Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K16/00—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K2317/00—Immunoglobulins specific features
  • C07K2317/10—Immunoglobulins specific features characterized by their source of isolation or production
  • C07K2317/14—Specific host cells or culture conditions, e.g. components, pH or temperature
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K2317/00—Immunoglobulins specific features
  • C07K2317/50—Immunoglobulins specific features characterized by immunoglobulin fragments
  • C07K2317/52—Constant or Fc region; Isotype

Definitions

• the invention relates generally to bovine antibody mutants and uses thereof. Specifically, the invention relates to one or more mutations in the Fc constant region of bovine antibody for improving various characteristics.
• Bovine IgG monoclonal antibodies can be effective therapeutics in veterinary medicine.
• mAbs can be effective therapeutics in veterinary medicine.
• three bovine IgG subclasses were identified.
• only limited work has been done to improve the characteristics of bovine IgGs.
• the neonatal Fc receptor prolongs the half-life of an IgG in a pH-dependent interaction with its fragment crystallizable (Fc) region.
• Fc fragment crystallizable
• the Fc region spanning the interface of CH2 and CH3 domains interacts with the FcRn on the surface of cells to regulate IgG homeostasis. This interaction is favored by an acidic interaction after IgG pinocytosis and thus IgG is protected from degradation.
• the endocytosed IgG is then recycled back to the cell surface and released into the blood stream at a slightly alkaline pH thereby maintaining sufficient serum IgG for proper function. Accordingly, the pharmacokinetic profile of IgGs depend on the structural and functional properties of their Fc regions.
• the invention relates to mutant bovine IgGs that exhibit desired characteristics, relative to wild-type bovine IgGs.
• the inventors of the instant application have found that substituting an amino acid residue at position 252, 286, 311, 312, 426, 428, 434, or 436 (numbered according to the Eu index as in Kabat) with another amino acid surprisingly and unexpectedly exhibited a desired effect.
• the unexpected desired effects include, but not limited to, enhanced affinity or reduced affinity to FcRn.
• the invention provides a modified IgG comprising: a bovine IgG constant domain comprising at least one amino acid substitution relative to a wild-type bovine IgG constant domain, wherein said substitution is at amino acid residue 252, 286, 311, 312, 426, 428, 434, or 436.
• the invention provides a polypeptide comprising: a bovine IgG constant domain comprising one or more amino acid substitutions of the invention described herein.
• the invention provides an antibody or a molecule comprising: a bovine IgG constant domain comprising one or more amino acid substitutions of the invention described herein.
• FIG. 3 shows protein modeling of Bovine IgG2a and IgG2b Fc regions.
• Figure 3 A Overlay of the protein models with a zoomed-in sub-panel showing amino acid residue positions are shown in ball-and-stick form.
• Figure 3B Root Mean Square Deviation (RMSD) comparisons of wild-type constructs of bovine IgG2a and IgG2b.
• RMSD Root Mean Square Deviation
• SEQ ID NO.: 8 refers to the amino acid sequence of IgG3b Wildtype.
• isolated when used in relation to a nucleic acid is a nucleic acid that is identified and separated from at least one contaminant nucleic acid with which it is ordinarily associated in its natural source. Isolated nucleic acid is in a form or setting different from that in which it is found in nature. Isolated nucleic acid molecules therefore are distinguished from the nucleic acid molecule as it exists in natural cells.
• An isolated nucleic acid molecule includes a nucleic acid molecule contained in cells that ordinarily express the polypeptide encoded therein where, for example, the nucleic acid molecule is in a plasmid or a chromosomal location different from that of natural cells.
• an antigen-specific antibody may be purified by complete or substantial removal (at least 90%, 91%, 92%, 93%, 94%, 95%, or more preferably at least 96%, 97%, 98% or 99%) of at least one contaminating non-immunoglobulin protein; it may also be purified by the removal of immunoglobulin protein that does not bind to the same antigen.
• the removal of non-immunoglobulin proteins and/or the removal of immunoglobulins that do not bind a particular antigen results in an increase in the percent of antigen-specific immunoglobulins in the sample.
• expression vector refers to a recombinant DNA molecule containing a desired coding sequence and appropriate nucleic acid sequences necessary for the expression of the operably linked coding sequence in a particular host organism.
• the term "host cell” refers to any eukaryotic or prokaryotic cell (e.g., bacterial cells such as E. coli, CHO cells, yeast cells, mammalian cells, avian cells, amphibian cells, plant cells, fish cells, and insect cells), whether located in vitro or in situ, or in vivo
• bacterial cells such as E. coli, CHO cells, yeast cells, mammalian cells, avian cells, amphibian cells, plant cells, fish cells, and insect cells
• the term "Fc region” refers to a C-terminal region of an immunoglobulin heavy chain.
• the "Fc region” may be a native sequence Fc region or a variant Fc region.
