62, wherein the half-life extending moiety is an Fc domain and the p75NTR extracellular domain or portion thereof and the Fc domain are linked with a linker. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 63, wherein the linker is a peptide linker. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition according to embodiment 64, wherein the peptide linker is (GGGG)n or (G4S)n wherein n is 1 to 4. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition according to embodiments 60 to 65, wherein the fusion protein comprises one of SEQ ID NO:81, SEQ ID NO:82, SEQ ID NO:83, SEQ ID NO:85, SEQ ID NO:88, SEQ ID NO:91, SEQ ID NO:94, SEQ ID NO: 97. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any one of embodiments 39 to 66 wherein said treatment of osteoarthritis comprises slowing or arresting of disease progression, reversal of disease progression, regrowth of cartilage and/or curative treatment. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 67 wherein said treatment is determined by the rate of cartilage loss or regrowth. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any one of embodiments 39 to 68 wherein said treatment of osteoarthritis further comprises the treatment of one or more NGF-related disorders in a human. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 69 wherein the one or more NGF-related disorders are cardiovascular diseases, atherosclerosis, obesity, type 2 diabetes, metabolic syndrome, pain and inflammation. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 70 wherein the NGF-related disorder is a pain related disorder. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 71 wherein pain is selected from osteoarthritis pain, rheumatoid arthritis pain, surgical and postsurgical pain, incisional pain, general inflammatory pain, cancer pain, pain from trauma, neuropathic pain, neuralgia, diabetic neuropathy pain, pain associated with rheumatic diseases, pain associated with musculoskeletal diseases, visceral pain, and gastrointestinal pain. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 70 wherein the NGF-related disorder is inflammation, wherein the inflammation is an inflammatory disease, condition, or symptom. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to embodiment 73 wherein the inflammatory disease, condition, or symptom is selected from the group consisting of single or multiple organ failure or dysfunction, sepsis, cytokine storm, fever, neurological dysfunction or impairment, loss of taste or smell, cardiac dysfunction, pulmonary dysfunction, liver dysfunction, acute or chronic respiratory dysfunction, graft versus host disease (GVHD), cardiomyopathy, vasculitis, fibrosis, ophthalmic inflammation, dermatologic inflammation, gastrointestinal inflammation, tendinopathies, allergy, asthma, glomerulonephritis, pancreatitis, hepatitis, non-alcoholic steatohepatitis (NASH), inflammatory arthritis, gout, multiple sclerosis, psoriasis, acute respiratory distress syndrome (ARDS), diabetic ulcers, non-healing wounds, lupus, autoimmune diseases associated with acute or chronic inflammation, and acute or chronic inflammation associated with viral, bacterial or fungal infection, swelling, tenderness, joint stiffness or decrease in joint mobility. 75. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any one of embodiment 39 to 74, wherein said treatment comprises prophylactic treatment. The method, use or the isolated human p75NTR protein or a portion thereof or the pharmaceutical composition for use according to any one of embodiments 39 to 75, comprising administration of a second compound. The invention is further described in the non-limiting examples. Examples Example 1 - Structural analyses of p75NTR-NGF interaction. [0201] A model of p75NTR extracellular domain as well as NGF was generated using alpha fold server (human crystal structure used as template – pdb code 3BUK) (Figure 2). Interacting residues between p75NTR and NGF were identified using distance and geometry cut- off. Mutations to improve/reduce binding as well as improve expression were identified. [0202] Figure 1 demonstrates alignment of canine, feline, bovine and equine p75NTR sequences which show high sequence identity between said species. [0203] Canine vs Feline: 1/164 (more than 99% identical) [0204] Canine vs Equine: 4/164 (97.6% identical) [0205] Feline vs Equine: 5/164 (97% identical) [0206] Canine vs Bovine: 2/164 (98.8% identical) Example 2 - Protein constructs and CHO-s transfection/expression [0207] The amino acid sequences for PetML119 variants are given in the Sequences section below. [0208] For protein production, DNA constructs were generated to encode chimeric Fc fusion protein comprising selected canine IgG constant regions (between hinge and C-terminus) fused to the extracellular domain of canine p75 lacking predicted O-glycosylation and γ-secretase sites. [0209] Both the canine IgG-B Fc domain and the p75 extracellular domain (res 31- 194 from UniProtKB - J9PAM0) were synthesised. Both genes were PCR amplified using Q5 high fidelity DNA polymerase (using specific primers including overlapping regions to allow assembly) and assembled into mammalian expression vector PetML119var using NEBuilder HIFI DNA Assembly (New England Biolabs). In the expression vector, the fusion protein chain and the antibiotic resistant gene expression units are flanked by DNA transposon piggyBac terminal inverted repeats to mediate stable integration into host cells in the presence of piggyBac transposase. The expression vector was then transfected into a suitable mammalian cell line such as CHO cells together with PiggyBac transposase to obtain stable expression. For fusion protein production, 1 × 10⁶/mL selected CHO cells are seeded in 800mL culture media (F17 + 4mM l-Gln + 0.3%P188 + 1:500 ACA) and incubated at 32^oC, 8% CO₂ with shaking at 130 rpm.2 % HyClone Cell Boost 7a supplement + 0.2 % HyClone Cell Boost 7b supplement 2mM glucose is added to the media daily from the 4^th day of overproduction. Culture supernatants are collected on day 10 and the protein concentration is determined using surface plasmon resonance using protein A chip (Biacore 8K, Cytiva Life Sciences). [0210] Typically, PetML119var showed peak of expression at 10day in production reaching between 20 to 150mg/L, with high affinity molecules (PetML119-S109Y, PetML119- S109H, PetML119-V133R) showing a 2x improvement in respect to WT molecule (SEQ ID NO:11), while lower affinity molecules (PetML119-E75T, PetML119-D134L) showed slightly lower titres. [0211] PetML119: 60mg/L [0212] PetML119-E75T: 20mg/L [0213] PetML119-S109Y: 130mg/L [0214] PetML119-S109H: 150mg/L [0215] PetML119-V133R: 120mg/L [0216] PetML119-D134L: 30mg/L Example 3 - PetML119var Purification [0217] Cell suspensions from PetML119var stable transfected clones, cultured as described for at least 7days, were filtered using 0.22um filters after being incubated for 10 minutes with Sartoclear Dynamics® Lab V (SDLV-0500-20C—E). Cleared supernatants were loaded into Mabselect sure LX prepacked 20mL column (17547402), pre-equilibrated with PBS. The column was washed with 40mLs of PBS (2CV) and then fusion proteins have been eluted using gradient (0-100% in 2CV) of 0.1M Glycine pH2.7. Fractions containing fusion proteins were pooled together and neutralised with 100mM TRIS pH8 (final concentration). [0218] Neutralised fusion protein pooled fractions were concentrated to 5mL and loaded into PBS pre-equilibrated HiLoad 16/600 Superdex 200 pg (28989335) as second step purification. Monomeric fractions (based on previously analysed protein standards’ retention times) were pooled and protein concentration was assessed using NanoDrop™ One (Thermo Scientific™). [0219] Around 10-60mg/L of purified product was obtained following the above mentioned protocol. Variants were purified to the same extent as WT; yield of the variants were not altered during the purification process relative to WT. [0220] PetML119: 30mg/L after 2 steps purification [0221] PetML119-E75T: 10mg/L after 2 steps purification [0222] PetML119-S109Y: 60mg/L after 2 steps purification [0223] PetML119-S109H: 63.3mg/L after 2 steps purification [0224] PetML119-V133R: 56.6mg/L after 2 steps purification [0225] PetML119-D134L: 13.3mg/L after 2 steps purification Example 4 - HPLC Analytical chromatography [0226] Purified material purity was assessed using both Size Exclusion Chromatography (SEC), for oligomerisation analyses, and cation exchange chromatography (SCX) for charge variants analyses. [0227] HPLC-SEC chromatography (column: BioResolve SEC mAb 200A, 2.5um column WATERS) was performed using ACQUITY H-class Bio from WATERS using PBS as mobile phase with isocratic 0.575mL/min flow rate. [0228] HPLC-SCX chromatography (column: BioResolve SCX mAb Column, 3 µm, 4.6 mm x 100 mm) was performed using ACQUITY H-class Bio from WATERS using MES pH5 as mobile phase with salt gradient used to separate charge variants at 0.9mL/min flow rate. [0229] 10uL of each sample was injected into both H-SEC and H-SCX using the above-mentioned protocol. Percentage of monomeric species and Area (indicative of protein concentration) were determined for each molecule. [0230] Both PetML119wt and var showed very high purity (more than 99%) by HSEC and few charge variants (potentially corresponding to different glycoforms) were observed by HSCX, confirming that variants of p75 do not impact final purity and homogeneity of the product. Example 5 - Protein A binding affinity validation [0231] Purified fusion proteins in PBS were concentrated using centrifugal concentrators (Sartorious - VS02H22) to 5mg/mL Protein concentration was assessed using UV absorbance at 280nm with NanoDrop™ One (Thermo Scientific™). [0232] Binding affinity of fusion proteins to Protein A was assessed using Biacore 8K (Cytiva). [0233] Briefly, Sensor Chip Protein A (Cytiva) was docked into Biacore 8K, equilibrated for 30’ at RT and then Running Buffer (10mM HEPES pH7.4150mM NaCl 3mM EDTA and 0.005% Tween20) was applied to the SPR chip surface. [0234] Fusion protein dilutions were prepared diluting PetML119var from 1uM to 4nM (6 concentrations with 1:3 dilutions) in Running Buffer and kinetics was assessed using single cycle kinetics method (Biacore Assay Handbook, Cytiva). Kinetics and/or Affinity quantification have been performed using Biacore Insight following standard analyses methods. [0235] The results show that none of p75NTR mutations induced changes in protA binding. Example 6 - Human and rat Nerve Growth Factor (h-rNGF) and other NTs binding affinity determination [0236] Purified fusion proteins in PBS were concentrated using centrifugal concentrators (Sartorious - VS02H22) to 5mg/mL Protein concentration was assessed using UV absorbance at 280nm with NanoDrop™ One (Thermo Scientific™). [0237] Binding affinity of fusion proteins to human and rat NGF was assessed using Biacore 8K (Cytiva). Briefly, Protein A Sensor Chip (Cytiva) was docked into Biacore 8K, equilibrated for 30’ at RT and then Running Buffer (10mM HEPES pH7.4150mM NaCl 3mM EDTA and 0.005% Tween20) was applied to the SPR chip surface. [0238] PetML119var was diluted into running buffer at 6nM concentration. These were immobilised using 90sec association at 10uL/min as capturing step, followed by injection of running buffer to remove any unbound product. [0239] Human NGF (from Bio-Techne Ltd - 556-NG/CF / 256-GF-100/CF), human BDNF (11166-BD), human NT-3 (267-N3-025/CF), human NT-4 (268-N4-025/CF) and proNGF (were diluted in Running Buffer at 100nM with 1:2 further dilutions down to 4.68nM. Kinetics were assessed using multi-cycle kinetics with capture step method (30sec association – 300sec dissociation) followed by regeneration step (0.1M Glycine pH2.2 contact time 60sec FR 30uL/min). Kinetics quantification have been performed using Biacore Insight following standard analyses methods. [0240] Results showed subnanomolar KD for both human NGF with PetML119wt improved variants (Figure 3 and Table 1). Lower affinity mutants to NGF showed 20x and 40x reduced affinity relative to that observed with PetML119wt. Both PetML119wt and variants displayed dissociation from NGF over time, indicating that the binding is reversible. This contrasts with that observed with anti-NGF mAb (Bedinvetmab) where the binding remained constant over time. Table 1 Binding affinity using hNGF Antibody/Fc-protein KD (nM) RMAX Anti-NGF mAb 0.0073 837.1 PetML119 0.309 116.7 PetML119-E75T 12.4 77.1 PetML119-S109Y 0.225 91.1 PetML119-S109H 0.267 111.6 PetML119-V133R 0.346 109.2 PetML119-D134L 6.8 80.9 Binding affinity using hBDNF Antibody/Fc-protein KD (nM) RMAX Anti-NGF mAb ND ND PetML119 14.4 32.4 PetML119-E75T 15.4 31.2 PetML119-S109Y 16.7 18.1 PetML119-S109H 16.2 17.5 PetML119-V133R 42.3 7.5 PetML119-D134L 26.7 6.5 Binding affinity using hNT-3 Antibody/Fc-protein KD (nM) RMAX Anti-NGF mAb ND ND PetML119 4.9 32.5 PetML119-E75T 5.1 38.8 PetML119-S109Y 8.3 40.1 PetML119-S109H 7.9 40.5 PetML119-V133R 7.2 35.7 PetML119-D134L 8.3 40.2 Binding affinity using hNT-4 Antibody/Fc-protein KD (nM) RMAX Anti-NGF mAb ND ND PetML119 7.2 8.2 PetML119-E75T 98.5 3.9 PetML119-S109Y 12.0 6.4 PetML119-S109H 9.1 6.3 PetML119-V133R 8.3 6.1 PetML119-D134L 101.1 3.1 Binding affinity using h-proNGF Antibody/Fc-protein KD (nM) RMAX Ant-NGF mAb 0.0018 186 PetML119 0.0019 259 The same molecules have been tested also for binding to other 3 neurotrophins (BDNF, NT-3 and NT-4) using the same approach. The results showed that rational mutations on p75NTR ECD selectively alter NGF binding with no impact on the other mature NTs (only NT-4 showed reduced binding affinities with E75T and D134L, possibly due to some local atomic similarities between these two NTs). PetML119 and Bedinvetmab binding affinity to proNGF have been tested using same approach to confirm that p75NTR-Fc was able to bind this form at higher affinity than the mature form: PetML119 showed 171x higher affinity towards the pro-peptide (0.0019 nM proNGF v 0.309 nM NGF). Bedinvetmab, an antibody raised against the mature NGF protein, showed similar results with both pro-NGF and mature NGF. Example 7 - Unfolding and oligomerisation determination [0241] Purified fusion proteins in PBS were concentrated using centrifugal concentrators (Sartorious - VS02H22) to 5mg/mL Protein concentration was assessed using UV absorbance at 280nm with NanoDrop™ One (Thermo Scientific™). [0242] Tm and Tagg analyses were performed on UnCle from Unchained labs using a standard protocol. [0243] Briefly, 10uL of fusion protein was used to determine unfolding and aggregation events during a temperature ramp (from 25°C till 95°C). [0244] As anticipated from previous results, PetML119 showed no aggregation up to 95°C with Tm1 around 78°C. Similarly, all mutants showed no aggregation up to 95°C with Tm1 around 76°C (Figure 4). Example 8 - In vitro NGF inhibition assay [0245] To assess biological activity of the p75 fusion protein, an NGF-dependent cell line was used. Proficient sequestration of NGF by our fusion protein will result in slower proliferation in comparison to control. [0246] TF-1 cell line was bought from ATCC (CRL-2003) and kept in culture using standard aseptic methods using complete RPMI (10% FBS + 2mM l-Gln + 10ng/mL hNGF). [0247] 2 million TF-1 cells were labelled with 2.5uM CFSE cell trace (Invitrogen - C34554) in 1mL of RPMI only for 30 minutes at RT in the dark. Cells were then washed 2x in complete RPMI media, counted again and seeded at 10000cells/mL (1mL total volume per well) in 24-well plate. [0248] Dilution of PetML119wt and variants or controls (Bedinvetmab – anti-NGF IgG control, RPMI without NGF as negative control) were diluted in 100uL of RPMI media from 3uM concentration till 91.25nM.100uL of protein dilution was added to each well. [0249] Plates were analysed after 3 days. Briefly, 1mL cell suspension was centrifuged for 5 minutes at 300g RT, washed 2 times with FACS buffer (PBS + 3% FBS + 3mM EDTA) and finally resuspended in 100uL of FACS buffer. Cells were acquired using CytoFLEX Flow Cytometer using following parameters (FSC:20 ; SSC:50 ; FITC:1 ; threshold: 1313131). Cells were gated based on FITC fluorescence (more fluorescence less proliferation) and % of proliferation inhibition was calculated considering 100% inhibition TF-1 cells cultured in RPMI without NGF and 0% inhibition cells cultured with complete RPMI media. Graph pad was used to calculate IC50 values. [0250] PetML119wt, variants and Bedinvetmab were able to inhibit TF-1 proliferation in a dose dependent manner (Figure 5, Table 2). Incubation with Bedinvetmab showed complete inhibition, whilst incubation with PetML119wt had an IC MAX around 60-70%. Lower affinity NGF binding molecules showed a reduced inhibition ability (particularly D134L mutant) relative to PetML119wt. High affinity NGF binding molecules showed an improved inhibition ability relative to PetML119wt, similar to Bedinvetmab. Importantly, the IC MAX of all variants did not reach 100, indicating partial inhibition. This contrasts with anti-NGF Bedinvetmab which shows an IC Max of 100, indicating complete inhibition. Table 2 PetML119 PetML119-E75T PetML119-D134L Bedinvetmab IC50 (nM) 4.455 18.16 328.8 0.8899 ICMAX (%) 73.1 72.51 70.54 96.83 PetML119 PetML119-S109Y PetML119-S109H PetML119-V133R IC50 (nM) 4.455 0.1701 2.146 5.061 ICMAX (%) 73.1 88.51 93.45 80.49 Example 9 - PathHunter® eXpress Receptor Tyrosine Kinase Functional Assay Kit [0251] To further prove that our molecules are able to inhibit NGF pathway activation in-vitro, the PathHunter® eXpress Receptor Tyrosine Kinase Functional Assay Kit was used. This included a cell line engineered to have TrkA intracellular domain fused with a small complementing fragment of β-Gal. [0252] The larger portion of β-gal, termed EA for ‘enzyme acceptor’, was fused to proteins containing phospho-tyrosine binding domains. Ligand-induced activation of the receptor causes either homo or hetero-dimerization of the receptor which results in cross-phosphorylation. The SH2-EA fusion protein then specifically binds the phosphorylated receptor resulting in complementation of the two fragments of β-gal and formation of a functional enzyme. β-gal activity is then quantitatively detected using the chemiluminescent substrate in the PathHunter Detection Kit. Briefly, 3uM concentration till 91.25nM of PetML119wt, var and positive control anti-NGF mAB (Bedinvetmab) was used while NGF was used at 2nM. [0253] Luminescence readings showed that, similarly to that seen in the TF-1 assay, anti-NGF mAb has a distinct sigmoidal shape inhibition curve reaching 100% TrkA inhibition (Figure 6). In contrast to anti-NGF but consistent with the TF-1 assay, PetML119 molecules showed shallower inhibition curve that did not reach 100% inhibition. Also, high affinity NGF PetML119 molecules showed increased max inhibition in comparison to WT (although still not reaching 100% inhibition) as well as reduced IC50, whilst lower affinity NGF PetML119 molecules showed reduced max inhibition in comparison to WT as well as increased IC50, again consistent with the TF-1 inhibition assay (Table 3). [0254] Altogether these results suggest that anti-NGF mAb Bedinvetmab differs from PetML119 molecules both on inhibition concentration and amplitude of inhibition. Our new molecules of rationally engineered PetML119 mutants can either approach Bedinvetmab level NGF inhibition or further reduce PetML119wt NGF inhibition. Importantly, this is achieved without achieving 100% inhibition of NGF, which provides a mechanistic basis behind its expected DMOAD activity in-vivo. Table 3 P_etML119 PetML119 PetML119- PetML119- PetML119 PetML119- -S109Y S109H V133R -E75T D134L Bedinvetmab _Best-fit Bottom (%) 9.5 7.794 10.35 14.33 44.45 53.68 5.352 Top (%) Unstable 87.3 48.3 49.29 72.63 82.73 123 IC50 (nM) 8.04 2.154 2.201 2.56 82.62 20.84 4.238 Example 10 - MIA-induced OA in rats (efficacy, pK and joint diameter measurements) [0255] Efficacy and half-life for PetML119 and variants were analysed using a rat model of OA. The detailed protocol is shown below. The model is shown in Figure 7. Induction of Arthritis [0256] Osteoarthritis was induced chemically by an intra-articular (I.A.) injection of 3 mg of monosodium-iodoacetate (MIA) (in 25 µL saline) into the right hind limb knee joint of the rat given under isoflurane anesthesia. While under anesthesia, ophthalmic ointment was applied to both eyes. The day of I.A. injection of MIA was counted as Day 0. Allocation to Treatment Groups [0257] Baseline dynamic weight bearing (DWB) were measured for all rats. Body weight (BW) was also measured at the same time. Rats were anesthetized and MIA injected into the right Knee joint through the middle of the patellar tendon approximately perpendicular to the tibia (Intra-articular (I.A.)). Dose level for I.A. injection of MIA was selected based on previous literature report in rodents (Bove et al.: Weight bearing as a measure of disease progression and efficacy of anti-inflammatory compounds in a model of monosodium iodoacetate-induced osteoarthritis. Osteoarthritis Cartilage.2003 Nov;11(11):821-830). Animals showing a significant weight bearing difference between the MIA injected limb (right) and the healthy limb (left) were assigned to the study. Randomization was done based on both baseline DWB and BW (two variables randomization). Dynamic Weight Bearing (DWB) Evaluation [0258] Dynamic Weight Bearing was evaluated using the BioSeb® automated DWB system according to the manufacturer’s manual. A two-minute recording was done for each rat. Analysis of dynamic weight bearing data was done off-line using the BioSeb® software. The system automatically calculated the weight borne by each limb and the tail. Body weight was measured for each rat immediately before the DWB for each time of testing. DWB measurement was done at different time points as per schedule in Study Design. Total distance travelled was also noted during DWB data analysis. Dosing with test items [0259] Group 1-2 rats received intravenous (IV) injections of vehicle and Group 3- 8 rats received IV injections with the test items at designated doses once on Day 3 as depicted in the table below. Monosodium-Iodoacetate (MIA)-Induced Rat Study Study design Table 4 *Gr Group Treatment TI Dose TI Route, TI Dosing level Volume schedule DWB testing N Day 3, Day 1 (baseline), 1 Naive/ Vehicle PBS 0 IV, 5mL/kg QD _{Days 3, 6, 14, 21} ¹⁰ 3mg M Day 3, Day 1 (baseline), 2 IA/ Vehicle PBS 0 IV, 5mL/kg QD _{Days 3, 6, 14, 21} ¹⁰ 3mg MIA/ Sampl 0.5 mg/kg Day 3, Day 1 (baseline), 3 e 1 (PetML119) IV, 5mL/kg QD _{Days 3, 6, 14, 21} ¹⁰ 3mg M 0.5 mg/kg Day 3, Day 1 (baseline), 4 IA/ Sample 2 (PetML119-E75T) IV, 5mL/kg QD _{Days 3, 6, 14, 21} ¹⁰ 3mg MIA/ Samp 0.5 mg/kg Day 3, Day 1 (baseline), 5 le 3 (PetML119-S109Y) IV, 5mL/kg QD _{Days 3, 6, 14, 21} ¹⁰ 3mg MIA/ Sampl Day 3, Day 1 (baseline), 6 e 1 (PetML119) 0.1 mg/kg IV, 5mL/kg QD _{Days 3, 6, 14, 21} ¹⁰ 3mg 0.1 mg/kg Day 3, Day 1 (baseline), 7 MIA/ Sample 2 (PetML119-E75T) IV, 5mL/kg QD _{Days 3, 6, 14, 21} ¹⁰ 3mg MIA Day 3, Day 1 (baseline), 8 / Sample 3 (PetML119-S109Y) 0.1 mg/kg IV, 5mL/kg QD _{Days 3, 6, 14, 21} ¹⁰ *Animals from Groups 2 to 8 plus spares receive a single intra-articular (IA) injection with MIA (3mg/25μL saline) and the day of MIA injection is considered as Day 0 (in the right knee joint). IV: Intravenous (tail vein); PO: oral gavage; QD-once daily [0260] Treated animals were observed for any clinical signs during the study. No adverse signs were observed. DWB was analyzed on Days 3, 6, 14 and 21. Joint diameter was measured using a caliper on the right knee joint (medio-laterally) on days 3, 6, 14 and 21. [0261] Briefly, PetML119, PetML119-S109Y and PetML119-E75T (single dose) were tested for their analgesic effect (Figure 11). All molecules tested showed a good analgesic effect, reaching their maximum effect at day 6. The analgesic effect was dose dependent. As expected, lower affinity p75NTR variant PetML119-E75T showed reduced efficacy in pain relief in the long term (i.e. from day 14 onwards) while WT and PetML119-S109Y were efficacious till the end of the study. Similarly, joint diameter measurements showed enlarged knees from day 3 till the end of the study (only in WT and S109Y, E75T only till day 6) groups in a dose dependent way (Figure 13). This is usually associated with increased inflammation. [0262] PK bleeds from 5 rats per group were taken using standard procedures on alternative days. Serum pk analysis [0263] Sandwich ELISA to quantify serum levels of our fusion protein were set up as follows: ^ 30uL of 2ug/mL of Capturing antibody (Mouse anti-canine p75 Ab --> MAB367-SP (Novus Bio)) diluted in PBS + 0.1M sodium bicarbonate were immobilised on half-area ELISA plates (MICROPLATE, 96 WELL, PS, HALF AREA, CLEAR, Item No.: 675061) overnight at 4°C. ^ Plates were washed 2x with 200uL blocking solution (PBS + 5%DNFM + 0.2% Tween20) and blocking have been performed with 150uL of blocking solution across all wells for 3hrs at RT. ^ Sera from different timepoints/groups of rat study were diluted 100x in blocking solution (2uL serum + 198uL blocking solution) and 30uL were added to relevant wells. Standards from PetML119 were prepared diluting fusion protein into rat serum from 100ug/mL till 1ng/mL with 1:5 dilutions. Standards were then diluted 100x in blocking solution and 30uL have been added to relevant wells. ^ Sera were incubated for 1hr at RT with 450rpm shaking. ^ Plates were washed 2x with 200uL blocking solution; detection antibody (SA5-10309 (ThermoFisher)) have been diluted 1:40000 in blocking solution and 30uL were added to each well and left 30’ at RT with 450rpm shaking. ^ Plates were washed 2x with 200uL blocking solution; developing HRP-conjugated antibody (A16035 (ThermoFisher)) were diluted 1:10000 in blocking solution and 30uL were added to each well and left 30’ at RT with 450rpm shaking. ^ Plates were washed 2x with 200uL blocking solution then 2x with 200uL of PBS + 0.2%Tween20 and finally 50uL of TMB (TMB Chromogen Solution (for ELISA) --> 002023) were added to each well. After 10’, when standard curve showed saturation in first two points, the reaction was stopped adding 50uL of 1M Sulphuric acid. ^ All wells were read with CLARIOstar Plus (BMG LABTECH) using endpoint Absorbance at 650nm and 450nm. Values were imported in Graph Pad and one-phase decay fitting have been applied to estimate half-life of these. [0264] PetML119var displayed a similar plasma halflife (Figure 12A, Table 5). Table 5 One PetML119 PetML119 PetML119- PetML119- PetML119- PetML119- phase HD LD E75T HD E75T LD S109Y HD S109Y LD decay (0.5mg/kg) (0.1mg/kg) (0.5mg/kg) (0.1mg/kg) (0.5mg/kg) (0.1mg/kg) Y0 (ng/ml) 3655 971.8 6722 1806 3366 788.2 Plateau (hours) 422 83.38 290.4 137.6 196.3 79.53 Half Life (hours) 60.8 65.34 61.94 50.63 42 53.81 R squared 0.9292 0.927 0.9362 0.9336 0.9269 0.9537 NGF is generally not detected (or at very low levels) in plasma. An NGF binding molecule (i.e., mAb or Fc-fusion protein) administered systemically would lead to increased plasma levels of NGF. Rats treated with PetML119-E75T experienced a quicker NGF peak (24 hours) than WT molecule PetML119 (144 hours). Conversely, rats treated with PetML119-S109Y experienced a delayed NGF peak (336 hours). In this study we have shown that upon induction of MIA and administration of our p75-Fc molecules NGF levels in plasma were detectable. In addition, p75NTR variants showed distinct peak levels of NGF correlating with their affinity to this molecule. This is in agreement with long lasting analgesic effects seen by PetML119 and PetML119-S109Y while loss of activity after 6 days of PetML119-E75T. The observed differences in NGF inhibition may drive the anti-inflammatory/DMOAD effects in-vivo, as observed in joint diameter measurements. [0265] The variant molecules are expected to show the same safety properties as shown in the canine in vivo studies previously. This is, for example, demonstrated in Example 12 of WO2023067358, where animals maintain normal body weight and haematological parameters and do not generate anti-Drug Antibodies after administration of fusion proteins. The maintenance of normal body weight after administration is, for example, also demonstrated in Example 11 of WO2023067358. This is in contrast to the administration of dexamethasone which