• the bovine IgG heavy chain Fc region is usually defined to stretch, for example, from the vertical lines to the c-terminus in Figure 1.
• variants comprise only portions of the Fc region and can include or not include the carboxy-terminus.
• the Fc region of an immunoglobulin generally comprises two constant domains, CH2 and CH3.
• variants having one or more of the constant domains are contemplated.
• variants without such constant domains are contemplated.
• the "CH2 domain" of a bovine IgG Fc region refers to, for example, the residues starting at the vertical lines and extending to residue 243 in Figure 1.
• the CH2 domain is unique in that it is not closely paired with another domain. Two N-linked branched carbohydrate chains are interposed between the two CH2 domains of an intact native IgG molecule.
• the "CH3 domain" of a bovine IgG Fc region generally is the stretch of residues C- terminal to a CH2 domain in an Fc region, for example, residues 244 to the c-terminus in Figure 1.
• a "functional Fc region” possesses an "effector function" of a native sequence Fc region.
• effector functions include, but are not limited to: Clq binding; complement dependent cytotoxicity (CDC); Fc receptor binding; antibody-dependent cell- mediated cytotoxicity (ADCC); antibody-dependent cellular phagocytosis (ADCP); down regulation of cell surface receptors (e.g., B cell receptor; BCR), etc.
• Such effector functions may require the Fc region to be operably linked to a binding domain (e.g., an antibody variable domain) and can be assessed using various assays (e.g., Fc binding assay, ADCC assays, CDC assays, ADCP assays, target cell depletion from whole or fractionated blood samples, etc.).
• a binding domain e.g., an antibody variable domain
• assays e.g., Fc binding assay, ADCC assays, CDC assays, ADCP assays, target cell depletion from whole or fractionated blood samples, etc.
• a “native sequence Fc region” or “wild type Fc region” refers to an amino acid sequence that is identical to the amino acid sequence of an Fc region commonly found in nature.
• Exemplary native sequence bovine Fc regions are from the vertical lines to the c-terminus in Figure 1.
• a “variant Fc region” comprises an amino acid sequence that differs from that of a native sequence Fc region (or fragment thereof) by virtue of at least one "amino acid substitution" as defined herein.
• the variant Fc region has at least one amino acid substitution compared to a native sequence Fc region or in the Fc region of a parent polypeptide, preferably 1, 2, 3, 4 or 5 amino acid substitutions in a native sequence Fc region or in the Fc region of the parent polypeptide.
• a variant Fc region may be generated according to the methods herein disclosed and this variant Fc region can be fused to a heterologous polypeptide of choice, such as an antibody variable domain or a nonantibody polypeptide, e.g., binding domain of a receptor or ligand.
• a heterologous polypeptide of choice such as an antibody variable domain or a nonantibody polypeptide, e.g., binding domain of a receptor or ligand.
• the term “derivative” in the context of polypeptides refers to a polypeptide that comprises and amino acid sequence which has been altered by introduction of an amino acid residue substitution.
• the term “derivative” as used herein also refers to a polypeptide which has been modified by the covalent attachment of any type of molecule to the polypeptide.
• an antibody may be modified, e.g., by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc.
• a derivative polypeptide may be produced by chemical modifications using techniques known to those of skill in the art, including, but not limited to specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. Further, a derivative polypeptide possesses a similar or identical function as the polypeptide from which it was derived. It is understood that a polypeptide comprising a variant Fc region of the present invention may be a derivative as defined herein, preferably the derivatization occurs within the Fc region.
• substantially of bovine origin indicates the polypeptide has an amino acid sequence at least 80%, at least 85%, more preferably at least 90%, 91%, 92%, 93%, 94% or even more preferably at least 95%, 96%, 97%, 98% or 99% homologous to that of a native bovine amino polypeptide.
• Fc receptor or “FcR” are used to describe a receptor that binds to an Fc region (e.g., the Fc region of an antibody).
• the preferred FcR is a native sequence FcR.
• a preferred FcR is one which binds an IgG antibody Fc region, an Fc gamma receptor or “FcgR”, and includes receptors of the Fc gamma RI (FcgRl), Fc gamma RII (FcgR2), Fc gamma RIII (FcgR3) subclasses, including allelic variants and alternatively spliced forms of these receptors as well as the novel bovine Fc gamma 2R (bFcg2R or bFcg?/ ).
• FcRn neonatal receptor
• FcRn neonatal receptor
• antibody-dependent cell-mediated cytotoxicity and "ADCC” refer to a cell-mediated reaction in which nonspecific cytotoxic cells (e.g., nonspecific) that express FcgRs (e.g., Natural Killer (“NK”) cells, neutrophils, and macrophages) recognize bound antibody on a target cell and subsequently cause lysis of the target cells.
• FcgRs e.g., Natural Killer (“NK") cells, neutrophils, and macrophages
• NK cells express FcgR3 only
• monocytes express FcgRl, FcgR2 and FcgR3.
• antibody-dependent cell-mediated phagocytosis and "ADCP” refer to a cell-mediated reaction in which phagocytic cells (e.g., macrophages, monocytes, dendritic cells) that express FcgRs (e.g., FcgRl, FcgR2a and FcgR3) recognize bound IgG antibody Fc region on a target cell and subsequently trigger a signaling cascade leading to the engulfment of the IgG-opsonized particle (e.g., bacteria, dead tissue cells).
• phagocytic cells e.g., macrophages, monocytes, dendritic cells
• FcgRs e.g., FcgRl, FcgR2a and FcgR3
• effector cells refers to leukocytes (preferably bovine) which express one or more FcRs and perform effector functions.
• the cells express at least FcgR3 and perform ADCC effector function.
• leukocytes which mediate ADCC include PBMC, NK cells, monocytes, macrophage, cytotoxic T cells and neutrophils.
• the effector cells may be isolated from a native source (e.g., from blood or PBMCs).
• the leukocytes express FcgRl, or other relevant Fc gamma receptor, and trigger ADCP function.
• a variant polypeptide with "altered” Fc receptor binding affinity is one which has either enhanced (i.e., increased, greater or higher) or diminished (i.e., reduced, decreased or lesser) Fc receptor binding affinity compared to the variant's parent polypeptide or to a polypeptide comprising a native Fc.
• a variant polypeptide which displays increased binding or increased binding affinity to an Fc receptor binds Fc receptor with greater affinity than the parent polypeptide.
• a variant polypeptide which displays decreased binding or decreased binding affinity to an Fc receptor binds Fc receptor with lower affinity than its parent polypeptide.
• variants which display decreased binding to an Fc receptor may possess little or no appreciable binding to an Fc receptor, e.g., 0-20% binding to Fc receptor the Fc receptor compared to a parent polypeptide.
• a variant polypeptide which binds an Fc receptor with "enhanced affinity" as compared to its parent polypeptide is one which binds Fc receptor with higher binding affinity than the parent polypeptide, when the amounts of variant polypeptide and parent polypeptide in a binding assay are essentially the same, and all other conditions are identical.
• a variant polypeptide with enhanced Fc receptor binding affinity may display from about 1.10 fold to about 100 fold (more typically from about 1.2 fold to about 50 fold) increase in Fc receptor binding affinity compared to the parent polypeptide, where Fc receptor binding affinity is determined, for example, in an ELISA assay or other method available to one of ordinary skill in the art.
• an “amino acid substitution” refers to the replacement of at least one existing amino acid residue in a given amino acid sequence with another different “replacement” amino acid residue.
• the replacement residue or residues may be "naturally occurring amino acid residues" (i.e., encoded by the genetic code) and selected from: alanine (Ala); arginine (Arg); asparagine (Asn); aspartic acid (Asp); cysteine (Cys); glutamine (Gin); glutamic acid (Glu); glycine (Gly); histidine (H is); isoleucine (He): leucine (Leu); lysine (Lys); methionine (Met); phenylalanine (Phe); proline (Pro); serine (Ser); threonine (Thr); tryptophan (Trp); tyrosine (Tyr); and valine (Vai).
• non-naturally occurring amino acid residue refers to a residue, other than those naturally occurring amino acid residues listed above, which is able to covalently bind adjacent amino acid residues (s) in a polypeptide chain.
• non-naturally occurring amino acid residues include norleucine, ornithine, norvaline, homoserine and other amino acid residue analogues such as those described in Ellman et al. Meth. Enzym. 202: 301-336 (1991).
• test signal refers to the output from any method of detecting proteinprotein interactions, including but not limited to, absorbance measurements from colorimetric assays, fluorescent intensity, or disintegrations per minute. Assay formats could include ELISA, FACS, or other methods. A change in the "assay signal” may reflect a change in cell viability and/or a change in the kinetic off-rate, the kinetic on-rate, or both.
• a “higher assay signal” refers to the measured output number being larger than another number (e.g., a variant may have a higher (larger) measured number in an ELISA assay as compared to the parent polypeptide).
• a “lower” assay signal refers to the measured output number being smaller than another number (e.g., a variant may have a lower (smaller) measured number in an ELISA assay as compared to the parent polypeptide).
• binding affinity refers to the equilibrium dissociation constant (expressed in units of concentration) associated with each Fc receptor-Fc binding interaction.
• the binding affinity is directly related to the ratio of the kinetic off-rate (generally reported in units of inverse time, e.g., seconds' 1 ) divided by the kinetic on-rate (generally reported in units of concentration per unit time, e.g., molar/second).
• KD equilibrium dissociation constant
• Hinge region refers to the stretch of amino acids that links the Fab antigen binding region to the Fc region of an antibody. Hinge regions of IgG subclasses may be aligned by placing the first and last cysteine residues forming inter-heavy chain disulfide (S — S) bonds in the same positions. As shown in Figure 1, the hinge region, for example, in bovine IgG constant region starts at residue 99 and extends to the vertical lines.