decreased body weight over time. Example 11 – disease-modifying osteoarthritis drug (DMOAD) in rats [0266] A model for assessing therapeutic effect of p75NTR-Fc molecules in OA rats was optimised. Briefly, osteoarthritis was induced by injecting a low dose of MIA (0.3mg) in eitherright/left knee of a rat. After 4 weeks, when signs of arthritis were visible, animals were treated IV 2 times 14 days apart (day 28 and day 42) with p75NTR-Fc molecules (at 3 doses, 0.5mg/kg – 0.2mg/kg and 0.05mg/kg) or vehicle as control. Each individuals per group were then sacrificed on day 56; affected knees were subjected to IHC (H&E, Saffron-O staining) and scored for Structural changes, Clones formations, Loss of Chondrocytes, SOFG staining loss, Osteophyte and composite score (sum of all the previous) using Mankin scoring system for Tibia medial, Tibia lateral, Femour medial and Femour Lateral sites. Sera at different timepoints were collected to assess active compound, NGF and other biomarkers systemic levels. [0267] Results, shown in Figure 15, display a dose dependent effect of p75NTR- Fc, with the lowest concentration having the most profound DMOAD effect on all osteoarthritis phenotypes analysed. Example 12 – anti-inflammatory investigation of p75NTR-Fc molecules in DH82 cell line [0268] Pro-NGF and NGF have different activities in-vivo, with the former showing pro-inflammatory, catabolic and apoptotic effects while the latter having anti- inflammatory, anabolic and proliferative effects. To assess whether the preferential binding on proNGF (and with less extent to NGF) p75NTR-Fc molecules have an impact on inflammation, an in-vitro assay using DH82 cell line (canine macrophage like - CRL-3590 ™ATCC) has been setup. [0269] Briefly, cells have been seeded at 1million/mL density in 6well plate using EMEM + 15% Heat-Inactivated FBS and left for 16 hrs at 37°C 5% CO2 in static incubator. Either 100ng/mL of LPS, 2ng/mL of IL1β or media only have been added to cells to induce pro- inflammatory effect (or using as control). Two concentrations of PetML119 (625nM or 1nM) or media only have been added concomitantly to cells. After 24hrs, supernatants have been collected and used for pro-inflammatory cytokines quantification. [0270] TNFα and IL-6, together with NGF (detecting both pro-NGF and mature NGF) ELISA (ab193687, ab193760 from AbCam and CA6000 from R&D Systems) have been used following provider specification. [0271] Results shown that both LPS and IL1β induced secretion of pro- inflammatory cytokines as well as total NGF in comparison to control (Figure 14). Treatment with PetML119 showed suppression of total NGF levels (Figure 14) in a dose response manner. Interestingly, PetML119 had differential activity on TNFα and IL-6 depending on concentration used. At high concentration, PetML119 induced higher secretion of cytokines, while at low concentration showed reduced levels of them. [0272] This interesting finding correlates with the preferential binding of PetML119 towards proNGF in contrast to NGF: at high concentration, p75NTR-Fc molecule can reduce both pro-NGF and mature NGF, preventing the anti-inflammatory activity of the mature form. At low concentrations, PetML119 can preferentially block pro-NGF (due to lower affinity to mature NGF), thus reducing its pro-inflammatory effects while free mature NGF can act as anti- inflammatory thus showing reduced TNFα and IL-6. Similarly, lower affinity variant molecules are expected to preferentially block pro-NGF. Lower affinity variant molecules e.g. E75T, are expected to have an anti-inflammatory effect at higher concentrations. Example 13 – Human p75NTR ECD stalk modification - protein constructs and CHO-s transfection/expression [0273] The amino acid sequences for protein constructs are listed below. Amino acid sequences are provided in the Sequences section PetML 308- Human p75NTR ECD full stalk IgG1 (SEQ ID NO:81) PetML 309 - Human p75NTR ECD partial stalk IgG1 (SEQ ID NO:82) PetML 319 - Human p75NTR ECD no stalk (SEQ ID NO:83) [0274] For protein production, DNA constructs were generated to encode chimeric Fc fusion protein comprising selected human IgG constant regions (between hinge and C- terminus) fused to the extracellular domain of human p75 either containing (PetML308 – full stalk) or lacking predicted γ-secretase sites only (PetML309 – partial stalk) or lacking O-glycosylation and γ-secretase sites (PetML319 – no stalk). [0275] Both the human IgG1 Fc domain and the p75 extracellular domain (res 31- 194 from UniProtKB) were synthesised. Both genes were PCR amplified using Q5 high fidelity DNA polymerase (using specific primers including overlapping regions to allow assembly) and assembled into mammalian expression vector PetML319var using NEBuilder HIFI DNA Assembly (New England Biolabs). In the expression vector, the fusion protein chain and the antibiotic resistant gene expression units are flanked by DNA transposon piggyBac terminal inverted repeats to mediate stable integration into host cells in the presence of piggyBac transposase. The expression vector was then transfected into a suitable mammalian cell line such as CHO cells together with PiggyBac transposase to obtain stable expression. For fusion protein production, 1 × 10⁶/mL selected CHO cells are seeded in 800mL culture media (F17 + 4mM l-Gln + 0.3%P188 + 1:500 ACA) and incubated at 32^oC, 8% CO2 with shaking at 130 rpm.2 % HyClone Cell Boost 7a supplement + 0.2 % HyClone Cell Boost 7b supplement 2mM glucose is added to the media daily from the 4^th day of overproduction. Culture supernatants are collected on day 10 and the protein concentration is determined using surface plasmon resonance using protein A chip (Biacore 8K, Cytiva Life Sciences). [0276] Typically, human p75-Fc molecules showed peak of expression at 10day in production reaching between 20 to 60mg/L, with no stalk molecule showing best performances followed by partial stalk and full stalk. PetML308: 20mg/L PetML309: 30mg/L PetML319: 60mg/L Example 14 - Human p75-Fc molecules Purification [0277] Cell suspensions from PetML319, PetML308 or PetML309 stable transfected clones, cultured as described for at least 7days, were filtered using 0.22um filters after being incubated for 10 minutes with Sartoclear Dynamics® Lab V (SDLV-0500-20C—E). Cleared supernatants have been loaded into Mabselect sure LX prepacked 20mL column (17547402), pre-equilibrated with PBS. Column has been washed with 40mLs of PBS (2CV) and then fusion proteins have been eluted using gradient (0-100% in 2CV) of 0.1M Glycine pH2.7. Fractionations containing fusion proteins have been pooled together and neutralised with 100mM TRIS pH8 (final concentration). [0278] Neutralised fusion protein pooled fractions have been concentrated till 5mL and loaded into PBS pre-equilibrated HiLoad 16/600 Superdex 200 pg (28989335) as second step purification. Monomeric fractions (based on previously analysed protein standards’ retention times) were pooled and protein concentration was assessed using NanoDrop™ One (Thermo Scientific™). [0279] Around 10-30mg/L of purified product was obtained following the above mentioned protocol. No difference in terms of purification recovery between wt and variants have been reported, differences are due to different titers. PetML308: 10mg/L after 2 steps purification PetML309: 12mg/L after 2 steps purification PetML319: 30mg/L after 2 steps purification Example 15 - HPLC Analytical chromatography [0280] Purified material purity was assessed using both Size Exclusion Chromatography (SEC), for oligomerisation analyses, and cation exchange chromatography (SCX) for charge variants analyses. [0281] HPLC-SEC chromatography (column: BioResolve SEC mAb 200A, 2.5um column WATERS) was performed using ACQUITY H-class Bio from WATERS using PBS as mobile phase with isocratic 0.575mL/min flow rate. [0282] HPLC-SCX chromatography (column: BioResolve SCX mAb Column, 3 µm, 4.6 mm x 100 mm) was performed using ACQUITY H-class Bio from WATERS using MES pH5 as mobile phase with salt gradient used to separate charge variants at 0.9mL/min flow rate. [0283] 10uL of each sample has been injected into both H-SEC / H-SCX using the above-mentioned protocol. Percentage of monomeric species and Area (indicative of protein concentration) were determined for each molecule. [0284] PetML319 showed very high purity (more than 99%) by HSEC and few charge variants (potentially corresponding to different glycoforms) were observed by HSCX, while PetML309 and 308 showed presence of aggregates, leading to the idea that this stalk region can negatively affect developability of these molecules. Example 16 - Protein A binding affinity validation [0285] Purified fusion proteins in PBS were concentrated using centrifugal concentrators (Sartorious - VS02H22) to 5mg/mL Protein concentration was assessed using UV absorbance at 280nm with NanoDrop™ One (Thermo Scientific™). [0286] Binding affinity of fusion proteins to Protein A was assessed using Biacore 8K (Cytiva). [0287] Briefly, Sensor Chip Protein A (Cytiva) was docked into Biacore 8K, equilibrated for 30’ at RT and then Running Buffer (10mM HEPES pH7.4150mM NaCl 3mM EDTA and 0.005% Tween20) was applied to the SPR chip surface. [0288] Fusion protein dilutions were prepared diluting PetML319, PetML308 or PetML309from 1uM to 4nM (6 concentrations with 1:3 dilutions) in Running Buffer and kinetics was assessed using single cycle kinetics method (Biacore Assay Handbook, Cytiva). Kinetics and/or Affinity quantification have been performed using Biacore Insight following standard analyses methods. [0289] The results show that all molecules have proficient protein A binding. Example 17- Human and rat Nerve Growth Factor (h-rNGF) binding affinity determination [0290] Purified fusion proteins in PBS were concentrated using centrifugal concentrators (Sartorious - VS02H22) to 5mg/mL Protein concentration was assessed using UV absorbance at 280nm with NanoDrop™ One (Thermo Scientific™). [0291] Binding affinity of fusion proteins to human and rat NGF was assessed using Biacore 8K (Cytiva). [0292] Briefly, Protein A Sensor Chip (Cytiva) was docked into Biacore 8K, equilibrated for 30’ at RT and then Running Buffer (10mM HEPES pH7.4150mM NaCl 3mM EDTA and 0.005% Tween20) was applied to the SPR chip surface. [0293] PetML319, PetML308 or PetML309 was diluted into running buffer at 6nM concentration. These have been immobilised using 90sec association at 10uL/min as capturing step, followed by injection of running buffer to remove any unbound product. [0294] Human and rat NGF (from Bio-Techne Ltd - 556-NG/CF / 256-GF-100/CF) was diluted in Running Buffer at 100nM with 1:2 further dilutions down to 4.68nM. Kinetics were assessed using multi-cycle kinetics with capture step method (30sec association – 300sec dissociation) followed by regeneration step (0.1M Glycine pH2.2 contact time 60sec FR 30uL/min). Kinetics quantification have been performed using Biacore Insight following standard analyses methods (Table 6). Table 6 ECD stalk ligand ka Rmax variant (1/Ms) kd (1/s) KD (M) (RU) PetML308 hNGF 3.42E+02 1.94E-03 5.68E-06 15.9 PetML309 hNGF 1.11E+06 2.75E-02 2.48E-08 18.4 PetML319 hNGF 8.86E+06 6.59E-04 7.43E-11 76.1 [0295] Results showed subnanomolar KD for both human and rat NGF with PetML319, while slightly lower affinity for PetML309 and 308 respectively (Table 7). Table 7 Antibody/Fc- KD protein (nM) RMAX Anti-NGF mAb 0.0073 837.1 PetML319 0.358 370.8 PetML308 8.78 345.4 PetML309 2.31 131.9 PetML309 2.31 131.9 Example 18 - Unfolding and oligomerisation determination [0296] Purified fusion proteins in PBS were concentrated using centrifugal concentrators (Sartorious - VS02H22) to 3mg/mL Protein concentration was assessed using UV absorbance at 280nm with NanoDrop™ One (Thermo Scientific™). [0297] Tm and Tagg analyses have been performed on UnCle from Unchained labs using standard protocol. (FIG.9) [0298] Briefly, 10uL of fusion protein have been used to determine unfolding and aggregation events during a temperature ramp (from 25°C till 95°C). All molecules showed no aggregation up to 95°C with Tm1 around 76°C. (Table 8) Table 8 ECD stalk variant Tm (°C) PetML308 75.6 PetML309 73.6 PetML319 81.04 Example 19 - PathHunter® eXpress Receptor Tyrosine Kinase Functional Assay Kit [0299] To further prove that our molecules are able to inhibit NGF pathway activation in-vitro, the PathHunter eXpress assay was used where a cell line was engineered to have TrkA intracellular domain fused with a small complementing fragment of β-Gal. The larger portion of β-gal, termed EA for ‘enzyme acceptor’, is fused to proteins containing phospho- tyrosine binding domains. Ligand-induced activation of the receptor causes either homo or hetero- dimerization of the receptor which results in cross-phosphorylation. The SH2-EA fusion protein then specifically binds the phosphorylated receptor resulting in complementation of the two fragments of β-gal and formation of a functional enzyme. β-gal activity is then quantitatively detected using the chemiluminescent substrate in the PathHunter Detection Kit. [0300] Briefly, 3uM concentration till 91.25nM of PetML119wt, var and positive control anti-NGF mAB (Bedinvetmab) have been used while NGF was used at 2nM. Luminescence readings showed that, similarly to what have been seen in TF-1 assay, anti-NGF mAb has a distinct sigmoidal shape inhibition curve reaching 100% TrkA inhibition. In contrast to anti-NGF but consistently again with TF-1 assay, PetML119 molecules do not reach 100% inhibition. Also, high affinity NGF PetML119 molecules showed increased max inhibition (still not 100%) and reduced IC50, while lower affinity NGF PetML119 molecules showed very little inhibition, again consistently with TF-1 inhibition assay. [0301] Altogether these results suggest that anti-NGF mAb Bedinvetmab differs from human p75-Fc molecules both on inhibition concentration and amplitude of inhibition. Moreover, no stalk molecule showed better performances than partial and full stalk, probably due to reduced stability and binding capacity as described before. Table 9 Bedinvetmab PetML308 PetML309 PetML319 Best-fit values Bottom (%) 2.111 44.48 28.73 9.5 Top (%) 93.48 105.2 97.92 Unstable IC50 (nM) 1.138 282.1 18.70 8.04 Sequences Canine p75NTR protein (SEQ ID NO:1) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGRWITRSTPSE DSDSTAPSTEEPELPPDQEIIASTMADVVTTVMGSSQPVVTRGTADNLIPVYCSILAAVV VGLVAYIAFKRWNSCKQNKQGANSRPVNQTPPPEGEKLHSDSGISVDSQSLHDQQPHTQ TAAGQALKGDGGLYSSLPPAKREEVEKLLNGSAGDTWRHLAGELGYQPEHIDSFTHEA CPARALLASWAAQDSATLDALLAALRRIQRADIVESLCSESTATSPV ECD is underlined. Canine p75NTR nucleic acid sequence (SEQ ID NO:2) ATGGACGGGCCGCGCCTGCTGCTGCTGCTGCTGCTGCTCCTGGGGGTGTCCCTTGGA GGTGCCAAGGAGGCATGTCCCACTGGCCTGTACACCCACAGCGGCGAGTGCTGCAA AGCCTGCAATCTGGGTGAGGGGGTGGCCCAGCCTTGCGGAGCCAACCAGACCGTGT GTGAGCCCTGCCTGGACAGCGTGACCTTCTCGGACGTGGTGAGCGCCACCGAGCCG TGCAAGCCGTGCACCGAGTGCGTGGGGCTGCAGAGCATGTCGGCGCCGTGCGTGGA GGCGGACGACGCCGTGTGCCGCTGCGCCTACGGCTACTACCAGGACGAGACGACGG GCCGCTGCGAGGCGTGCCGCGTGTGCGAGGCGGGCTCGGGGCTCGTGTTCTCGTGCC AGGACAGGCAGAACACCGTGTGCGAGGAGTGTCCCGACGGCACGTACTCCGACGAG GCCAACCACGTGGACCCGTGCCTGCCCTGCACCGTGTGCGAGGACACCGAGCGCCA GCTGCGCGAGTGCACGCGCTGGGCCGACGCCGAGTGCGAGGAGATCCCTGGCCGTT GGATTACCCGGTCCACACCCTCAGAGGACTCGGACAGCACCGCCCCCAGCACAGAG GAGCCAGAGCTACCTCCAGATCAAGAAATCATAGCCAGCACCATGGCAGATGTGGT GACCACAGTGATGGGCAGCTCTCAGCCTGTAGTGACCCGAGGAACCGCTGACAACC TCATCCCTGTCTACTGCTCCATCCTGGCCGCCGTGGTTGTGGGCTTAGTGGCCTACAT TGCCTTCAAGAGGTGGAACAGCTGCAAGCAGAACAAGCAAGGAGCCAACAGCCGG CCCGTGAACCAGACGCCTCCGCCGGAGGGAGAAAAGCTCCACAGTGACAGTGGCAT CTCTGTGGACAGCCAGAGCCTGCATGACCAGCAGCCCCACACACAGACGGCCGCAG GCCAGGCCCTCAAGGGGGATGGAGGTCTCTACAGCAGCCTGCCACCAGCCAAGCGG GAGGAGGTGGAGAAGCTGCTCAATGGCTCTGCGGGGGACACCTGGCGGCACCTGGC AGGTGAGCTGGGCTACCAGCCTGAGCACATAGACTCCTTCACCCACGAGGCCTGCC CAGCCCGAGCCCTGCTTGCCAGCTGGGCCGCCCAGGACAGCGCGACGCTCGACGCC CTCCTGGCTGCTCTGCGCCGCATCCAGCGAGCCGACATCGTGGAGAGCCTGTGTAGC GAGTCCACGGCCACGTCTCCAGTGTGA Leader sequence is underlined. Feline p75NTR protein (SEQ ID NO:3) KEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGRWITRSTPSE GSDSTAPSTEEPEVPPEQDLIASTVADVVTTVMGSSQPVVTRGTADNLIPVYCSILAAVV VGLVAYIAFKRWNSCKQDKQGANSRPVNQTPPPEGEKLHSDSGISVDSQSLHDQQSHTQ TAAGQALKGDGGLYSSLPSAKREEVEKLLNGSAGDTWRHLAGELGYQPEHIDSFTREA CPARALLASWAAQDSATLDALLAALRRIQRADIVESLCSESTATSPV ECD is underlined. Feline p75NTR nucleic acid sequence (SEQ ID NO:4) ATGGACGGGCCGCGCCCGCTGCTGCTGCTGTTGCCGCTGCTCCTGGGGGTGTCCCTT GGAGGTGCCAAGGAGGCATGTCCCACGGGCCTGTTCACCCACAGCGGCGAGTGCTG TAAAGCCTGCAACCTGGGAGAGGGCGTAGCCCAGCCTTGCGGAGCCAACCAGACCG TGTGTGAGCCCTGCCTGGACAGCGTGACCTTCTCGGACGTGGTGAGCGCCACGGAG CCGTGCAAGCCGTGCACCGAGTGCGTGGGCCTGCAGAGCATGTCGGCGCCGTGCGT GGAGGCCGACGACGCCGTGTGTCGCTGCGCCTACGGCTACTACCAGGACGAGACGA CGGGCCGCTGCGAGGCGTGCCGCGTGTGCGAGGCGGGCTCCGGCCTGGTGTTCTCGT GCCAGGACCGGCAGAATACCGTGTGCGAGGAGTGTCCCGACGGCACGTACTCGGAC GAGGCCAACCACGTGGACCCGTGCCTGCCCTGCACCGTGTGCGAGGACACCGAGCG CCAGCTGCGCGAGTGCACGCGCTGGGCCGACGCCGAGTGCGAGGAGATCCCTGGCC GTTGGATTACTCGGTCTACACCTTCGGAGGGCTCGGACAGCACCGCCCCCAGCACGG AGGAGCCAGAGGTACCTCCAGAGCAAGACCTCATAGCCAGCACGGTGGCAGATGTG GTGACCACAGTGATGGGCAGCTCTCAGCCCGTAGTGACCCGAGGCACCGCCGACAA CCTCATCCCTGTCTATTGTTCCATCCTGGCCGCTGTGGTTGTGGGCCTGGTGGCCTAC ATTGCCTTCAAGAGGTGGAACAGCTGCAAACAGGACAAGCAAGGCGCCAACAGCCG GCCCGTGAACCAGACGCCCCCGCCCGAGGGAGAAAAGCTCCACAGTGACAGTGGCA TCTCTGTGGACAGCCAGAGCCTGCATGACCAGCAGTCCCACACGCAGACGGCCGCC GGCCAGGCCCTCAAGGGGGACGGAGGTCTCTACAGCAGCCTGCCGTCAGCCAAGCG GGAGGAGGTAGAGAAACTGCTCAACGGCTCTGCGGGGGACACGTGGCGGCACCTGG CGGGCGAGCTGGGCTACCAGCCTGAGCACATAGACTCCTTCACCCGCGAGGCCTGC CCAGCCCGGGCCCTGCTCGCCAGCTGGGCCGCCCAGGACAGCGCGACGCTCGACGC CCTCCTGGCCGCCCTGCGCCGCATCCAGCGGGCCGACATCGTCGAGAGCCTGTGCAG CGAGTCCACGGCCACGTCCCCGGTGTGA Leader sequence is underlined. Equine p75NTR protein (SEQ ID NO:5) KEVCPTDLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACQVCEAGSGLVFSCQDKQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPSRWITRATPPE GSDSTAPSTQEPEGPPEKDLVASTVADVVTTVMGSSQPVVTRGTTDNLIPVYCSILAAVV VGLVAYIAFKRWNSCKQNKQGANSRPVNQTPPPEGEKLHSDSGISVDSQSLHDQQPHTQ TAAGQALKGDGGLYSSLPLAKREEVEKLLNGSAGDTWRHLAGLVGQGLLRLELVSVFQ GPAHGGMLPPATPSLQAPVWLGPEGCSEKWDQRGNAARRAGLRVWPMEGLSQV ECD is underlined. Equine p75NTR nucleic acid sequence (SEQ ID NO:6) ATGAGGGCAGGTGCCGCCGACTGCGCCATGGACGGACCGCGCCTTCTGCTGCTGCTT CTGCTCTTGGGGGTGTGCCTGCTGGGAGGTGCCAAGGAGGTGTGCCCCACAGACCTG TACACCCACAGCGGCGAGTGCTGCAAAGCCTGCAACCTGGGCGAGGGTGTGGCCCA GCCTTGCGGAGCCAACCAGACTGTGTGTGAACCCTGCCTGGACAGCGTGACGTTCTC GGACGTGGTGAGCGCCACAGAGCCATGTAAGCCGTGCACCGAGTGCGTGGGCCTGC AGAGCATGTCGGCGCCATGCGTGGAGGCCGACGACGCGGTGTGCCGCTGCGCCTAT GGCTACTACCAGGACGAGACGACGGGCCGCTGCGAGGCGTGCCAGGTGTGCGAGGC GGGCTCGGGCCTCGTGTTCTCGTGCCAGGACAAGCAGAACACCGTGTGCGAGGAAT GCCCCGACGGCACGTACTCCGACGAGGCCAACCACGTGGACCCGTGCCTGCCCTGC ACCGTGTGCGAGGACACCGAGCGCCAGCTGCGAGAGTGCACGCGCTGGGCCGACGC CGAGTGCGAGGAGATCCCCAGCCGTTGGATTACACGGGCCACGCCGCCGGAGGGCT CAGACAGCACTGCCCCCAGCACCCAGGAGCCCGAGGGACCTCCAGAGAAAGACCTT GTAGCCAGCACGGTGGCGGATGTGGTGACCACAGTGATGGGCAGCTCTCAGCCCGT GGTGACCCGAGGCACCACGGACAACCTCATCCCCGTCTATTGCTCCATCCTGGCCGC TGTGGTTGTGGGCCTTGTGGCCTACATCGCCTTCAAGAGGTGGAACAGCTGCAAGCA GAACAAGCAAGGAGCCAACAGCCGACCCGTGAACCAGACACCACCACCCGAGGGA GAAAAACTCCACAGCGACAGCGGCATCTCTGTGGACAGCCAGAGCCTGCATGACCA GCAGCCTCACACACAGACAGCCGCAGGCCAGGCCCTCAAGGGAGATGGAGGCCTCT ACAGCAGCCTGCCACTGGCCAAGAGGGAAGAGGTGGAGAAGCTACTCAATGGCTCC GCAGGGGACACCTGGCGGCACCTGGCGGGTGAGCTGGGCTACCAGCCCGAGCACAT AGACTCCTTCACCCACGAGGCCTGCCCCGTCCGCGCCCTGCTTGCCAGCTGGGCCGC CCAGGACAGTGCGACATTCGATGCCCTCCTGACCGCCCTGCGCCGCATCCAGCGAGC CGACATTGTCGAGAGCCTGTGCAGCGAGTCCACCGCCACATCCCCGGTGTGA Leader sequence is underlined. Canine p75NTR protein ECD (SEQ ID NO:7) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGRWITRSTPSE DSDSTAPSTEEPELPPDQEIIASTMADVVTTVMGSSQPVVTRGTADN The wt ECD region includes the stalk region (underlined) and alpha and gamma secretase cleavage 3’ of the stalk region (in bold) Canine p75NTR ECD nucleic acid sequence (SEQ ID NO:8) AAGGAGGCATGTCCCACTGGCCTGTACACCCACAGCGGCGAGTGCTGCAAAGCCTG CAATCTGGGTGAGGGGGTGGCCCAGCCTTGCGGAGCCAACCAGACCGTGTGTGAGC CCTGCCTGGACAGCGTGACCTTCTCGGACGTGGTGAGCGCCACCGAGCCGTGCAAG CCGTGCACCGAGTGCGTGGGGCTGCAGAGCATGTCGGCGCCGTGCGTGGAGGCGGA CGACGCCGTGTGCCGCTGCGCCTACGGCTACTACCAGGACGAGACGACGGGCCGCT GCGAGGCGTGCCGCGTGTGCGAGGCGGGCTCGGGGCTCGTGTTCTCGTGCCAGGAC AGGCAGAACACCGTGTGCGAGGAGTGTCCCGACGGCACGTACTCCGACGAGGCCAA CCACGTGGACCCGTGCCTGCCCTGCACCGTGTGCGAGGACACCGAGCGCCAGCTGC GCGAGTGCACGCGCTGGGCCGACGCCGAGTGCGAGGAGATCCCTGGCCGTTGGATT ACCCGGTCCACACCCTCAGAGGACTCGGACAGCACCGCCCCCAGCACAGAGGAGCC AGAGCTACCTCCAGATCAAGAAATCATAGCCAGCACCATGGCAGATGTGGTGACCA CAGTGATGGGCAGCTCTCAGCCTGTAGTGACCCGAGGAACCGCTGACAAC Canine ECD of p75NTR stalk region protein (SEQ ID NO:9) WITRSTPSEDSDSTAPSTEEPELPPDQEIIASTMADVVTTVM Canine ECD of p75NTR stalk region nucleic acid sequence (SEQ ID NO:10) TGGATTACCCGGTCCACACCCTCAGAGGACTCGGACAGCACCGCCCCCAGCACAGA GGAGCCAGAGCTACCTCCAGATCAAGAAATCATAGCCAGCACCATGGCAGATGTGG TGACCACAGTGATG Canine p75NTR ECD – canine IgGB wt Fc protein fusion (SEQ ID NO:11) MEWSWVFLFFLSVTTGVHSKEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPC LDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEAC RVCEAGSGLVFSCQDRQNTVCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRW ADAECEEIPGGGGRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTC VVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQF TCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVE WQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNHY TQKSLSHSPGK Signal peptide - Canine p75-ECD - Linker GGGG - Canine Fc-B-wt Canine p75NTR ECD – canine IgGB wt Fc nucleic acid sequence (SEQ ID NO:12) ATGGAATGGTCCTGGGTGTTCCTGTTCTTCCTGTCCGTGACCACCGGCGTGCACTCCA AAGAGGCTTGTCCTACCGGCCTGTACACCCACTCTGGCGAGTGTTGCAAGGCCTGTA ATCTCGGCGAAGGCGTGGCACAACCTTGTGGCGCTAATCAGACAGTGTGCGAGCCTT GCCTGGACTCCGTGACCTTCTCTGATGTGGTGTCTGCCACCGAGCCATGCAAGCCTT GTACCGAGTGTGTGGGCCTGCAGTCCATGTCTGCCCCTTGTGTGGAAGCCGACGACG CCGTGTGTAGATGTGCCTACGGCTACTACCAGGACGAGACAACCGGAAGATGCGAG GCCTGCAGAGTGTGTGAAGCTGGCTCTGGACTGGTGTTCTCCTGCCAAGACAGACAG AACACCGTGTGCGAGGAATGCCCTGACGGCACCTACTCTGATGAGGCCAATCACGT GGACCCCTGCCTGCCTTGTACTGTGTGCGAAGATACCGAGCGGCAGCTGCGCGAGT GTACCAGATGGGCTGATGCCGAGTGCGAAGAGATCCCTGGAGGTGGCGGACGCGAG AATGGCAGAGTGCCTAGACCTCCTGACTGCCCTAAGTGCCCTGCTCCTGAAATGCTC GGCGGACCCTCCGTGTTCATCTTCCCACCTAAGCCTAAGGACACCCTGCTGATCGCT CGGACCCCTGAAGTGACATGCGTGGTGGTGGATCTGGACCCCGAGGATCCTGAGGT GCAGATCAGTTGGTTCGTGGACGGCAAGCAGATGCAGACCGCTAAGACCCAGCCTA GAGAGGAACAGTTCAACGGCACCTACAGAGTGGTGTCTGTGCTGCCTATCGGCCAC CAGGATTGGCTGAAGGGCAAGCAGTTTACCTGCAAAGTGAACAACAAGGCCCTGCC TTCTCCAATCGAGCGGACCATCTCTAAGGCCAGAGGCCAGGCTCATCAGCCTTCCGT GTATGTCCTGCCACCTAGCCGCGAGGAACTGTCCAAGAACACCGTGTCTCTGACCTG CCTGATCAAGGACTTCTTCCCTCCTGACATCGACGTGGAATGGCAGTCCAACGGCCA GCAAGAGCCCGAGTCTAAGTACCGGACAACCCCTCCACAGCTGGACGAGGACGGCT CCTACTTCCTGTACTCCAAGCTGTCCGTGGACAAGTCTCGGTGGCAGAGAGGCGACA CCTTCATCTGTGCTGTGATGCACGAGGCCCTGCACAACCACTACACCCAGAAGTCCC TGTCTCACTCCCCTGGCAAGTGA Leader sequence is underlined. Canine p75NTR ECD – canine Fc YTE protein fusion (SEQ ID NO:13) MEWSWVFLFFLSVTTGVHSKEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPC LDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEAC RVCEAGSGLVFSCQDRQNTVCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRW ADAECEEIPGGGGRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLYITREPEVTC VVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQF TCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVE WQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNHY TQKSLSHSPGK Signal peptide - Canine p75-ECD - Linker GGGG - Canine Fc-B-YTE Canine p75NTR ECD - Fc YTE nucleic acid sequence (SEQ ID NO:14) ATGGAATGGTCCTGGGTGTTCCTGTTCTTCCTGTCCGTGACCACCGGCGTGCACTCCA AAGAGGCTTGTCCTACCGGCCTGTACACCCACTCTGGCGAGTGTTGCAAGGCCTGTA ATCTCGGCGAAGGCGTGGCACAACCTTGTGGCGCTAATCAGACAGTGTGCGAGCCTT GCCTGGACTCCGTGACCTTCTCTGATGTGGTGTCTGCCACCGAGCCATGCAAGCCTT GTACCGAGTGTGTGGGCCTGCAGTCCATGTCTGCCCCTTGTGTGGAAGCCGACGACG CCGTGTGTAGATGTGCCTACGGCTACTACCAGGACGAGACAACCGGAAGATGCGAG GCCTGCAGAGTGTGTGAAGCTGGCTCTGGACTGGTGTTCTCCTGCCAAGACAGACAG AACACCGTGTGCGAGGAATGCCCTGACGGCACCTACTCTGATGAGGCCAATCACGT GGACCCCTGCCTGCCTTGTACTGTGTGCGAAGATACCGAGCGGCAGCTGCGCGAGT GTACCAGATGGGCTGATGCCGAGTGCGAAGAGATCCCTGGAGGTGGCGGACGCGAG AATGGCAGAGTGCCTAGACCTCCTGACTGCCCTAAGTGCCCTGCTCCTGAAATGCTC GGCGGACCCTCCGTGTTCATCTTCCCACCTAAGCCTAAGGACACCCTGTATATCACT CGGGAACCTGAAGTGACATGCGTGGTGGTGGATCTGGACCCCGAGGATCCTGAGGT GCAGATCAGTTGGTTCGTGGACGGCAAGCAGATGCAGACCGCTAAGACCCAGCCTA GAGAGGAACAGTTCAACGGCACCTACAGAGTGGTGTCTGTGCTGCCTATCGGCCAC CAGGATTGGCTGAAGGGCAAGCAGTTTACCTGCAAAGTGAACAACAAGGCCCTGCC TTCTCCAATCGAGCGGACCATCTCTAAGGCCAGAGGCCAGGCTCATCAGCCTTCCGT CCTGATCAAGGACTTCTTCCCTCCTGACATCGACGTGGAATGGCAGTCCAACGGCCA GCAAGAGCCCGAGTCTAAGTACCGGACAACCCCTCCACAGCTGGACGAGGACGGCT CCTACTTCCTGTACTCCAAGCTGTCCGTGGACAAGTCTCGGTGGCAGAGAGGCGACA CCTTCATCTGTGCTGTGATGCACGAGGCCCTGCACAACCACTACACCCAGAAGTCCC TGTCTCACTCCCCTGGCAAGTGA Leader sequence is underlined. IgG-A (SEQ ID NO:15) MEFVLGWVFLVAILQGVQGEVQLVESGGDLVKPAGSLRLSCVASGFTFSNNAMNWVR QAPGKGLQWVAGINSGGSTASADAVKGRFTISRDNAKNTVYLQMNSLTAEDTAVYYC AKVIGNWIATSDLDYWGQGTLVIVSSASTTAPSVFPLAPSCGSTSGSTVALACLVSGYFP EPVTVSWNSGSLTSGVHTFPSVLQSSGLYSLSSMVTVPSSRWPSETFTCNVVHPASNTKV DKPVFNECRCTDTPPCPVPEPLGGPSVLIFPPKPKDILRITRTPEVTCVVLDLGREDPEVQI SWFVDGKEVHTAKTQSREQQFNGTYRVVSVLPIEHQDWLTGKEFKCRVNHIDLPSPIER TISKARGRAHKPSVYVLPPSPKELSSSDTVSITCLIKDFYPPDIDVEWQSNGQQEPERKHR MTPPQLDEDGSYFLYSKLSVDKSRWQQGDPFTCAVMHETLQNHYTDLSLSHSPGK IgG-B (SEQ ID NO:16) MEFVLGWVFLVAILQGVQGEVQLVESGGDLVKPAGSLRLSCVASGFTFSNNAMNWVR QAPGKGLQWVAGINSGGSTASADAVKGRFTISRDNAKNTVYLQMNSLTAEDTAVYYC AKVIGNWIATSDLDYWGQGTLVIVSSASTTAPSVFPLAPSCGSTSGSTVALACLVSGYFP EPVTVSWNSGSLTSGVHTFPSVLQSSGLYSLSSMVTVPSSRWPSETFTCNVAHPASKTKV DKPVPKRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDP EDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNN KALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQ QEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNHYTQKSLSH SPGK IgG-C (SEQ ID NO:17) MEFVLGWVFLVAILQGVQGEVQLVESGGDLVKPAGSLRLSCVASGFTFSNNAMNWVR QAPGKGLQWVAGINSGGSTASADAVKGRFTISRDNAKNTVYLQMNSLTAEDTAVYYC AKVIGNWIATSDLDYWGQGTLVIVSSASTTAPSVFPLAPSCGSQSGSTVALACLVSGYIP EPVTVSWNSGSLTSGVHTFPSILQSSGLYSLSSMVTVPSSRWPSETFTCNVAHPATNTKV DKPVVKECECKCNCNNCPCPGCGLLGGPSVFIFPPKPKDILVTARTPTVTCVVVDLDPEN PEVQISWFVDSKQVQTANTQPREEQSNGTYRVVSVLPIGHQDWLSGKQFKCKVNNKAL PSPIEEIISKTPGQAHQPNVYVLPPSRDEMSKNTVTLTCLVKDFFPPEIDVEWQSNGQQEP ESKYRMTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNHYTQKSLSHSP GK IgG-D (SEQ ID NO:18) MEFVLGWVFLVAILQGVQGEVQLVESGGDLVKPAGSLRLSCVASGFTFSNNAMNWVR QAPGKGLQWVAGINSGGSTASADAVKGRFTISRDNAKNTVYLQMNSLTAEDTAVYYC AKVIGNWIATSDLDYWGQGTLVIVSSASSTAPSVFPLAPSCGSTSGSTVALACLVSGYFP EPVTVSWNSGSLTSGVHTFPSVLKSSGLYSLSSMVTVPSSRLPSETFTCNVVHPATNTKV DKPVPKESTCKCISPCPVPESLGGPSVFIFPPKPKDILRITRTPEVTCVVLDLGREDPEVQIS WFVDGKEVHTAKTQPREQQFNSTYRVVSVLPIEHQDWLTGKEFKCRVNHIGLPSPIERTI SKARGQAHQPGVYVLPPSPKELSSSDTVTLTCLIKDFFPPEIDVEWQSNGQPEPESKYHT TAPQLDEDGSYFLYSKLSVDKSRWQQGDPFTCAVMHEALQNHYTDLSLSHSPGK DOGA constant region (SEQ ID NO:19) FNECRCTDTPPCPVPEPLGGPSVLIFPPKPKDILRITRTPEVTCVVLDLGREDPEVQISWFV DGKEVHTAKTQSREQQFNGTYRVVSVLPIEHQDWLTGKEFKCRVNHIDLPSPIERTISKA RGRAHKPSVYVLPPSPKELSSSDTVSITCLIKDFYPPDIDVEWQSNGQQEPERKHRMTPP QLDEDGSYFLYSKLSVDKSRWQQGDPFTCAVMHETLQNHYTDLSLSHSPGK DOGB constant region (SEQ ID NO:20) RENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEVTCVVVDLDPEDPEVQI SWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIE RTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKY RTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNHYTQKSLSHSPGK DOGB-YTE constant region (SEQ ID NO:21) RENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLYITREPEVTCVVVDLDPEDPEVQI SWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGKQFTCKVNNKALPSPIE RTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDVEWQSNGQQEPESKY RTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNHYTQKSLSHSPGK DOGC constant region (SEQ ID NO:22) ECECKCNCNNCPCPGCGLLGGPSVFIFPPKPKDILVTARTPTVTCVVVDLDPENPEVQIS WFVDSKQVQTANTQPREEQSNGTYRVVSVLPIGHQDWLSGKQFKCKVNNKALPSPIEEI ISKTPGQAHQPNVYVLPPSRDEMSKNTVTLTCLVKDFFPPEIDVEWQSNGQQEPESKYR MTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNHYTQKSLSHSPGK DOGD constant region (SEQ ID NO:23) ESTCKCISPCPVPESLGGPSVFIFPPKPKDILRITRTPEVTCVVLDLGREDPEVQISWFVDG KEVHTAKTQPREQQFNSTYRVVSVLPIEHQDWLTGKEFKCRVNHIGLPSPIERTISKARG QAHQPGVYVLPPSPKELSSSDTVTLTCLIKDFFPPEIDVEWQSNGQPEPESKYHTTAPQLD EDGSYFLYSKLSVDKSRWQQGDPFTCAVMHEALQNHYTDLSLSHSPGK CAT_IGG1V1 constant region (SEQ ID NO:24) TDHPPGPKPCDCPKCPPPEMLGGPSIFIFPPKPKDTLSISRTPEVTCLVVDLGPDDSDVQIT WFVDNTQVYTAKTSPREEQFNSTYRVVSVLPILHQDWLKGKEFKCKVNSKSLPSPIERTI