• Clq is a polypeptide that includes a binding site for the Fc region of an immunoglobulin. Clq together with two serine proteases, Cir and Cis, forms the complex Cl, the first component of the CDC pathway.
• antibody is used interchangeably with “immunoglobulin” or “Ig,” is used in the broadest sense and specifically covers monoclonal antibodies (including full length monoclonal antibodies), polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies), and antibody fragments so long as they exhibit the desired biological activity or functional activity.
• monoclonal antibodies including full length monoclonal antibodies
• polyclonal antibodies polyclonal antibodies
• multispecific antibodies e.g., bispecific antibodies
• antibody fragments so long as they exhibit the desired biological activity or functional activity.
• Single chain antibodies, and chimeric, bovine, or bovinized antibodies, as well as chimeric or CDR-grafted single chain antibodies, and the like, comprising portions derived from different species, are also encompassed by the present invention and the term "antibody”.
• the various portions of these antibodies can be joined together chemically by conventional techniques, synthetically, or can be prepared as a contiguous protein using genetic engineering techniques.
• nucleic acids encoding a chimeric or bovinized chain can be expressed to produce a contiguous protein. See, e.g., U.S. Pat. No. 4,816,567; U.S. Pat. No. 4,816,397; WO 86/01533; U.S. Pat. No. 5,225,539; and U.S. Pat. Nos. 5,585,089 and 5,698,762. See also, Newman, R. et al.
• the antibodies comprising an Fc region (or portion thereof) are encompassed herein within the term "antibody.”
• the antibody may be labeled with a detectable label, immobilized on a solid phase and/or conjugated with a heterologous compound (e.g., an enzyme or toxin) according to methods known in the art.
• a heterologous compound e.g., an enzyme or toxin
• antibody fragments refers to a portion of an intact antibody.
• antibody fragments include, but are not limited to, linear antibodies; single-chain antibody molecules; Fc or Fc' peptides, Fab and Fab fragments, and multispecific antibodies formed from antibody fragments.
• the antibody fragments preferably retain at least part of the hinge and optionally the CHI region of an IgG heavy chain.
• the antibody fragments comprise at least a portion of the CH2 region or the entire CH2 region.
• the term "functional fragment”, when used in reference to a monoclonal antibody, is intended to refer to a portion of the monoclonal antibody that still retains a functional activity.
• a functional activity can be, for example, antigen binding activity or specificity, receptor binding activity or specificity, effector function activity and the like.
• Monoclonal antibody functional fragments include, for example, individual heavy or light chains and fragments thereof, such as VL, VH and Fd; monovalent fragments, such as Fv, Fab, and Fab'; bivalent fragments such as F(ab')2; single chain Fv (scFv); and Fc fragments.
• fragment refers to a polypeptide comprising an amino acid sequence of at least 5, 15, 20, 25, 40, 50, 70, 90, 100 or more contiguous amino acid residues of the amino acid sequence of another polypeptide.
• a fragment of a polypeptide retains at least one function of the full-length polypeptide.
• chimeric antibody includes monovalent, divalent or polyvalent immunoglobulins.
• a monovalent chimeric antibody is a dimer formed by a chimeric heavy chain associated through disulfide bridges with a chimeric light chain.
• a divalent chimeric antibody is a tetramer formed by two heavy chain-light chain dimers associated through at least one disulfide bridge.
• a chimeric heavy chain of an antibody for use in bovine comprises an antigen-binding region derived from the heavy chain of a non-bovine antibody, which is linked to at least a portion of a bovine heavy chain constant region, such as CHI or CH2.
• a chimeric light chain of an antibody for use in bovine comprises an antigen binding region derived from the light chain of a non-bovine antibody, linked to at least a portion of a bovine light chain constant region (CL).
• Antibodies, fragments or derivatives having chimeric heavy chains and light chains of the same or different variable region binding specificity can also be prepared by appropriate association of the individual polypeptide chains, according to known method steps. With this approach, hosts expressing chimeric heavy chains are separately cultured from hosts expressing chimeric light chains, and the immunoglobulin chains are separately recovered and then associated.
• the hosts can be co-cultured and the chains allowed to associate spontaneously in the culture medium, followed by recovery of the assembled immunoglobulin or fragment or both the heavy and light chains can be expressed in the same host cell.
• Methods for producing chimeric antibodies are well known in the art (see, e.g., U.S. Pat. Nos. 6,284,471; 5,807,715; 4,816,567; and 4,816,397).
• bovinized forms of non-bovine (e.g., murine) antibodies are antibodies that contain minimal sequence, or no sequence, derived from non-bovine immunoglobulin.
• bovinized antibodies are bovine immunoglobulins (recipient antibody) in which residues from a hypervariable region of the recipient are replaced by residues from a hypervariable region of a non-bovine species (donor antibody) such as mouse, rat, rabbit, human or nonhuman primate having the desired specificity, affinity, and capacity.