SKAKGQPHEPQVYVLPPAQEELSRNKVSVTCLIKSFHPPDIAVEWEITGQPEPENNYRTT PPQLDSDGTYFVYSKLSVDRSHWQRGNTYTCSVSHEALHSHHTQKSLTQSPGK CAT_IGG1V2 constant region (SEQ ID NO:25) TDHPPGPKPCDCPKCPPPEMLGGPSIFIFPPKPKDTLSISRTPEVTCLVVDLGPDDSDVQIT WFVDNTQVYTAKTSPREEQFNSTYRVVSVLPILHQDWLKGKEFKCKVNSKSLPSPIERTI SKAKGQPHEPQVYVLPPAQEELSRNKVSVTCLIKSFHPPDIAVEWEITGQPEPENNYRTT PPQLDSDGTYFVYSKLSVDRSHWQRGNTYTCSVSHEALHSHHTQKSLTQSPGK CAT_IGG2 constant region (SEQ ID NO:26) KTASTIESKTGEGPKCPVPEIPGAPSVFIFPPKPKDTLSISRTPEVTCLVVDLGPDDSNVQIT WFVDNTEMHTAKTRPREEQFNSTYRVVSVLPILHQDWLKGKEFKCKVNSKSLPSAMER TISKAKGQPHEPQVYVLPPTQEELSENKVSVTCLIKGFHPPDIAVEWEITGQPEPENNYQT TPPQLDSDGTYFLYSRLSVDRSHWQRGNTYTCSVSHEALHSHHTQKSLTQSPGK HORSE_IGHG1 constant region (SEQ ID NO:27) VIKECNGGCPAECLQVGPSVFIFPPKPKDVLMISRTPTVTCVVVDVGHDFPDVQFNWYV DGVETHTATTEPKQEQFNSTYRVVSVLPIQHKDWLSGKEFKCKVNNKALPAPVERTISK PTGQPREPQVYVLAPHRDELSKNKVSVTCLVKDFYPTDIDIEWKSNGQPEPETKYSTTPA QLDSDGSYFLYSKLTVETNRWQQGTTFTCAVMHEALHNHYTEKSVSKSPGK HORSE_IGHG2 constant region (SEQ ID NO:28) CVLSAEGVIPIPSVPKPQCPPYTHSKFLGGPSVFIFPPNPKDALMISRTPVVTCVVVNLSDQ YPDVQFSWYVDNTEVHSAITKQREAQFNSTYRVVSVLPIQHQDWLSGKEFKCSVTNVG VPQPISRAISRGKGPSRVPQVYVLPPHPDELAKSKVSVTCLVKDFYPPDISVEWQSNRWP ELEGKYSTTPAQLDGDGSYFLYSKLSLETSRWQQVESFTCAVMHEALHNHFTKTDISES LGK HORSE_IGHG3 constant region (SEQ ID NO:29) TTPPCPCECPKCPAPELLGGPSVFIFPPKPKDVLMITRTPEVTCLVVDVSHDSSDVLFTWY VDGTEVKTAKTMPNEEQNNSTYRVVSVLRIQHQDWLNGKKFKCKVNNQALPAPVERTI SKATGQTRVPQVYVLAPHPDELSKNKVSVTCLVKDFLPTDITVEWQSNEHPEPEGKYRT TEAQKDSDGSYFLYSKLTVETDRWQQGTTFTCVVMHEALHNHVMQKNVSHSPGK HORSE_IGHG4 constant region (SEQ ID NO:30) VIKECNGGCPAECLQVGPSVFIFPPKPKDVLMISRTPTVTCVVVDVGHDFPDVQFNWYV DGVETHTATTEPKQEQFNSTYRVVSVLPIQHKDWLSGKEFKCKVNNKALPAPVERTISK PTGQPREPQVYVLAPHRDELSKNKVSVTCLVKDFYPTDIDIEWKSNGQPEPETKYSTTPA QLDSDGSYFLYSKLTVETNRWQQGTTFTCAVMHEALHNHYTEKSVSKSPGK HORSE_IGHG5 constant region (SEQ ID NO:31) VVKGSPCPKCPAPELPGGPSVFIFPPKPKDVLKISRKPEVTCVVVDLGHDDPDVQFTWFV DGVETHTATTEPKEEQFNSTYRVVSVLPIQHQDWLSGKEFKCSVTNKALPAPVERTTSK AKGQLRVPQVYVLAPHPDELAKNTVSVTCLVKDFYPPEIDVEWQSNEHPEPEGKYSTTP AQLNSDGSYFLYSKLSVETSRWKQGESFTCGVMHEAVENHYTQKNVSHSPGK HORSE_IGHG6 constant region (SEQ ID NO:32) KEPCCCPKCPGRPSVFIFPPNPKDTLMISRTPEVTCVVVDVSQENPDVKFNWYVDGVEA HTATTKAKEKQDNSTYRVVSVLPIQHQDWRRGKEFKCKVNNRALPAPVERTITKAKGE LQDPKVYILAPHREEVTKNTVSVTCLVKDFYPPDINVEWQSNEEPEPEVKYSTTPAQLD GDGSYFLYSKLTVETDRWEQGESFTCVVMHEAIRHTYRQKSITNFPGK HORSE_IGHG7 constant region (SEQ ID NO:33) VIKECGGCPTCPECLSVGPSVFIFPPKPKDVLMISRTPTVTCVVVDVGHDFPDVQFNWYV DGVETHTATTEPKQEQNNSTYRVVSILAIQHKDWLSGKEFKCKVNNQALPAPVQKTISK PTGQPREPQVYVLAPHRDELSKNKVSVTCLVKDFYPTDIDIEWKSNGQPEPETKYSTTPA QLDSDGSYFLYSKLTVETNRWQQGTTFTCAVMHEALHNHYTEKSVSKSPGK Portion of canine ECD (without stalk and without alpha and gamma secretase cleavage 3’ of the stalk region) that can be used in the fusion constructs with mutations described herein (SEQ ID NO:34) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIP Tandem repeat of portion of canine ECD (without stalk and without alpha and gamma secretase cleavage 3’ of the stalk region) that can be used in the fusion constructs with mutations described herein (SEQ ID NO:117) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPKEACPTGLYTH SGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCTECVGLQSMSAP CVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNTVCEECPDGTYS DEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIP Canine p75NTR ECD nucleic acid sequence as used in the fusion constructs (encoding only the first two stalk amino acids GR and without alpha and gamma secretase cleavage 3’ of the stalk region) (SEQ ID NO:35) AAGGAGGCATGTCCCACTGGCCTGTACACCCACAGCGGCGAGTGCTGCAAAGCCTG CCTGCCTGGACAGCGTGACCTTCTCGGACGTGGTGAGCGCCACCGAGCCGTGCAAG CCGTGCACCGAGTGCGTGGGGCTGCAGAGCATGTCGGCGCCGTGCGTGGAGGCGGA CGACGCCGTGTGCCGCTGCGCCTACGGCTACTACCAGGACGAGACGACGGGCCGCT GCGAGGCGTGCCGCGTGTGCGAGGCGGGCTCGGGGCTCGTGTTCTCGTGCCAGGAC AGGCAGAACACCGTGTGCGAGGAGTGTCCCGACGGCACGTACTCCGACGAGGCCAA CCACGTGGACCCGTGCCTGCCCTGCACCGTGTGCGAGGACACCGAGCGCCAGCTGC GCGAGTGCACGCGCTGGGCCGACGCCGAGTGCGAGGAGATCCCTGGCCGT Bovine p75 NTR protein (SEQ ID NO:36) KEACLTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDKQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGRWITRATPPE GSDSTDPSTQEPEVPPEQDLVTSTVSDVVTTVMGSSQPVVTRGTADNLIPVYCSILAAVV VGLVAYIAFKRWNSCKQNKQGANSRPVNQTPPPEGEKLHSDSGISVDSQSLHDQQPHTQ TAAGQALKGDGGLYSSLPLAKREEVEKLLNGSAGDTWRHLAGELGYQPEHIDSFTHEA CPARALLASWAAQDSATLDTLLAALRRIQRADLVESLCSESTATSPV ECD is underlined. Bovine p75 NTR nucleic acid (SEQ ID NO:37) ATGGGGTCAGGTGCCGCCGGCCGCGCCATGGACGGGCCGCGCCTGCTGCTGCTGCT GCTGCTGCTCCTGGGGGTGTCCCTTGGAGGTGCCAAGGAAGCATGCCTCACGGGCCT GTACACCCACAGCGGAGAGTGCTGCAAAGCCTGCAACCTGGGCGAGGGTGTGGCCC AGCCTTGTGGAGCCAACCAGACCGTGTGTGAACCCTGCCTGGACAGCGTGACCTTCT CGGACGTGGTGAGCGCCACGGAGCCGTGTAAGCCGTGCACGGAGTGCGTGGGACTG CAGAGCATGTCGGCGCCCTGCGTGGAGGCCGACGACGCCGTGTGCCGCTGCGCCTA CGGCTATTACCAGGACGAGACGACCGGCCGCTGCGAGGCGTGCCGCGTGTGCGAGG CGGGCTCGGGGCTCGTGTTCTCGTGCCAGGACAAGCAGAACACCGTCTGCGAGGAG TGCCCCGACGGCACGTACTCCGACGAGGCCAACCACGTGGACCCCTGCCTGCCCTGC ACGGTGTGCGAGGACACGGAGCGCCAGCTGCGCGAGTGCACGCGCTGGGCCGACGC CGAGTGCGAGGAGATCCCTGGACGTTGGATTACACGGGCCACGCCCCCTGAGGGCT CCGACAGCACAGACCCCAGCACCCAGGAGCCCGAGGTACCTCCAGAGCAAGATCTG GTAACCAGCACTGTGTCAGATGTGGTGACCACGGTGATGGGCAGCTCCCAGCCTGTG GTGACCCGAGGTACCGCCGACAACCTCATCCCTGTCTATTGCTCCATCCTGGCTGCT GTGGTTGTGGGCCTTGTGGCCTACATCGCCTTCAAGAGGTGGAACAGCTGCAAGCAG AACAAGCAAGGAGCCAACAGCCGACCTGTGAACCAGACACCCCCACCAGAGGGGG AAAAGCTACACAGCGATAGCGGCATCTCTGTGGACAGCCAGAGCCTGCATGACCAG CAGCCCCACACGCAGACTGCCGCAGGCCAGGCCCTCAAGGGTGATGGAGGCCTCTA CAGCAGCCTGCCGCTGGCCAAGCGGGAGGAGGTGGAGAAGCTGCTCAACGGCTCTG CGGGGGACACCTGGCGGCATCTGGCAGGCGAGTTGGGTTACCAGCCTGAGCACATA GACTCCTTCACCCACGAGGCCTGCCCAGCCCGCGCCCTGCTGGCCAGCTGGGCTGCC CAGGACAGCGCCACGCTCGACACCCTCCTTGCGGCCCTGCGCCGCATCCAGCGCGCC GACATCGTGGAGAGCCTGTGCAGCGAGTCCACGGCCACGTCCCCCGTGTGA Feline p75NTR protein ECD (SEQ ID NO:38) KEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGRWITRSTPSE GSDSTAPSTEEPEVPPEQDLIASTVADVVTTVMGSSQPVVTRGTADN Feline p75NTR ECD – feline IgG2 wt Fc protein fusion (SEQ ID NO:39) MDGPRPLLLLLPLLLGVSLGGAKEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVC EPCLDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRC EACRVCEAGSGLVFSCQDRQNTVCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECT RWADAECEEIPGRGGGGVPKTASTIESKTCDCPKCPVPEIPGAPSVFIFPPKPKDTLSISRT PEVTCLVVDLGPDDSNVQITWFVDNTEMHTAKTRPREEQFNSTYRVVSVLPILHQDWL KGKEFKCKVSKSLPSAMERTISKAKGQPHEPQVYVLPPTQEELSENKVSVTCLIKGFHPP DIAVEWEITGQPEPENNYQTTPPQLDSDGTYFLYSRLSVDRSHWQRGNTYTCSVSHEAL HSHHTQKSLTQSPGK Signal peptide - Feline p75-ECD - Linker GGGG - Feline Fc-IgG2 Feline p75NTR ECD– feline IgG2 wt Fc nucleic acid sequence (SEQ ID NO:40) ATGGATGGACCTAGACCTCTGCTGCTGCTCCTGCCTCTGCTGTTGGGAGTTTCTCTCG GCGGAGCCAAAGAGGCTTGTCCTACCGGCCTGTTTACCCACTCTGGCGAGTGTTGCA AGGCCTGTAATCTCGGCGAAGGCGTGGCACAACCTTGTGGCGCTAATCAGACAGTG TGCGAGCCTTGCCTGGACTCCGTGACCTTCTCTGATGTGGTGTCTGCCACCGAGCCA TGCAAGCCTTGTACCGAGTGTGTGGGCCTGCAGTCCATGTCTGCCCCTTGTGTGGAA GCCGACGACGCCGTGTGTAGATGTGCCTACGGCTACTACCAGGACGAGACAACCGG AAGATGCGAGGCCTGCAGAGTGTGTGAAGCTGGCTCTGGACTGGTGTTCTCCTGCCA AGACAGACAGAACACCGTGTGCGAGGAATGCCCTGACGGCACCTACTCTGATGAGG CCAATCACGTGGACCCCTGCCTGCCTTGTACTGTGTGCGAAGATACCGAGCGGCAGC TGCGCGAGTGTACCAGATGGGCTGATGCCGAGTGCGAAGAGATCCCTGGAAGAGGC GGAGGCGGAGTGCCTAAGACCGCTTCTACCATCGAGTCCAAGACCTGCGACTGCCC TAAGTGCCCTGTGCCTGAAATTCCTGGCGCTCCCTCCGTGTTCATCTTCCCACCTAAG CCTAAGGACACCCTGTCCATCTCTCGGACCCCTGAAGTGACCTGCCTGGTGGTTGAT CTGGGCCCTGACGACTCCAACGTGCAGATCACTTGGTTTGTGGACAACACCGAGATG CACACCGCCAAGACCAGACCTAGAGAGGAACAGTTCAACTCCACCTACAGAGTGGT GTCCGTGCTGCCCATCCTGCACCAGGATTGGCTGAAGGGCAAAGAATTCAAGTGCA AAGTGAACTCCAAGAGCCTGCCTTCCGCCATGGAACGGACCATCTCTAAGGCTAAG GGCCAGCCTCATGAGCCCCAGGTGTACGTTCTGCCTCCTACACAAGAGGAACTGTCC GAGAACAAAGTGTCCGTGACATGCCTGATCAAGGGCTTTCACCCTCCTGATATCGCC GTGGAATGGGAGATCACCGGACAGCCTGAGCCTGAGAACAACTACCAGACCACACC TCCTCAGCTGGACAGCGACGGAACCTACTTCCTGTACTCCCGGCTGTCCGTGGACAG ATCCCATTGGCAGAGAGGCAACACCTACACCTGTTCCGTGTCTCACGAGGCCCTGCA CTCTCATCACACCCAGAAGTCCCTGACACAGTCCCCTGGCAAG Feline IgG3 (SEQ ID NO:41) LPPCKCPKCPVPEIPGGPSVFIFPPKPKDTLSISRTPEVTCLVVDLGPDDSNVQITWFVDNT EMHTAKTRPREEQFNSTYRVVSVLPIVHQDWLTGKEFKCKVNSKALPSAIERTISKAKG QPHEPQVYVLPPAQEELSENKVCVTCLIKGFYPPDIAVEWEITGQPEPENNYRTTPPQLD SDGTYFVYSRLSMDRSRWQSGNTYTCSVSHEALHSHHTQKSLTQSPGK Feline p75NTR ECD – feline IgG1 wt Fc protein fusion (SEQ ID NO:42) MDGPRPLLLLLPLLLGVSLGGAKEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVC EPCLDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRC EACRVCEAGSGLVFSCQDRQNTVCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECT RWADAECEEIPGGGGVRKTDHPPGPKPCDCPKCPAPEMLGGPSIFIFPPKPKDTLSISRTP EVTCLVVDLGPDDSDVQITWFVDNTQVYTAKTSPREEQFNSTYRVVSVLPILHQDWLK GKEFKCKVNSKSLPSPIERTISKAKGQPHEPQVYVLPPAQEELSRNKVSVTCLIKSFHPPDI AVEWEITGQPEPENNYRTTPPQLDSDGTYFVYSKLSVDRSHWQRGNTYTCSVSHEALHS HHTQKSLTQSPGK Signal peptide - Feline p75-ECD - Linker GGGG - Feline Fc-IgG1 Feline p75NTR ECD – feline Ig1 wt Fc nucleic acid sequence (SEQ ID NO:43) ATGGATGGCCCTAGACCTCTGCTGCTGCTGTTGCCTCTGCTCCTGGGAGTTTCTCTCG GCGGAGCCAAAGAGGCTTGTCCTACCGGCCTGTTTACCCACTCTGGCGAGTGTTGCA AGGCCTGTAATCTCGGCGAAGGCGTGGCACAACCTTGTGGCGCTAATCAGACAGTG TGCGAGCCTTGCCTGGACTCCGTGACCTTCTCTGATGTGGTGTCTGCCACCGAGCCA TGCAAGCCTTGTACCGAGTGTGTGGGCCTGCAGTCCATGTCTGCCCCTTGTGTGGAA GCCGACGACGCCGTGTGTAGATGTGCCTACGGCTACTACCAGGACGAGACAACCGG AAGATGCGAGGCCTGCAGAGTGTGTGAAGCTGGCTCTGGACTGGTGTTCTCCTGCCA AGACAGACAGAACACCGTGTGCGAGGAATGCCCTGACGGCACCTACTCTGATGAGG CCAATCACGTGGACCCCTGCCTGCCTTGTACTGTGTGCGAAGATACCGAGCGGCAGC TGCGCGAGTGTACCAGATGGGCTGATGCCGAGTGCGAAGAGATTCCTGGCGGAGGC GGAGTGCGCAAGACAGATCATCCTCCTGGACCTAAGCCTTGCGACTGCCCTAAGTGT CCCGCTCCTGAAATGCTCGGCGGACCCAGCATCTTCATCTTCCCACCTAAGCCAAAG GACACCCTGTCCATCTCTCGGACCCCTGAAGTGACCTGCCTGGTGGTTGATCTGGGC CCTGACGATTCCGACGTGCAGATCACTTGGTTTGTGGACAACACCCAGGTGTACACA GCCAAGACCTCTCCAAGAGAGGAACAGTTCAACTCCACCTACAGAGTGGTGTCCGT GCTGCCCATCCTGCACCAGGATTGGCTGAAGGGCAAAGAATTCAAGTGCAAAGTGA ACTCCAAGAGCCTGCCTTCTCCAATCGAGCGGACCATCTCCAAGGCTAAGGGCCAG CCTCATGAGCCTCAGGTGTACGTTCTGCCTCCTGCTCAAGAGGAACTGTCCCGGAAC AAAGTGTCTGTGACCTGTCTGATCAAGAGCTTTCACCCTCCTGATATCGCCGTGGAA TGGGAGATCACCGGACAGCCTGAGCCTGAGAACAACTACCGGACCACACCTCCTCA GCTGGACAGCGACGGCACATACTTCGTGTACTCCAAGCTGTCCGTGGACAGATCCCA CTGGCAGCGGGGCAATACCTACACCTGTTCCGTGTCTCACGAGGCCCTGCACTCTCA TCACACCCAGAAGTCCCTGACACAGTCCCCTGGAAAGTGATGA Feline p75NTR ECD – feline IgG3 wt Fc protein fusion (SEQ ID NO:44) MDGPRPLLLLLPLLLGVSLGGAKEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVC EPCLDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRC EACRVCEAGSGLVFSCQDRQNTVCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECT RWADAECEEIPGGGGVLPPCKCPKCPVPEIPGGPSVFIFPPKPKDTLSISRTPEVTCLVVD LGPDDSNVQITWFVDNTEMHTAKTRPREEQFNSTYRVVSVLPIVHQDWLTGKEFKCKV NSKALPSAIERTISKAKGQPHEPQVYVLPPAQEELSENKVCVTCLIKGFYPPDIAVEWEIT GQPEPENNYRTTPPQLDSDGTYFVYSRLSMDRSRWQSGNTYTCSVSHEALHSHHTQKSL TQSPGK Signal peptide - Feline p75-ECD - Linker GGGG - Feline Fc-IgG3 Feline p75NTR ECD – feline IgG3 wt Fc nucleic acid sequence (SEQ ID NO:45) ATGGATGGCCCTAGACCTCTGCTGCTGCTGTTGCCTCTGCTCCTGGGAGTTTCTCTCG GCGGAGCCAAAGAGGCTTGTCCTACCGGCCTGTTTACCCACTCTGGCGAGTGTTGCA AGGCCTGTAATCTCGGCGAAGGCGTGGCACAACCTTGTGGCGCTAATCAGACAGTG TGCGAGCCTTGCCTGGACTCCGTGACCTTCTCTGATGTGGTGTCTGCCACCGAGCCA TGCAAGCCTTGTACCGAGTGTGTGGGCCTGCAGTCCATGTCTGCCCCTTGTGTGGAA GCCGACGACGCCGTGTGTAGATGTGCCTACGGCTACTACCAGGACGAGACAACCGG AAGATGCGAGGCCTGCAGAGTGTGTGAAGCTGGCTCTGGACTGGTGTTCTCCTGCCA AGACAGACAGAACACCGTGTGCGAGGAATGCCCTGACGGCACCTACTCTGATGAGG CCAATCACGTGGACCCCTGCCTGCCTTGTACTGTGTGCGAAGATACCGAGCGGCAGC TGCGCGAGTGTACCAGATGGGCTGATGCCGAGTGCGAAGAGATTCCTGGCGGAGGC GGAGTTCTGCCTCCTTGCAAGTGTCCTAAGTGCCCCGTGCCTGAAATCCCTGGCGGC CCTTCCGTGTTCATCTTCCCACCTAAGCCTAAGGACACCCTGTCCATCTCTCGGACCC CTGAAGTGACCTGCCTGGTGGTTGATCTGGGCCCTGACGACTCCAACGTGCAGATCA CTTGGTTTGTGGACAACACCGAGATGCACACCGCCAAGACCAGACCTAGAGAGGAA CAGTTCAACTCCACCTACAGAGTGGTGTCCGTGCTGCCCATCGTGCACCAGGATTGG CTGACCGGCAAAGAATTCAAGTGCAAAGTGAACAGCAAGGCCCTGCCTTCCGCCAT CGAGCGGACAATCTCTAAGGCTAAGGGCCAGCCTCACGAGCCCCAGGTTTACGTTTT GCCTCCTGCTCAAGAGGAACTGTCCGAGAACAAAGTGTGCGTGACCTGTCTGATCAA GGGCTTCTACCCTCCTGATATCGCCGTGGAATGGGAGATCACCGGACAGCCTGAGCC TGAGAACAACTACCGGACCACACCTCCTCAGCTGGATTCCGACGGCACATACTTCGT GTACTCCCGGCTGAGCATGGACAGATCCAGATGGCAGTCCGGCAACACCTACACCT GTTCCGTGTCTCACGAGGCCCTGCACTCTCATCACACCCAGAAGTCCCTGACACAGT CCCCTGGCAAG Variants Canine p75NTR ECD E75T (SEQ ID NO:46) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEATDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGR Canine p75NTR ECD E75T – canine IgGB wt Fc (SEQ ID NO:47) MEWSWVFLFFLSVTTGVHSKEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPC LDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEATDAVCRCAYGYYQDETTGRCEAC RVCEAGSGLVFSCQDRQNTVCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRW ADAECEEIPGRGGGGRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEV TCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGK QFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDV EWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNH YTQKSLSHSPGK Signal peptide - Canine p75-ECD - Linker GGGG - Canine Fc-B wt Canine p75NTR ECD E75T – canine IgGB wt Fc nucleic acid sequence (SEQ ID NO:48) ATGGAATGGAGCTGGGTGTTTCTGTTTTTTCTGAGCGTGACCACCGGCGTGCATAGC AAAGAAGCGTGCCCGACCGGCCTGTATACCCATAGCGGCGAATGCTGCAAAGCGTG CAACCTGGGCGAAGGCGTGGCGCAGCCGTGCGGCGCGAACCAGACCGTGTGCGAAC CGTGCCTGGATAGCGTGACCTTTAGCGATGTGGTGAGCGCGACCGAACCGTGCAAA CCGTGCACCGAATGCGTGGGCCTGCAGAGCATGAGCGCGCCGTGCGTGGAAGCGAC CGATGCGGTGTGCCGCTGCGCGTATGGCTATTATCAGGATGAAACCACCGGCCGCTG CGAAGCGTGCCGCGTGTGCGAAGCGGGCAGCGGCCTGGTGTTTAGCTGCCAGGATC GCCAGAACACCGTGTGCGAAGAATGCCCGGATGGCACCTATAGCGATGAAGCGAAC CATGTGGATCCGTGCCTGCCGTGCACCGTGTGCGAAGATACCGAACGCCAGCTGCG CGAATGCACCCGCTGGGCGGATGCGGAATGCGAAGAAATTCCGGGCCGCGGCGGCG GCGGCCGCGAAAACGGCCGCGTGCCGCGCCCGCCGGATTGCCCGAAATGCCCGGCG CCGGAAATGCTGGGCGGCCCGAGCGTGTTTATTTTTCCGCCGAAACCGAAAGATACC CTGCTGATTGCGCGCACCCCGGAAGTGACCTGCGTGGTGGTGGATCTGGATCCGGAA GATCCGGAAGTGCAGATTAGCTGGTTTGTGGATGGCAAACAGATGCAGACCGCGAA AACCCAGCCGCGCGAAGAACAGTTTAACGGCACCTATCGCGTGGTGAGCGTGCTGC CGATTGGCCATCAGGATTGGCTGAAAGGCAAACAGTTTACCTGCAAAGTGAACAAC AAAGCGCTGCCGAGCCCGATTGAACGCACCATTAGCAAAGCGCGCGGCCAGGCGCA TCAGCCGAGCGTGTATGTGCTGCCGCCGAGCCGCGAAGAACTGAGCAAAAACACCG TGAGCCTGACCTGCCTGATTAAAGATTTTTTTCCGCCGGATATTGATGTGGAATGGC AGAGCAACGGCCAGCAGGAACCGGAAAGCAAATATCGCACCACCCCGCCGCAGCT GGATGAAGATGGCAGCTATTTTCTGTATAGCAAACTGAGCGTGGATAAAAGCCGCT GGCAGCGCGGCGATACCTTTATTTGCGCGGTGATGCATGAAGCGCTGCATAACCATT ATACCCAGAAAAGCCTGAGCCATAGCCCGGGCAAA