• donor antibody such as mouse, rat, rabbit, human or nonhuman primate having the desired specificity, affinity, and capacity.
• framework region (FR) residues of the bovine immunoglobulin are replaced by corresponding non-bovine residues.
• bovinized antibodies may comprise residues that are not found in the recipient antibody or in the donor antibody. These modifications are generally made to further refine antibody performance.
• the bovinized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the hypervariable loops (CDRs) correspond to those of a non-bovine immunoglobulin and all or substantially all of the FR residues are those of a bovine immunoglobulin sequence.
• the bovinized antibody may also comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a bovine immunoglobulin.
• Fc immunoglobulin constant region
• immunoadhesin designates antibody-like molecules which combine the binding domain of a heterologous "adhesin” protein (e.g., a receptor, ligand or enzyme) with an immunoglobulin constant domain.
• immunoadhesins comprise a fusion of the adhesin amino acid sequence with the desired binding specificity which is other than the antigen recognition and binding site (antigen combining site) of an antibody (i.e., is "heterologous”) with an immunoglobulin constant domain sequence.
• ligand binding domain refers to any native receptor or any region or derivative thereof retaining at least a qualitative ligand binding ability of a corresponding native receptor.
• the receptor is from a cell-surface polypeptide having an extracellular domain that is homologous to a member of the immunoglobulin supergene family.
• receptors which are not members of the immunoglobulin supergene family but are nonetheless specifically covered by this definition, are receptors for cytokines, and in particular receptors with tyrosine kinase activity (receptor tyrosine kinases), members of the hematopoietin and nerve growth factor receptor superfamilies, and cell adhesion molecules (e.g., E-, L-, and P-selectins).
• receptor binding domain refers to any native ligand for a receptor, including, e.g., cell adhesion molecules, or any region or derivative of such native ligand retaining at least a qualitative receptor binding ability of a corresponding native ligand.
• an "isolated" polypeptide is one that has been identified and separated and/or recovered from a component of its natural environment. Contaminant components of its natural environment are materials that would interfere with diagnostic or therapeutic uses for the polypeptide, and may include enzymes, hormones, and other proteinaceous or non- proteinaceous solutes.
• the isolated polypeptide is purified (1) to greater than 95% by weight of polypeptides as determined by the Lowry method, and preferably, more than 99% by weight, (2) to a degree sufficient to obtain at least 15 residues of N-terminal or internal amino acid sequence by use of a spinning cup sequenator, or (3) to homogeneity by SDS-page under reducing or nonreducing conditions using Coomassie blue or silver stain.
• Isolated polypeptide includes the polypeptide in situ within recombinant cells since at least one component of the polypeptide's natural environment will not be present. Ordinarily, however, isolated polypeptide will be prepared by a least one purification step.
• disorders and “disease” are used interchangeably to refer to any condition that would benefit from treatment with a variant polypeptide (a polypeptide comprising a variant Fc region of the invention), including chronic and acute disorders or diseases (e.g., pathological conditions that predispose a patient to a particular disorder).
• diseases e.g., pathological conditions that predispose a patient to a particular disorder.
• the term "receptor” refers to a polypeptide capable of binding at least one ligand.
• the preferred receptor is a cell-surface or soluble receptor having an extracellular ligand-binding domain and, optionally, other domains (e.g., transmembrane domain, intracellular domain and/or membrane anchor).
• a receptor to be evaluated in an assay described herein may be an intact receptor or a fragment or derivative thereof (e.g. a fusion protein comprising the binding domain of the receptor fused to one or more heterologous polypeptides).
• the receptor to be evaluated for its binding properties may be present in a cell or isolated and optionally coated on an assay plate or some other solid phase or labeled directly and used as a probe.
• a variant polypeptide that knocks out, or knocks down, antibodydependent cell-mediated cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP) and complement-dependent cytotoxicity (CDC) in the presence of bovine effector cells compared to parent antibody is one which in vitro or in vivo is substantially less active at mediating ADCC, ADCP and/or CDC, when the amounts of variant polypeptide and parent antibody used in the assay are essentially the same.
• ADCC antibodydependent cell-mediated cytotoxicity
• ADCP antibody-dependent cellular phagocytosis
• CDC complement-dependent cytotoxicity
• variants may be identified, for example, using an ADCC, ADCP or CDC assay, but other assays or methods for determining ADCC, ADCP or CDC activity may also be employed (e.g., animal models).
• the variant polypeptide is about 100, 75, 50, or 25 percent less active at mediating ADCC, ADCP and CDC than the parent polypeptide.
• Bovine IgGs are well known in the art and fully described in, for example, Symons et al., 19 9, Mol. ImmunoL, vol. 26(9), pages 841-850; Kacskovics et al., 1996, Mol. Immunol., vol. 33(2), pages 189-195; Saini et al., 2007, Scand. J. Immunol., vol. 65(1), pages 32-38; and Rabbani et al., 1997, Immunogenetics, vol. 46(4), pages 326-331.