Canine p75NTR ECD S109Y (SEQ ID NO:49) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFYCQDRQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGR Canine p75NTR ECD S109Y – canine IgGB wt Fc (SEQ ID NO:50) MEWSWVFLFFLSVTTGVHSKEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPC LDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEAC RVCEAGSGLVFYCQDRQNTVCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRW ADAECEEIPGRGGGGRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEV TCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGK QFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDV EWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNH YTQKSLSHSPGK Signal peptide - Canine p75-ECD - Linker GGGG - Canine Fc-B wt Canine p75NTR ECD S109Y – canine IgGB wt Fc nucleic acid sequence (SEQ ID NO:51) ATGGAATGGAGCTGGGTGTTTCTGTTTTTTCTGAGCGTGACCACCGGCGTGCATAGC AAAGAAGCGTGCCCGACCGGCCTGTATACCCATAGCGGCGAATGCTGCAAAGCGTG CAACCTGGGCGAAGGCGTGGCGCAGCCGTGCGGCGCGAACCAGACCGTGTGCGAAC CGTGCCTGGATAGCGTGACCTTTAGCGATGTGGTGAGCGCGACCGAACCGTGCAAA CCGTGCACCGAATGCGTGGGCCTGCAGAGCATGAGCGCGCCGTGCGTGGAAGCGGA TGATGCGGTGTGCCGCTGCGCGTATGGCTATTATCAGGATGAAACCACCGGCCGCTG CGAAGCGTGCCGCGTGTGCGAAGCGGGCAGCGGCCTGGTGTTTTATTGCCAGGATC GCCAGAACACCGTGTGCGAAGAATGCCCGGATGGCACCTATAGCGATGAAGCGAAC CATGTGGATCCGTGCCTGCCGTGCACCGTGTGCGAAGATACCGAACGCCAGCTGCG CGAATGCACCCGCTGGGCGGATGCGGAATGCGAAGAAATTCCGGGCCGCGGCGGCG GCGGCCGCGAAAACGGCCGCGTGCCGCGCCCGCCGGATTGCCCGAAATGCCCGGCG CCGGAAATGCTGGGCGGCCCGAGCGTGTTTATTTTTCCGCCGAAACCGAAAGATACC CTGCTGATTGCGCGCACCCCGGAAGTGACCTGCGTGGTGGTGGATCTGGATCCGGAA GATCCGGAAGTGCAGATTAGCTGGTTTGTGGATGGCAAACAGATGCAGACCGCGAA AACCCAGCCGCGCGAAGAACAGTTTAACGGCACCTATCGCGTGGTGAGCGTGCTGC CGATTGGCCATCAGGATTGGCTGAAAGGCAAACAGTTTACCTGCAAAGTGAACAAC AAAGCGCTGCCGAGCCCGATTGAACGCACCATTAGCAAAGCGCGCGGCCAGGCGCA TCAGCCGAGCGTGTATGTGCTGCCGCCGAGCCGCGAAGAACTGAGCAAAAACACCG TGAGCCTGACCTGCCTGATTAAAGATTTTTTTCCGCCGGATATTGATGTGGAATGGC AGAGCAACGGCCAGCAGGAACCGGAAAGCAAATATCGCACCACCCCGCCGCAGCT GGATGAAGATGGCAGCTATTTTCTGTATAGCAAACTGAGCGTGGATAAAAGCCGCT GGCAGCGCGGCGATACCTTTATTTGCGCGGTGATGCATGAAGCGCTGCATAACCATT ATACCCAGAAAAGCCTGAGCCATAGCCCGGGCAAA Canine p75NTR ECD S109H (SEQ ID NO:52) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFHCQDRQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGR Canine p75NTR ECD S109H – canine IgGB wt Fc (SEQ ID NO:53) MEWSWVFLFFLSVTTGVHSKEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPC LDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEAC RVCEAGSGLVFHCQDRQNTVCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRW ADAECEEIPGRGGGGRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEV TCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGK QFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDV EWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNH YTQKSLSHSPGK Signal peptide - Canine p75-ECD - Linker GGGG - Canine Fc-B wt Canine p75NTR ECD S109H – canine IgGB wt Fc nucleic acid sequence (SEQ ID NO:54) ATGGAATGGAGCTGGGTGTTTCTGTTTTTTCTGAGCGTGACCACCGGCGTGCATAGC AAAGAAGCGTGCCCGACCGGCCTGTATACCCATAGCGGCGAATGCTGCAAAGCGTG CAACCTGGGCGAAGGCGTGGCGCAGCCGTGCGGCGCGAACCAGACCGTGTGCGAAC CGTGCCTGGATAGCGTGACCTTTAGCGATGTGGTGAGCGCGACCGAACCGTGCAAA CCGTGCACCGAATGCGTGGGCCTGCAGAGCATGAGCGCGCCGTGCGTGGAAGCGGA TGATGCGGTGTGCCGCTGCGCGTATGGCTATTATCAGGATGAAACCACCGGCCGCTG CGAAGCGTGCCGCGTGTGCGAAGCGGGCAGCGGCCTGGTGTTTCATTGCCAGGATC GCCAGAACACCGTGTGCGAAGAATGCCCGGATGGCACCTATAGCGATGAAGCGAAC CATGTGGATCCGTGCCTGCCGTGCACCGTGTGCGAAGATACCGAACGCCAGCTGCG CGAATGCACCCGCTGGGCGGATGCGGAATGCGAAGAAATTCCGGGCCGCGGCGGCG GCGGCCGCGAAAACGGCCGCGTGCCGCGCCCGCCGGATTGCCCGAAATGCCCGGCG CCGGAAATGCTGGGCGGCCCGAGCGTGTTTATTTTTCCGCCGAAACCGAAAGATACC CTGCTGATTGCGCGCACCCCGGAAGTGACCTGCGTGGTGGTGGATCTGGATCCGGAA GATCCGGAAGTGCAGATTAGCTGGTTTGTGGATGGCAAACAGATGCAGACCGCGAA AACCCAGCCGCGCGAAGAACAGTTTAACGGCACCTATCGCGTGGTGAGCGTGCTGC CGATTGGCCATCAGGATTGGCTGAAAGGCAAACAGTTTACCTGCAAAGTGAACAAC AAAGCGCTGCCGAGCCCGATTGAACGCACCATTAGCAAAGCGCGCGGCCAGGCGCA TCAGCCGAGCGTGTATGTGCTGCCGCCGAGCCGCGAAGAACTGAGCAAAAACACCG TGAGCCTGACCTGCCTGATTAAAGATTTTTTTCCGCCGGATATTGATGTGGAATGGC AGAGCAACGGCCAGCAGGAACCGGAAAGCAAATATCGCACCACCCCGCCGCAGCT GGATGAAGATGGCAGCTATTTTCTGTATAGCAAACTGAGCGTGGATAAAAGCCGCT GGCAGCGCGGCGATACCTTTATTTGCGCGGTGATGCATGAAGCGCTGCATAACCATT ATACCCAGAAAAGCCTGAGCCATAGCCCGGGCAAA Canine p75NTR ECD V133R (SEQ ID NO:55) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNT VCEECPDGTYSDEANHRDPCLPCTVCEDTERQLRECTRWADAECEEIPGR Canine p75NTR ECD V133R – canine IgGB wt Fc (SEQ ID NO:56) MEWSWVFLFFLSVTTGVHSKEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPC LDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEAC RVCEAGSGLVFSCQDRQNTVCEECPDGTYSDEANHRDPCLPCTVCEDTERQLRECTRW ADAECEEIPGRGGGGRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEV TCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGK QFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDV EWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNH YTQKSLSHSPGK Signal peptide - Canine p75-ECD - Linker GGGG - Canine Fc-B wt Canine p75NTR ECD V133R – canine IgGB wt Fc nucleic acid sequence (SEQ ID NO:57) ATGGAATGGAGCTGGGTGTTTCTGTTTTTTCTGAGCGTGACCACCGGCGTGCATAGC AAAGAAGCGTGCCCGACCGGCCTGTATACCCATAGCGGCGAATGCTGCAAAGCGTG CAACCTGGGCGAAGGCGTGGCGCAGCCGTGCGGCGCGAACCAGACCGTGTGCGAAC CGTGCCTGGATAGCGTGACCTTTAGCGATGTGGTGAGCGCGACCGAACCGTGCAAA CCGTGCACCGAATGCGTGGGCCTGCAGAGCATGAGCGCGCCGTGCGTGGAAGCGGA TGATGCGGTGTGCCGCTGCGCGTATGGCTATTATCAGGATGAAACCACCGGCCGCTG CGAAGCGTGCCGCGTGTGCGAAGCGGGCAGCGGCCTGGTGTTTAGCTGCCAGGATC GCCAGAACACCGTGTGCGAAGAATGCCCGGATGGCACCTATAGCGATGAAGCGAAC CATCGCGATCCGTGCCTGCCGTGCACCGTGTGCGAAGATACCGAACGCCAGCTGCG CGAATGCACCCGCTGGGCGGATGCGGAATGCGAAGAAATTCCGGGCCGCGGCGGCG GCGGCCGCGAAAACGGCCGCGTGCCGCGCCCGCCGGATTGCCCGAAATGCCCGGCG CCGGAAATGCTGGGCGGCCCGAGCGTGTTTATTTTTCCGCCGAAACCGAAAGATACC CTGCTGATTGCGCGCACCCCGGAAGTGACCTGCGTGGTGGTGGATCTGGATCCGGAA GATCCGGAAGTGCAGATTAGCTGGTTTGTGGATGGCAAACAGATGCAGACCGCGAA AACCCAGCCGCGCGAAGAACAGTTTAACGGCACCTATCGCGTGGTGAGCGTGCTGC CGATTGGCCATCAGGATTGGCTGAAAGGCAAACAGTTTACCTGCAAAGTGAACAAC AAAGCGCTGCCGAGCCCGATTGAACGCACCATTAGCAAAGCGCGCGGCCAGGCGCA TCAGCCGAGCGTGTATGTGCTGCCGCCGAGCCGCGAAGAACTGAGCAAAAACACCG TGAGCCTGACCTGCCTGATTAAAGATTTTTTTCCGCCGGATATTGATGTGGAATGGC AGAGCAACGGCCAGCAGGAACCGGAAAGCAAATATCGCACCACCCCGCCGCAGCT GGATGAAGATGGCAGCTATTTTCTGTATAGCAAACTGAGCGTGGATAAAAGCCGCT GGCAGCGCGGCGATACCTTTATTTGCGCGGTGATGCATGAAGCGCTGCATAACCATT ATACCCAGAAAAGCCTGAGCCATAGCCCGGGCAAA Canine p75NTR ECD D134L (SEQ ID NO:58) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNT VCEECPDGTYSDEANHVLPCLPCTVCEDTERQLRECTRWADAECEEIPGR Canine p75NTR ECD D134L – canine IgGB wt Fc (SEQ ID NO:59) MEWSWVFLFFLSVTTGVHSKEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPC LDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEAC RVCEAGSGLVFSCQDRQNTVCEECPDGTYSDEANHVLPCLPCTVCEDTERQLRECTRW ADAECEEIPGRGGGGRENGRVPRPPDCPKCPAPEMLGGPSVFIFPPKPKDTLLIARTPEV TCVVVDLDPEDPEVQISWFVDGKQMQTAKTQPREEQFNGTYRVVSVLPIGHQDWLKGK QFTCKVNNKALPSPIERTISKARGQAHQPSVYVLPPSREELSKNTVSLTCLIKDFFPPDIDV EWQSNGQQEPESKYRTTPPQLDEDGSYFLYSKLSVDKSRWQRGDTFICAVMHEALHNH YTQKSLSHSPGK Signal peptide - Canine p75-ECD - Linker GGGG - Canine Fc-B wt Canine p75NTR ECD D134L – canine IgGB wt Fc nucleic acid sequence (SEQ ID NO:60) ATGGAATGGAGCTGGGTGTTTCTGTTTTTTCTGAGCGTGACCACCGGCGTGCATAGC AAAGAAGCGTGCCCGACCGGCCTGTATACCCATAGCGGCGAATGCTGCAAAGCGTG CAACCTGGGCGAAGGCGTGGCGCAGCCGTGCGGCGCGAACCAGACCGTGTGCGAAC CGTGCCTGGATAGCGTGACCTTTAGCGATGTGGTGAGCGCGACCGAACCGTGCAAA CCGTGCACCGAATCGTGGGCCTGCAGAGCATGAGCGCGCCGTGCGTGGAAGCGGAT GATGCGGTGTGCCGCTGCGCGTATGGCTATTATCAGGATGAAACCACCGGCCGCTGC GAAGCGTGCCGCGTGTGCGAAGCGGGCAGCGGCCTGGTGTTTAGCTGCCAGGATCG CCAGAACACCGTGTGCGAAGAATGCCCGGATGGCACCTATAGCGATGAAGCGAACC ATGTGCTGCCGTGCCTGCCGTGCACCGTGTGCGAAGATACCGAACGCCAGCTGCGC GAATGCACCCGCTGGGCGGATGCGGAATGCGAAGAAATTCCGGGCCGCGGCGGCGG CGGCCGCGAAAACGGCCGCGTGCCGCGCCCGCCGGATTGCCCGAAATGCCCGGCGC CGGAAATGCTGGGCGGCCCGAGCGTGTTTATTTTTCCGCCGAAACCGAAAGATACCC TGCTGATTGCGCGCACCCCGGAAGTGACCTGCGTGGTGGTGGATCTGGATCCGGAA GATCCGGAAGTGCAGATTAGCTGGTTTGTGGATGGCAAACAGATGCAGACCGCGAA AACCCAGCCGCGCGAAGAACAGTTTAACGGCACCTATCGCGTGGTGAGCGTGCTGC CGATTGGCCATCAGGATTGGCTGAAAGGCAAACAGTTTACCTGCAAAGTGAACAAC AAAGCGCTGCCGAGCCCGATTGAACGCACCATTAGCAAAGCGCGCGGCCAGGCGCA TCAGCCGAGCGTGTATGTGCTGCCGCCGAGCCGCGAAGAACTGAGCAAAAACACCG TGAGCCTGACCTGCCTGATTAAAGATTTTTTTCCGCCGGATATTGATGTGGAATGGC AGAGCAACGGCCAGCAGGAACCGGAAAGCAAATATCGCACCACCCCGCCGCAGCT GGATGAAGATGGCAGCTATTTTCTGTATAGCAAACTGAGCGTGGATAAAAGCCGCT GGCAGCGCGGCGATACCTTTATTTGCGCGGTGATGCATGAAGCGCTGCATAACCATT ATACCCAGAAAAGCCTGAGCCATAGCCCGGGCAAA Feline p75NTR ECD E75T (SEQ ID NO:61) KEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEATDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIP Feline p75NTR ECD E75T – Feline IgG1 (SEQ ID NO:62) MDGPRPLLLLLPLLLGVSLGGAKEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVC EPCLDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEATDAVCRCAYGYYQDETTGRC EACRVCEAGSGLVFSCQDRQNTVCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECT RWADAECEEIPGGGGVRKTDHPPGPKPCDCPKCPAPEMLGGPSIFIFPPKPKDTLSISRTP EVTCLVVDLGPDDSDVQITWFVDNTQVYTAKTSPREEQFNSTYRVVSVLPILHQDWLK GKEFKCKVNSKSLPSPIERTISKAKGQPHEPQVYVLPPAQEELSRNKVSVTCLIKSFHPPDI AVEWEITGQPEPENNYRTTPPQLDSDGTYFVYSKLSVDRSHWQRGNTYTCSVSHEALHS HHTQKSLTQSPGK Signal peptide - Feline p75-ECD - Linker GGGG - Feline Fc-IgG1 Feline p75NTR ECD S109Y (SEQ ID NO:63) KEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFYCQDRQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIP Feline p75NTR ECD S109Y – Feline Fc IgG1 (SEQ ID NO:64) MDGPRPLLLLLPLLLGVSLGGAKEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVC EPCLDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRC EACRVCEAGSGLVFYCQDRQNTVCEECPDGTYSDEANHVDPCLPCTVCEDTERQLREC TRWADAECEEIPGGGGVRKTDHPPGPKPCDCPKCPAPEMLGGPSIFIFPPKPKDTLSISRT PEVTCLVVDLGPDDSDVQITWFVDNTQVYTAKTSPREEQFNSTYRVVSVLPILHQDWLK GKEFKCKVNSKSLPSPIERTISKAKGQPHEPQVYVLPPAQEELSRNKVSVTCLIKSFHPPDI AVEWEITGQPEPENNYRTTPPQLDSDGTYFVYSKLSVDRSHWQRGNTYTCSVSHEALHS HHTQKSLTQSPGK Signal peptide - Feline p75-ECD - Linker GGGG - Feline Fc-IgG1 Feline p75NTR ECD S109H (SEQ ID NO:65) KEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFHCQDRQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIP Feline p75NTR ECD S109H – Feline Fc IgG1 (SEQ ID NO:66) MDGPRPLLLLLPLLLGVSLGGAKEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVC EPCLDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRC EACRVCEAGSGLVFHCQDRQNTVCEECPDGTYSDEANHVDPCLPCTVCEDTERQLREC TRWADAECEEIPGGGGVRKTDHPPGPKPCDCPKCPAPEMLGGPSIFIFPPKPKDTLSISRT PEVTCLVVDLGPDDSDVQITWFVDNTQVYTAKTSPREEQFNSTYRVVSVLPILHQDWLK GKEFKCKVNSKSLPSPIERTISKAKGQPHEPQVYVLPPAQEELSRNKVSVTCLIKSFHPPDI AVEWEITGQPEPENNYRTTPPQLDSDGTYFVYSKLSVDRSHWQRGNTYTCSVSHEALHS HHTQKSLTQSPGK Signal peptide - Feline p75-ECD - Linker GGGG - Feline Fc-IgG1 Feline p75NTR ECD V133R (SEQ ID NO:67) KEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNT VCEECPDGTYSDEANHRDPCLPCTVCEDTERQLRECTRWADAECEEIP Feline p75NTR ECD V133R – Feline Fc IgG1 (SEQ ID NO:68) MDGPRPLLLLLPLLLGVSLGGAKEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVC EPCLDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRC EACRVCEAGSGLVFSCQDRQNTVCEECPDGTYSDEANHRDPCLPCTVCEDTERQLRECT RWADAECEEIPGGGGVRKTDHPPGPKPCDCPKCPAPEMLGGPSIFIFPPKPKDTLSISRTP EVTCLVVDLGPDDSDVQITWFVDNTQVYTAKTSPREEQFNSTYRVVSVLPILHQDWLK GKEFKCKVNSKSLPSPIERTISKAKGQPHEPQVYVLPPAQEELSRNKVSVTCLIKSFHPPDI AVEWEITGQPEPENNYRTTPPQLDSDGTYFVYSKLSVDRSHWQRGNTYTCSVSHEALHS HHTQKSLTQSPGK Signal peptide - Feline p75-ECD - Linker GGGG - Feline Fc-IgG1 Feline p75NTR ECD D134L (SEQ ID NO:69) KEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDRQNT VCEECPDGTYSDEANHVLPCLPCTVCEDTERQLRECTRWADAECEEIP Feline p75NTR ECD D134L – Feline Fc IgG1 (SEQ ID NO:70) MDGPRPLLLLLPLLLGVSLGGAKEACPTGLFTHSGECCKACNLGEGVAQPCGANQTVC EPCLDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRC EACRVCEAGSGLVFSCQDRQNTVCEECPDGTYSDEANHVLPCLPCTVCEDTERQLRECT RWADAECEEIPGGGGVRKTDHPPGPKPCDCPKCPAPEMLGGPSIFIFPPKPKDTLSISRTP EVTCLVVDLGPDDSDVQITWFVDNTQVYTAKTSPREEQFNSTYRVVSVLPILHQDWLK GKEFKCKVNSKSLPSPIERTISKAKGQPHEPQVYVLPPAQEELSRNKVSVTCLIKSFHPPDI AVEWEITGQPEPENNYRTTPPQLDSDGTYFVYSKLSVDRSHWQRGNTYTCSVSHEALHS HHTQKSLTQSPGK Signal peptide - Feline p75-ECD - Linker GGGG - Feline Fc-IgG1 Human p75NTR protein (SEQ ID NO:71) >sp|P08138|TNR16_HUMAN Tumor necrosis factor receptor superfamily member 16 OS=Homo sapiens OX=9606 GN=NGFR PE=1 SV=1 MGAGATGRAMDGPRLLLLLLLGVSLGGAKEACPTGLYTHSGECCKACNLGEGVAQPC GANQTVCEPCLDSVTFSDVVSATEPCKPCTECVGLQSMSAPCVEADDAVCRCAYGYYQ DETTGRCEACRVCEAGSGLVFSCQDKQNTVCEECPDGTYSDEANHVDPCLPCTVCEDT ERQLRECTRWADAECEEIPGRWITRSTPPEGSDSTAPSTQEPEAPPEQDLIASTVAGVVTT VMGSSQPVVTRGTTDNLIPVYCSILAAVVVGLVAYIAFKRWNSCKQNKQGANSRPVNQ TPPPEGEKLHSDSGISVDSQSLHDQQPHTQTASGQALKGDGGLYSSLPPAKREEVEKLLN GSAGDTWRHLAGELGYQPEHIDSFTHEACPVRALLASWATQDSATLDALLAALRRIQR ADLVESLCSESTATSPV Full p75NTR aa sequence including signal peptide, ECD, transmembrane and intracellular domains Human p75NTR nucleic acid sequence (SEQ ID NO:72) ATGGGCGCCGGCGCCACCGGCAGGGCCATGGACGGCCCCAGGCTGCTGCTGCTGCT GCTGCTGGGCGTGAGCCTGGGCGGCGCCAAGGAGGCCTGCCCCACCGGCCTGTACA CCCACAGCGGCGAGTGCTGCAAGGCCTGCAACCTGGGCGAGGGCGTGGCCCAGCCC TGCGGCGCCAACCAGACCGTGTGCGAGCCCTGCCTGGACAGCGTGACCTTCAGCGA CGTGGTGAGCGCCACCGAGCCCTGCAAGCCCTGCACCGAGTGCGTGGGCCTGCAGA GCATGAGCGCCCCCTGCGTGGAGGCCGACGACGCCGTGTGCAGGTGCGCCTACGGC TACTACCAGGACGAGACCACCGGCAGGTGCGAGGCCTGCAGGGTGTGCGAGGCCGG CAGCGGCCTGGTGTTCAGCTGCCAGGACAAGCAGAACACCGTGTGCGAGGAGTGCC CCGACGGCACCTACAGCGACGAGGCCAACCACGTGGACCCCTGCCTGCCCTGCACC GTGTGCGAGGACACCGAGAGGCAGCTGAGGGAGTGCACCAGGTGGGCCGACGCCG AGTGCGAGGAGATCCCCGGCAGGTGGATCACCAGGAGCACCCCCCCCGAGGGCAGC GACAGCACCGCCCCCAGCACCCAGGAGCCCGAGGCCCCCCCCGAGCAGGACCTGAT CGCCAGCACCGTGGCCGGCGTGGTGACCACCGTGATGGGCAGCAGCCAGCCCGTGG TGACCAGGGGCACCACCGACAACCTGATCCCCGTGTACTGCAGCATCCTGGCCGCC GTGGTGGTGGGCCTGGTGGCCTACATCGCCTTCAAGAGGTGGAACAGCTGCAAGCA GAACAAGCAGGGCGCCAACAGCAGGCCCGTGAACCAGACCCCCCCCCCCGAGGGC GAGAAGCTGCACAGCGACAGCGGCATCAGCGTGGACAGCCAGAGCCTGCACGACC AGCAGCCCCACACCCAGACCGCCAGCGGCCAGGCCCTGAAGGGCGACGGCGGCCTG TACAGCAGCCTGCCCCCCGCCAAGAGGGAGGAGGTGGAGAAGCTGCTGAACGGCA GCGCCGGCGACACCTGGAGGCACCTGGCCGGCGAGCTGGGCTACCAGCCCGAGCAC ATCGACAGCTTCACCCACGAGGCCTGCCCCGTGAGGGCCCTGCTGGCCAGCTGGGC CACCCAGGACAGCGCCACCCTGGACGCCCTGCTGGCCGCCCTGAGGAGGATCCAGA GGGCCGACCTGGTGGAGAGCCTGTGCAGCGAGAGCACCGCCACCAGCCCCGTG Human p75NTR protein ECD with stalk region (SEQ ID NO:73) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDKQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGRWITRSTPPE GSDSTAPSTQEPEAPPEQDLIASTVAGVVTTVM The WT ECD region includes the stalk region (underlined) and alpha and gamma secretase cleavage 3’ of the stalk region (in bold) Human p75NTR ECD nucleic acid sequence (SEQ ID NO:74) AAGGAGGCCTGCCCCACCGGCCTGTACACCCACAGCGGCGAGTGCTGCAAGGCCTG CAACCTGGGCGAGGGCGTGGCCCAGCCCTGCGGCGCCAACCAGACCGTGTGCGAGC CCTGCCTGGACAGCGTGACCTTCAGCGACGTGGTGAGCGCCACCGAGCCCTGCAAG CCCTGCACCGAGTGCGTGGGCCTGCAGAGCATGAGCGCCCCCTGCGTGGAGGCCGA CGACGCCGTGTGCAGGTGCGCCTACGGCTACTACCAGGACGAGACCACCGGCAGGT GCGAGGCCTGCAGGGTGTGCGAGGCCGGCAGCGGCCTGGTGTTCAGCTGCCAGGAC AAGCAGAACACCGTGTGCGAGGAGTGCCCCGACGGCACCTACAGCGACGAGGCCA ACCACGTGGACCCCTGCCTGCCCTGCACCGTGTGCGAGGACACCGAGAGGCAGCTG AGGGAGTGCACCAGGTGGGCCGACGCCGAGTGCGAGGAGATCCCCGGCAGGTGGA TCACCAGGAGCACCCCCCCCGAGGGCAGCGACAGCACCGCCCCCAGCACCCAGGAG CCCGAGGCCCCCCCCGAGCAGGACCTGATCGCCAGCACCGTGGCCGGCGTGGTGAC CACCGTGATG Human ECD of p75NTR stalk region protein (SEQ ID NO:75) GRWITRSTPPEGSDSTAPSTQEPEAPPEQDLIASTVAGVVTTVM The WT ECD stalk region (underlined) and alpha and gamma secretase cleavage 3’ of the stalk region (in bold) Human ECD of p75NTR stalk region nucleic acid sequence (SEQ ID NO:76) GGCAGGTGGATCACCAGGAGCACCCCCCCCGAGGGCAGCGACAGCACCGCCCCCAG CACCCAGGAGCCCGAGGCCCCCCCCGAGCAGGACCTGATCGCCAGCACCGTGGCCG GCGTGGTGACCACCGTGATG Human IgG1 (SEQ ID NO:77) EPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKF NWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPI EKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNY KTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK Human IgG2 (SEQ ID NO:78) ERKCCVECPPCPAPPVAGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVQFNWY VDGVEVHNAKTKPREEQFNSTFRVVSVLTVVHQDWLNGKEYKCKVSNKGLPAPIEKTI SKTKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDISVEWESNGQPENNYKTTP PMLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK Human IgG3 (SEQ ID NO:79) ELKTPLGDTTHTCPRCPEPKSCDTPPPCPRCPEPKSCDTPPPCPRCPEPKSCDTPPPCPRCP APELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVQFKWYVDGVEVHNAKT KPREEQYNSTFRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKTKGQPREPQV YTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESSGQPENNYNTTPPMLDSDGSFFLYS KLTVDKSRWQQGNIFSCSVMHEALHNRFTQKSLSLSPGK Human IgG4 (SEQ ID NO:80) ESKYGPPCPSCPAPEFLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWY VDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTIS KAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPP VLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK PetML308_Human p75NTR ECD full stalk IgG1 (SEQ ID NO:81) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDKQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGRWITRSTPPE GSDSTAPSTQEPEAPPEQDLIASTVAGVVTTVMGGGGEPKSCDKTHTCPPCPAPELLGGP SVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQY NSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSR DELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDK SRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK PetML309_Human p75NTR ECD partial stalk IgG1 (SEQ ID NO:82) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDKQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGRWITRSTPPE GGGGEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDP EVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKA LPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPE NNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG K PetML319_Human p75NTR ECD no stalk IgG1 (SEQ ID NO:83) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDKQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGGGGEPKSCDK THTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDG VEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKA KGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK Human p75NTR ECD E75T (SEQ ID NO:84) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEATDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDKQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIP Human p75NTR ECD E75T – human IgG1 Fc (SEQ ID NO:85) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEATDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDKQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGGGGEPKSCDK THTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDG VEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKA KGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK Human p75NTR ECD E75T – human IgG1 Fc nucleic acid sequence (SEQ ID NO:86) AAGGAGGCCTGCCCCACCGGCCTGTACACCCACAGCGGCGAGTGCTGCAAGGCCTG CAACCTGGGCGAGGGCGTGGCCCAGCCCTGCGGCGCCAACCAGACCGTGTGCGAGC CCTGCCTGGACAGCGTGACCTTCAGCGACGTGGTGAGCGCCACCGAGCCCTGCAAG CCCTGCACCGAGTGCGTGGGCCTGCAGAGCATGAGCGCCCCCTGCGTGGAGGCCAC CGACGCCGTGTGCGGTGCGCCTACGGCTACTACCAGGACGAGACCACCGGCAGGTG CGAGGCCTGCAGGGTGTGCGAGGCCGGCAGCGGCCTGGTGTTCAGCTGCCAGGACA AGCAGAACACCGTGTGCGAGGAGTGCCCCGACGGCACCTACAGCGACGAGGCCAAC CACGTGGACCCCTGCCTGCCCTGCACCGTGTGCGAGGACACCGAGAGGCAGCTGAG GGAGTGCACCAGGTGGGCCGACGCCGAGTGCGAGGAGATCCCCGGCGGCGGCGGC GAGCCCAAGAGCTGCGACAAGACCCACACCTGCCCCCCCTGCCCCGCCCCCGAGCT GCTGGGCGGCCCCAGCGTGTTCCTGTTCCCCCCCAAGCCCAAGGACACCCTGATGAT CAGCAGGACCCCCGAGGTGACCTGCGTGGTGGTGGACGTGAGCCACGAGGACCCCG AGGTGAAGTTCAACTGGTACGTGGACGGCGTGGAGGTGCACAACGCCAAGACCAAG CCCAGGGAGGAGCAGTACAACAGCACCTACAGGGTGGTGAGCGTGCTGACCGTGCT GCACCAGGACTGGCTGAACGGCAAGGAGTACAAGTGCAAGGTGAGCAACAAGGCC CTGCCCGCCCCCATCGAGAAGACCATCAGCAAGGCCAAGGGCCAGCCCAGGGAGCC CCAGGTGTACACCCTGCCCCCCAGCAGGGACGAGCTGACCAAGAACCAGGTGAGCC TGACCTGCCTGGTGAAGGGCTTCTACCCCAGCGACATCGCCGTGGAGTGGGAGAGC CAGCTTCTTCCTGTACAGCAAGCTGACCGTGGACAAGAGCAGGTGGCAGCAGGGCA ACGTGTTCAGCTGCAGCGTGATGCACGAGGCCCTGCACAACCACTACACCCAGAAG AGCCTGAGCCTGAGCCCCGGCAAG Human p75NTR ECD S109Y (SEQ ID NO:87) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFYCQDKQNT VCEE CPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIP Human p75NTR ECD S109Y – human IgG1 Fc (SEQ ID NO:88) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFYCQDKQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGGGGEPKSCDK THTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDG VEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKA KGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK Human p75NTR ECD S109Y – human IgG1 Fc nucleic acid sequence (SEQ ID NO:89) AAGGAGGCCTGCCCCACCGGCCTGTACACCCACAGCGGCGAGTGCTGCAAGGCCTG CAACCTGGGCGAGGGCGTGGCCCAGCCCTGCGGCGCCAACCAGACCGTGTGCGAGC CCTGCCTGGACAGCGTGACCTTCAGCGACGTGGTGAGCGCCACCGAGCCCTGCAAG CCCTGCACCGAGTGCGTGGGCCTGCAGAGCATGAGCGCCCCCTGCGTGGAGGCCGA CGACGCCGTGTGCAGGTGCGCCTACGGCTACTACCAGGACGAGACCACCGGCAGGT GCGAGGCCTGCAGGGTGTGCGAGGCCGGCAGCGGCCTGGTGTTCTACTGCCAGGAC AAGCAGAACACCGTGTGCGAGGAGTGCCCCGACGGCACCTACAGCGACGAGGCCA ACCACGTGGACCCCTGCCTGCCCTGCACCGTGTGCGAGGACACCGAGAGGCAGCTG AGGGAGTGCACCAGGTGGGCCGACGCCGAGTGCGAGGAGATCCCCGGCGGCGGCG GCGAGCCCAAGAGCTGCGACAAGACCCACACCTGCCCCCCCTGCCCCGCCCCCGAG CTGCTGGGCGGCCCCAGCGTGTTCCTGTTCCCCCCCAAGCCCAAGGACACCCTGATG ATCAGCAGGACCCCCGAGGTGACCTGCGTGGTGGTGGACGTGAGCCACGAGGACCC CGAGGTGAAGTTCAACTGGTACGTGGACGGCGTGGAGGTGCACAACGCCAAGACCA AGCCCAGGGAGGAGCAGTACAACAGCACCTACAGGGTGGTGAGCGTGCTGACCGTG CTGCACCAGGACTGGCTGAACGGCAAGGAGTACAAGTGCAAGGTGAGCAACAAGG CCCTGCCCGCCCCCATCGAGAAGACCATCAGCAAGGCCAAGGGCCAGCCCAGGGAG CCCCAGGTGTACACCCTGCCCCCCAGCAGGGACGAGCTGACCAAGAACCAGGTGAG CCTGACCTGCCTGGTGAAGGGCTTCTACCCCAGCGACATCGCCGTGGAGTGGGAGA GCAACGGCCAGCCCGAGAACAACTACAAGACCACCCCCCCCGTGCTGGACAGCGAC GGCAGCTTCTTCCTGTACAGCAAGCTGACCGTGGACAAGAGCAGGTGGCAGCAGGG CAACGTGTTCAGCTGCAGCGTGATGCACGAGGCCCTGCACAACCACTACACCCAGA AGAGCCTGAGCCTGAGCCCCGGCAAG Human p75NTR ECD S109H (SEQ ID NO:90) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFHCQDKQNT VCEE CPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIP Human p75NTR ECD S109H – human IgG1 Fc (SEQ ID NO:91) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFHCQDKQNT VCEECPDGTYSDEANHVDPCLPCTVCEDTERQLRECTRWADAECEEIPGGGGEPKSCDK THTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDG VEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKA KGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK Human p75NTR ECD S109H – human IgG1 Fc nucleic acid sequence (SEQ ID NO:92) AAGGAGGCCTGCCCCACCGGCCTGTACACCCACAGCGGCGAGTGCTGCAAGGCCTG CAACCTGGGCGAGGGCGTGGCCCAGCCCTGCGGCGCCAACCAGACCGTGTGCGAGC CCTGCCTGGACAGCGTGACCTTCAGCGACGTGGTGAGCGCCACCGAGCCCTGCAAG CCCTGCACCGAGTGCGTGGGCCTGCAGAGCATGAGCGCCCCCTGCGTGGAGGCCGA CGACGCCGTGTGCAGGTGCGCCTACGGCTACTACCAGGACGAGACCACCGGCAGGT GCGAGGCCTGCAGGGTGTGCGAGGCCGGCAGCGGCCTGGTGTTCCACTGCCAGGAC AAGCAGAACACCGTGTGCGAGGAGTGCCCCGACGGCACCTACAGCGACGAGGCCA ACCACGTGGACCCCTGCCTGCCCTGCACCGTGTGCGAGGACACCGAGAGGCAGCTG AGGGAGTGCACCAGGTGGGCCGACGCCGAGTGCGAGGAGATCCCCGGCGGCGGCG GCGAGCCCAAGAGCTGCGACAAGACCCACACCTGCCCCCCCTGCCCCGCCCCCGAG CTGCTGGGCGGCCCCAGCGTGTTCCTGTTCCCCCCCAAGCCCAAGGACACCCTGATG ATCAGCAGGACCCCCGAGGTGACCTGCGTGGTGGTGGACGTGAGCCACGAGGACCC CGAGGTGAAGTTCAACTGGTACGTGGACGGCGTGGAGGTGCACAACGCCAAGACCA AGCCCAGGGAGGAGCAGTACAACAGCACCTACAGGGTGGTGAGCGTGCTGACCGTG CTGCACCAGGACTGGCTGAACGGCAAGGAGTACAAGTGCAAGGTGAGCAACAAGG CCCTGCCCGCCCCCATCGAGAAGACCATCAGCAAGGCCAAGGGCCAGCCCAGGGAG CCCCAGGTGTACACCCTGCCCCCCAGCAGGGACGAGCTGACCAAGAACCAGGTGAG CCTGACCTGCCTGGTGAAGGGCTTCTACCCCAGCGACATCGCCGTGGAGTGGGAGA GCAACGGCCAGCCCGAGAACAACTACAAGACCACCCCCCCCGTGCTGGACAGCGAC GGCAGCTTCTTCCTGTACAGCAAGCTGACCGTGGACAAGAGCAGGTGGCAGCAGGG CAACGTGTTCAGCTGCAGCGTGATGCACGAGGCCCTGCACAACCACTACACCCAGA AGAGCCTGAGCCTGAGCCCCGGCAAG Human p75NTR ECD V133R (SEQ ID NO:93) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDKQNT VCEE CPDGTYSDEANHRDPCLPCTVCEDTERQLRECTRWADAECEEIP Human p75NTR ECD V133R – human IgG1 Fc (SEQ ID NO:94) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDKQNT VCEECPDGTYSDEANHRDPCLPCTVCEDTERQLRECTRWADAECEEIPGGGGEPKSCDK THTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDG VEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKA KGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK Human p75NTR ECD V133R – human IgG1 Fc nucleic acid sequence (SEQ ID NO:95) AAGGAGGCCTGCCCCACCGGCCTGTACACCCACAGCGGCGAGTGCTGCAAGGCCTG CAACCTGGGCGAGGGCGTGGCCCAGCCCTGCGGCGCCAACCAGACCGTGTGCGAGC CCTGCCTGGACAGCGTGACCTTCAGCGACGTGGTGAGCGCCACCGAGCCCTGCAAG CCCTGCACCGAGTGCGTGGGCCTGCAGAGCATGAGCGCCCCCTGCGTGGAGGCCGA CGACGCCGTGTGCAGGTGCGCCTACGGCTACTACCAGGACGAGACCACCGGCAGGT GCGAGGCCTGCAGGGTGTGCGAGGCCGGCAGCGGCCTGGTGTTCAGCTGCCAGGAC AAGCAGAACACCGTGTGCGAGGAGTGCCCCGACGGCACCTACAGCGACGAGGCCA ACCACAGGGACCCCTGCCTGCCCTGCACCGTGTGCGAGGACACCGAGAGGCAGCTG AGGGAGTGCACCAGGTGGGCCGACGCCGAGTGCGAGGAGATCCCCGGCGGCGGCG GCGAGCCCAAGAGCTGCGACAAGACCCACACCTGCCCCCCCTGCCCCGCCCCCGAG CTGCTGGGCGGCCCCAGCGTGTTCCTGTTCCCCCCCAAGCCCAAGGACACCCTGATG ATCAGCAGGACCCCCGAGGTGACCTGCGTGGTGGTGGACGTGAGCCACGAGGACCC CGAGGTGAAGTTCAACTGGTACGTGGACGGCGTGGAGGTGCACAACGCCAAGACCA AGCCCAGGGAGGAGCAGTACAACAGCACCTACAGGGTGGTGAGCGTGCTGACCGTG CTGCACCAGGACTGGCTGAACGGCAAGGAGTACAAGTGCAAGGTGAGCAACAAGG CCCTGCCCGCCCCCATCGAGAAGACCATCAGCAAGGCCAAGGGCCAGCCCAGGGAG CCCCAGGTGTACACCCTGCCCCCCAGCAGGGACGAGCTGACCAAGAACCAGGTGAG CCTGACCTGCCTGGTGAAGGGCTTCTACCCCAGCGACATCGCCGTGGAGTGGGAGA GCAACGGCCAGCCCGAGAACAACTACAAGACCACCCCCCCCGTGCTGGACAGCGAC GGCAGCTTCTTCCTGTACAGCAAGCTGACCGTGGACAAGAGCAGGTGGCAGCAGGG CAACGTGTTCAGCTGCAGCGTGATGCACGAGGCCCTGCACAACCACTACACCCAGA AGAGCCTGAGCCTGAGCCCCGGCAAG Human p75NTR ECD D134L (SEQ ID NO:96) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDKQNT VCEE CPDGTYSDEANHVLPCLPCTVCEDTERQLRECTRWADAECEEIP Human p75NTR ECD D134L – human IgG1 Fc (SEQ ID NO:97) KEACPTGLYTHSGECCKACNLGEGVAQPCGANQTVCEPCLDSVTFSDVVSATEPCKPCT ECVGLQSMSAPCVEADDAVCRCAYGYYQDETTGRCEACRVCEAGSGLVFSCQDKQNT VCEECPDGTYSDEANHVLPCLPCTVCEDTERQLRECTRWADAECEEIPGGGGEPKSCDK VEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKA KGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK Human p75NTR ECD D134L – human IgG1 Fc nucleic acid sequence (SEQ ID NO:98) AAGGAGGCCTGCCCCACCGGCCTGTACACCCACAGCGGCGAGTGCTGCAAGGCCTG CAACCTGGGCGAGGGCGTGGCCCAGCCCTGCGGCGCCAACCAGACCGTGTGCGAGC CCTGCCTGGACAGCGTGACCTTCAGCGACGTGGTGAGCGCCACCGAGCCCTGCAAG CCCTGCACCGAGTGCGTGGGCCTGCAGAGCATGAGCGCCCCCTGCGTGGAGGCCGA CGACGCCGTGTGCAGGTGCGCCTACGGCTACTACCAGGACGAGACCACCGGCAGGT GCGAGGCCTGCAGGGTGTGCGAGGCCGGCAGCGGCCTGGTGTTCAGCTGCCAGGAC AAGCAGAACACCGTGTGCGAGGAGTGCCCCGACGGCACCTACAGCGACGAGGCCA ACCACGTGCTGCCCTGCCTGCCCTGCACCGTGTGCGAGGACACCGAGAGGCAGCTG AGGGAGTGCACCAGGTGGGCCGACGCCGAGTGCGAGGAGATCCCCGGCGGCGGCG GCGAGCCCAAGAGCTGCGACAAGACCCACACCTGCCCCCCCTGCCCCGCCCCCGAG CTGCTGGGCGGCCCCAGCGTGTTCCTGTTCCCCCCCAAGCCCAAGGACACCCTGATG ATCAGCAGGACCCCCGAGGTGACCTGCGTGGTGGTGGACGTGAGCCACGAGGACCC CGAGGTGAAGTTCAACTGGTACGTGGACGGCGTGGAGGTGCACAACGCCAAGACCA AGCCCAGGGAGGAGCAGTACAACAGCACCTACAGGGTGGTGAGCGTGCTGACCGTG CTGCACCAGGACTGGCTGAACGGCAAGGAGTACAAGTGCAAGGTGAGCAACAAGG CCCTGCCCGCCCCCATCGAGAAGACCATCAGCAAGGCCAAGGGCCAGCCCAGGGAG CCCCAGGTGTACACCCTGCCCCCCAGCAGGGACGAGCTGACCAAGAACCAGGTGAG CCTGACCTGCCTGGTGAAGGGCTTCTACCCCAGCGACATCGCCGTGGAGTGGGAGA GCAACGGCCAGCCCGAGAACAACTACAAGACCACCCCCCCCGTGCTGGACAGCGAC GGCAGCTTCTTCCTGTACAGCAAGCTGACCGTGGACAAGAGCAGGTGGCAGCAGGG CAACGTGTTCAGCTGCAGCGTGATGCACGAGGCCCTGCACAACCACTACACCCAGA AGAGCCTGAGCCTGAGCCCCGGCAAG Examples of p75NTR proteins of the invention from camels and pigs are incorporated in the Sequence Listing XML as follows: Camel p75NTR protein (SEQ IDNO:99) Camel p75NTR nucleic acid sequence (SEQ IDNO:100) Camel p75NTR protein ECD (SEQ IDNO:101) Camel p75NTR protein ECD nucleic acid sequence (SEQ IDNO:102) Camel p75NTR ECD E75T (SEQ IDNO:103) Camel p75NTR ECD S109Y (SEQ IDNO:104) Camel p75NTR ECD S109H (SEQ IDNO:105) Camel p75NTR ECD V133R (SEQ IDNO:106) Camel p75NTR ECD D134L (SEQ IDNO:107) Pig p75NTR protein (SEQ IDNO:108) Pig p75NTR nucleic acid sequence (SEQ IDNO:109) Pig p75NTR protein ECD (SEQ IDNO:110) Pig p75NTR protein ECD nucleic acid sequence (SEQ IDNO:111) Pig p75NTR ECD E75T (SEQ IDNO:112) Pig p75NTR ECD S109Y (SEQ IDNO:113) Pig p75NTR ECD S109H (SEQ IDNO:114) Pig p75NTR ECD V133R (SEQ IDNO:115) Pig p75NTR ECD D134L (SEQ IDNO:116) Equine p75NTR protein ECD (SEQ ID NO:118) Equine p75NTR protein ECD nucleic acid sequence (SEQ ID NO:119) Equine p75NTR ECD E75T (SEQ ID NO:120) Equine p75NTR ECD S109Y (SEQ ID NO:121) Equine p75NTR ECD S109H (SEQ ID NO:122) Equine p75NTR ECD V133R (SEQ ID NO:123) Equine p75NTR ECD D134L (SEQ ID NO:124) Bovine p75NTR protein ECD (SEQ ID NO:125) Bovine p75NTR protein ECD nucleic acid sequence (SEQ ID NO:126) Bovine p75NTR ECD E75T (SEQ ID NO:127) Bovine p75NTR ECD S109Y (SEQ ID NO:128) Bovine p75NTR ECD S109H (SEQ ID NO:129) Bovine p75NTR ECD V133R (SEQ ID NO:130) Bovine p75NTR ECD D134L (SEQ ID NO:131)