• bovine IgG is IgGl. In another embodiment, bovine IgG is IgG2. In yet another embodiment, bovine IgG is IgG3. In one example, IgGl is IgGl a, IgGlb, IgGlc, or IgGld. In another example, IgG2 is IgG2a or IgG2b. In yet another example, IgG3 is IgG3a or IgG3b.
• amino acid and nucleic acid sequences of IgGla, IgGlb, IgGlc, IgGld, IgG2a, IgG2b, IgG3a, and IgG3b are also well known in the art.
• IgG of the invention comprises a constant domain, for example, CHI, CH2, or CH3 domains, or a combination thereof.
• the constant domain of the invention comprises Fc region, including, for example, CH2 or CH3 domains or a combination thereof.
• the wild-type constant domain comprises any one of the amino acid sequences set forth in SEQ ID NOs.: 1-8.
• the wild-type constant domain of IgGla, IgGlb, IgGlc, IgGld, IgG2a, IgG2b, IgG3a, and IgG3b comprises the amino acid sequence set forth in SEQ ID NO.: 1, 2, 3, 4, 5, 6, 7, and 8, respectively.
• the wild-type IgG constant domain is a homologue, a variant, an isomer, or a functional fragment of any one of SEQ ID NOs.: 1-8, but without any mutation described herein.
• the wild-type constant domain of IgG2a comprises the amino acid sequence set forth in SEQ ID NO.: 9.
• IgGs contant domains also include polypeptides with amino acid sequences substantially similar to the amino acid sequence of the heavy and/or light chain. Substantially the same amino acid sequence is defined herein as a sequence with at least 70%, 75%, 80%, 85%, 90%, 95%, or 99% identity to a compared amino acid sequence, as determined by the FASTA search method in accordance with Pearson and Lipman, Proc. Natl. Acad. Sci. USA 85:2444-2448 (1988).
• the present invention also includes nucleic acid molecules that encode IgGs or portion thereof, described herein.
• the nucleic acids may encode an antibody heavy chain comprising, for example, CHI, CH2, CH3 regions, or a combination thereof.
• the nucleic acids may encode an antibody heavy chain comprising, for example, any one of the VH regions or a portion thereof, or any one of the VH CDRs, including any variants thereof.
• the invention also includes nucleic acid molecules that encode an antibody light chain comprising, for example, any one of the CL regions or a portion thereof, any one of the VL regions or a portion thereof or any one of the VL CDRs, including any variants thereof.
• the nucleic acid encodes both a heavy and light chain, or portions thereof.
• amino acid sequence of the wild-type constant domain set forth in SEQ ID NO.: 1, 2, 3, 4, 5, 6, 7, 8, or 9 is encoded by its corresponding nucleic acid sequence.
• position refers to a position numbered according to the Eu index as in Kabat (Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Sendee, National Institutes of Health, Bethesda, Md. (1991)).
• the desired effect is a higher affinity to FcRn, relative to an IgG having the wild-type bovine IgG constant domain.
• the desired effect is eliminating or reducing complement-dependent cytotoxicity, relative to an IgG having the wild-type bovine IgG constant domain. In another embodiment, the desired effect is eliminating or reducing antibody-dependent cellular phagocytosis, relative to an IgG having the wild-type bovine IgG constant domain. In yet another embodiment, the desired effect is eliminating or reducing the binding of the IgG to Fc gamma receptor (bFcgR).
• bFcgR Fc gamma receptor
• substitution amino acid includes, for example, but not limited to, asparagine, histidine, serine, alanine, phenylalanine, glycine, isoleucine, lysine, leucine, methionine, glutamine, arginine, threonine, valine, tryptophan, tyrosine, cysteine, aspartic acid, glutamic acid, and proline.
• the substitution amino acid is a non-natural amino acid.
• the modified bovine IgG of the invention can be any suitable bovine IgG, known to one of skilled in the art.
• the bovine IgG2 constant domain comprises one or more of substitution mutations M252A, M252C, M252D, M252E, M252F, M252G, M252H, M252I, M252K, M252L, M252N, M252P, M252Q, M252R, M252S, M252T, M252V, M252W, M252Y, T286A, T286C, T286D, T286E, T286F, T286G, T286H, T286I, T286K, T286L, T286M, T286N, T286P, T286Q, T286R, T286S, T286V, T286W, T286Y, Q311A, Q311C, Q311D, Q311E, Q311F, Q311G, Q311H, Q311H, Q31111, Q3
• the mutant IgG2 constant domain of the invention comprises one or more mutations described herein.
• the mutant IgG2 constant domain is a homologue, a variant, an isomer, or a functional fragment, but with mutation of the invention described herein. Each possibility represents a separate embodiment of the present invention.
• the CDRs represent non-contiguous stretches of amino acids within the variable regions but, regardless of species, the positional locations of these critical amino acid sequences within the variable heavy and light chain regions have been found to have similar locations within the amino acid sequences of the variable chains.
• the variable heavy and light chains of all antibodies each have three CDR regions, each non-contiguous with the others.
• antibody peptides contain constant (i.e., highly conserved) and variable regions, and, within the latter, there are the CDRs and the so-called "framework regions" made up of amino acid sequences within the variable region of the heavy or light chain but outside the CDRs.
• the antibody coding regions for use in the present invention could also be provided by altering existing antibody genes using standard molecular biological techniques that result in variants of the antibodies and peptides described herein. Such variants include, but are not limited to deletions, additions and substitutions in the amino acid sequence of the antibodies or peptides.
• Variant bovine antibodies or peptides may be fully functional or may lack function in one or more activities.
• Fully functional variants typically contain only conservative variations or variations in non-critical residues or in non-critical regions.
• Functional variants can also contain substitution of similar amino acids that result in no change or an insignificant change in function. Alternatively, such substitutions may positively or negatively affect function to some degree.
• Non-functional variants typically contain one or more non-conservative amino acid substitutions, deletions, insertions, inversions, or truncation or a substitution, insertion, inversion, or deletion in a critical residue or critical region.
• polypeptides often contain amino acids other than the twenty "naturally occurring" amino acids.
• amino acids including the terminal amino acids, may be modified by natural processes, such as processing and other post-translational modifications, or by chemical modification techniques well known in the art.
• Derivatives also include radioactively labeled monoclonal antibodies that are labeled.
• radioactive iodine (251,1311), carbon (4C), sulfur (35S), indium, tritium (H 3 ) or the like
• conjugates of monoclonal antibodies with biotin or avidin with enzymes, such as horseradish peroxidase, alkaline phosphatase, beta-D-galactosidase, glucose oxidase, glucoamylase, carboxylic acid anhydrase, acetylcholine esterase, lysozyme, malate dehydrogenase or glucose 6-phosphate dehydrogenase
• bioluminescent agents such as luciferase
• chemoluminescent agents such as acridine esters
• fluorescent agents such as phycobiliproteins
• a nucleic acid sequence encoding at least one antibody, portion or polypeptide of the invention may be recombined with vector DNA in accordance with conventional techniques, including blunt-ended or staggered-ended termini for ligation, restriction enzyme digestion to provide appropriate termini, filling in of cohesive ends as appropriate, alkaline phosphatase treatment to avoid undesirable joining, and ligation with appropriate ligases. Techniques for such manipulations are disclosed, e.g., by Maniatis et al., MOLECULAR CLONING, LAB. MANUAL, (Cold Spring Harbor Lab. Press, NY, 1982 and 1989), and Ausubel et al. 1993 supra, may be used to construct nucleic acid sequences which encode an antibody molecule or antigen binding region thereof.
• a nucleic acid molecule such as DNA
• An operable linkage is a linkage in which the regulatory DNA sequences and the DNA sequence sought to be expressed are connected in such a way as to permit gene expression as peptides or antibody portions in recoverable amounts.
• the precise nature of the regulatory regions needed for gene expression may vary from organism to organism, as is well known in the analogous art. See, e.g., Sambrook etal., 2001 supra; Ausubel et a!.. 1993 supra.
• Example prokaryotic vectors known in the art include plasmids such as those capable of replication in A. coll (such as, for example, pBR322, CoIEl, pSClOl, pACYC 184, .pi.vX). Such plasmids are, for example, disclosed by Maniatis et al., 1989 supra; Ausubel et al, 1993 supra. Bacillus plasmids include pC194, pC221, pT127, etc. Such plasmids are disclosed by Gryczan, in THE MOLEC. BIO. OF THE BACILLI 307-329 (Academic Press, NY, 1982).
• Suitable Streptomyces plasmids include plJlOl (Kendall et al., 169 J. Bacteriol. 4177-83 (1987), and Streptomyces bacteriophages such as phLC31 (Chater et al., in SIXTH INT'L SYMPOSIUM ON ACTINOMYCETALES BIO. 45-54 (Akademiai Kaido, Budapest, Hungary 1986). Pseudomonas plasmids are reviewed in John et al., 8 Rev. Infect. Dis. 693-704 (1986); Izaki, 33 Jpn. J. Bacteriol. 729-42 (1978); and Ausubel et al., 1993 supra.
• gene expression elements useful for the expression of cDNA encoding antibodies or peptides include, but are not limited to, (a) viral transcription promoters and their enhancer elements, such as the SV40 early promoter (Okayama et al., 3 Mol. Cell. Biol. 280 (1983), Rous sarcoma virus LTR (Gorman et al., 79 Proc. Natl. Acad.