Claims

WHAT IS CLAIMED IS: 1. An isolated polypeptide comprising a companion animal p75neurotrophin receptor (p75NTR) extracellular domain, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134.

2. The isolated polypeptide according to claim 1, wherein the variant amino acid at position 75 of p75NTR comprises a polar side chain, optionally wherein the variant amino acid is selected from serine, threonine, tyrosine, tryptophan, asparagine, glutamine or cysteine, preferably threonine.

3. The isolated polypeptide according to claim 1 or 2, wherein the variant amino acid at position 109 of p75NTR comprises an aromatic side chain, optionally wherein the variant amino acid is selected from histidine, tyrosine, phenylalanine, or tryptophan.

4. The isolated polypeptide according to any preceding claim, wherein the variant amino acid at position 133 of p75NTR comprises a charged side chain.

5. The isolated polypeptide according to any preceding claim, wherein the variant amino acid at position 133 of p75NTR is selected from arginine, histidine, lysine, aspartic acid, or glutamic acid.

6. The isolated polypeptide according to any of claims 1 to 4, wherein the variant amino acid at position 133 of p75NTR comprises a negatively charged side chain, optionally wherein the variant amino acid is selected from arginine, histidine, or lysine, preferably arginine.

7. The isolated polypeptide according to any preceding claim, wherein the variant amino acid at position 134 of p75NTR comprises a hydrophobic side chain.

8. The isolated polypeptide according to any preceding claim, wherein the variant amino acid at position 134 of p75NTR is selected from alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine, or tryptophan.

9. The isolated polypeptide according to any of claims 1 to 7, wherein the variant amino acid at position 134 of p75NTR comprises a non-aromatic hydrophobic side chain, optionally wherein the variant amino acid is selected from alanine, valine, isoleucine, leucine, or methionine, preferably leucine.

10. The isolated polypeptide according to any preceding claim, wherein the companion animal is a cat, dog, pig, cow, horse or camel.

11. The isolated polypeptide according to any preceding claim, wherein the companion animal is a dog and the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 46, SEQ ID NO: 49, SEQ ID NO: 52, SEQ ID NO:55 or SEQ ID NO: 58; or wherein the companion animal is a cat and the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 61, SEQ ID NO: 63, SEQ ID NO: 65, SEQ ID NO: 67 or SEQ ID NO: 69; or wherein the companion animal is a pig and the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 112, SEQ ID NO: 113, SEQ ID NO: 114, SEQ ID NO: 115 or SEQ ID NO: 116; or wherein the companion animal is a horse and the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 120, SEQ ID NO: 121, SEQ ID NO: 122, SEQ ID NO: 123 or SEQ ID NO: 124; or wherein the companion animal is a cow and the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 127, SEQ ID NO: 128, SEQ ID NO: 129, SEQ ID NO: 130 or SEQ ID NO: 131; or wherein the companion animal is a camel and the p75NTR comprises or consists of a sequence selected from SEQ ID NO: 103, SEQ ID NO: 104, SEQ ID NO: 105, SEQ ID NO: 106 or SEQ ID NO: 107.

12. The isolated polypeptide according to a preceding claim wherein the p75NTR extracellular domain is truncated.

13. An isolated nucleic acid encoding the isolated polypeptide according to a preceding claim.

14. A vector comprising a nucleic acid according to claim 13.

15. A host cell comprising a nucleic acid according to claim 13 or a vector according to claim 14.

16. A fusion protein comprising a companion animal p75NTR extracellular domain, wherein said p75NTR comprises a variant amino acid at one or more of position 75, 109, 133 and/or 134, and a half-life extending moiety.

17. The fusion protein according to claim 16 wherein the half-life extending moiety is selected from an Fc domain, a serum albumin binder or PEG, optionally wherein the half-life extending moiety is a wild type or mutant Fc domain.

18. The fusion protein according to any of claims 16 to 217 wherein the half-life extending moiety is an Fc domain and the p75NTR extracellular domain or portion thereof and the Fc domain are linked with a linker, optionally wherein the linker is a peptide linker, further optionally the peptide linker is (GGGG)n or (G4S)n wherein n is 1 to 4.

19. The fusion protein according to any of claims 16 to 18 wherein the companion animal is a cat, dog, pig, cow, horse or camel.

20. The fusion protein according to any of claims 16 to 19 wherein the Fc domain is a canine Fc domain and the fusion protein comprises or consists of a sequence selected from SEQ ID NO: 47, SEQ ID NO: 50 SEQ ID NO: 53, SEQ ID NO: 56 or SEQ ID NO: 59; or wherein the Fc domain is a feline Fc domain and the fusion protein comprises or consists of a sequence selected from SEQ ID NO: 62, SEQ ID NO: 64, SEQ ID NO: 66, SEQ ID NO: 68 or SEQ ID NO: 70.

21. A nucleic acid encoding a fusion protein according to any of claims 16 to 20.

22. A vector comprising a nucleic acid according to claim 21.

23. A host cell comprising a nucleic acid according to claim 21 or a vector according to claim 22.

24. A pharmaceutical composition comprising an isolated polypeptide according to any of claims 1 to 12, or a fusion protein according to any of claims 16 to 20.

25. A method for treating an NGF-related disorder in a companion animal comprising administering an effective amount of the isolated companion animal p75NTR protein according to any of claims 1 to 12, a fusion protein according to any of claims 16 to 20 or a pharmaceutical composition of claim 24.

26. An isolated companion animal p75NTR protein according to any of claims 1 to 12, or a fusion protein according to any of claims 16 to 20, or a pharmaceutical composition of claim 24 for use in the treatment of one or more NGF-related disorders in a companion animal.

27. The method of claim 25 or the isolated companion animal p75NTR protein, fusion protein or pharmaceutical composition for use according to claim 26 wherein the one or more NGF-related disorders are cardiovascular diseases, atherosclerosis, obesity, type 2 diabetes, metabolic syndrome, pain and inflammation.

28. The method or the isolated companion animal p75NTR protein, fusion protein or pharmaceutical composition for use according to claim 27 wherein the NGF-related disorder is a pain related disorder, optionally wherein pain is selected from osteoarthritis pain, rheumatoid arthritis pain, surgical and postsurgical pain, incisional pain, general inflammatory pain, cancer pain, pain from trauma, neuropathic pain, neuralgia, diabetic neuropathy pain, pain associated with rheumatic diseases, pain associated with musculoskeletal diseases, visceral pain, and gastrointestinal pain.

29. The method or the isolated companion animal p75NTR protein, fusion protein or pharmaceutical composition for use according to claim 28 wherein the NGF-related disorder is inflammation, wherein the inflammation is an inflammatory disease, condition, or symptom, optionally wherein the inflammatory disease, condition, or symptom is selected from the group consisting of single or multiple organ failure or dysfunction, sepsis, cytokine storm, fever, neurological dysfunction or impairment, loss of taste or smell, cardiac dysfunction, pulmonary dysfunction, liver dysfunction, acute or chronic respiratory dysfunction, graft versus host disease (GVHD), cardiomyopathy, vasculitis, fibrosis, ophthalmic inflammation, dermatologic inflammation, gastrointestinal inflammation, tendinopathies, allergy, asthma, glomerulonephritis, pancreatitis, hepatitis, non-alcoholic steatohepatitis (NASH), inflammatory arthritis, gout, multiple sclerosis, psoriasis, acute respiratory distress syndrome (ARDS), diabetic ulcers, non-healing wounds, lupus, autoimmune diseases associated with acute or chronic inflammation, and acute or chronic inflammation associated with viral, bacterial or fungal infection, swelling, tenderness, joint stiffness or decrease in joint mobility.

30. A method of inhibiting NGF activity and/or pro-NGF activity in a companion animal comprising administering an isolated companion animal p75NTR protein according to any of claims 1 to 12, a fusion protein according to any of claims 16 to 20 or a pharmaceutical composition of claim 24.

31. The method or the isolated companion animal p75NTR protein, fusion protein or pharmaceutical composition for use according to claims 25 to 30 comprising administration of a second compound.

32. A kit comprising an isolated companion animal p75NTR protein according to any of claims 1 to 12, a fusion protein according to any of claims 16 to 20 or a pharmaceutical composition of claim 24 and optionally instructions for use.

33. A method for treating osteoarthritis in a companion animal comprising administering an effective amount of an isolated companion animal p75NTR protein or a portion thereof, or a pharmaceutical composition comprising said isolated companion animal p75NTR protein or a portion thereof.

34. An isolated companion animal p75NTR protein or a portion thereof, or a pharmaceutical composition comprising said isolated companion animal p75NTR protein or a portion thereof for use in the treatment of osteoarthritis in a companion animal.