• Immunoglobulin cDNA genes can be expressed as described by Weidle et al., 51 Gene 21 (1987), using as expression elements the SV40 early promoter and its enhancer, the mouse immunoglobulin H chain promoter enhancers, SV40 late region mRNA splicing, rabbit S-globin intervening sequence, immunoglobulin and rabbit S-globin polyadenylation sites, and SV40 polyadenylation elements.
• immunoglobulin genes comprised of part cDNA, part genomic DNA (Whittle et al., 1 Protein Engin.
• the transcriptional promoter can be human cytomegalovirus
• the promoter enhancers can be cytomegalovirus and mouse/human immunoglobulin
• mRNA splicing and polyadenylation regions can be the native chromosomal immunoglobulin sequences.
• the transcriptional promoter is a viral LTR sequence
• the transcriptional promoter enhancers are either or both the mouse immunoglobulin heavy chain enhancer and the viral LTR enhancer
• the splice region contains an intron of greater than 31 bp
• the polyadenylation and transcription termination regions are derived from the native chromosomal sequence corresponding to the immunoglobulin chain being synthesized.
• cDNA sequences encoding other proteins are combined with the above-recited expression elements to achieve expression of the proteins in mammalian cells.
• Each fused gene can be assembled in, or inserted into, an expression vector.
• Recipient cells capable of expressing the immunoglobulin chain gene product are then transfected singly with a peptide or H or L chain-encoding gene, or are co-transfected with H and L chain gene.
• the transfected recipient cells are cultured under conditions that permit expression of the incorporated genes and the expressed immunoglobulin chains or intact antibodies or fragments are recovered from the culture.
• the fused genes encoding the peptide or H and L chains, or portions thereof are assembled in separate expression vectors that are then used to cotransfect a recipient cell.
• the fused genes encoding the H and L chains can be assembled on the same expression vector.
• the recipient cell line may be a myeloma cell.
• Myeloma cells can synthesize, assemble and secrete immunoglobulins encoded by transfected immunoglobulin genes and possess the mechanism for glycosylation of the immunoglobulin.
• Myeloma cells can be grown in culture or in the peritoneal cavity of a mouse, where secreted immunoglobulin can be obtained from ascites fluid.
• lymphoid cells such as B lymphocytes of bovine or non-bovine origin, hybridoma cells of bovine or non-bovine origin, or interspecies heterohybridoma cells.
• the expression vector carrying an antibody construct or polypeptide of the invention can be introduced into an appropriate host cell by any of a variety of suitable means, including such biochemical means as transformation, transfection, conjugation, protoplast fusion, calcium phosphate-precipitation, and application with polycations such as diethylaminoethyl (DEAE) dextran, and such mechanical means as electroporation, direct microinjection, and microprojectile bombardment. Johnston et a!.. 240 Science 1538 (1988).
• DEAE diethylaminoethyl
• Yeast may provide substantial advantages over bacteria for the production of immunoglobulin H and L chains. Yeasts carry out post-translational peptide modifications including glycosylation. A number of recombinant DNA strategies now exist which utilize strong promoter sequences and high copy number plasmids which can be used for production of the desired proteins in yeast. Yeast recognizes leader sequences of cloned mammalian gene products and secretes peptides bearing leader sequences (i.e., pre-peptides). Hitzman et al., 11th Int'l Conference on Yeast, Genetics & Molec. Biol. (Montpelier, France, 1982).
• Yeast gene expression systems can be routinely evaluated for the levels of production, secretion and the stability of peptides, antibodies, fragments and regions thereof. Any of a series of yeast gene expression systems incorporating promoter and termination elements from the actively expressed genes coding for glycolytic enzymes produced in large quantities when yeasts are grown in media rich in glucose can be utilized. Known glycolytic genes can also provide very efficient transcription control signals. For example, the promoter and terminator signals of the phosphoglycerate kinase (PGK) gene can be utilized. A number of approaches can be taken for evaluating optimal expression plasmids for the expression of cloned immunoglobulin cDNAs in yeast. See Vol. II DNA Cloning, 45-66, (Glover, ed.,) IRL Press, Oxford, UK 1985).
• Bacterial strains can also be utilized as hosts for the production of antibody molecules or peptides described by this invention.
• Plasmid vectors containing replicon and control sequences which are derived from species compatible with a host cell are used in connection with these bacterial hosts.
• the vector carries a replication site, as well as specific genes which are capable of providing phenotypic selection in transformed cells.
• a number of approaches can be taken for evaluating the expression plasmids for the production of antibodies, fragments and regions or antibody chains encoded by the cloned immunoglobulin cDNAs in bacteria (see Glover, 1985 supra; Ausubel, 1993 supra; Sambrook, 2001 supra; Colligan et al., eds.
• Host mammalian cells may be grown in vitro or in vivo. Mammalian cells provide posttranslational modifications to immunoglobulin protein molecules including leader peptide removal, folding and assembly of Hand L chains, glycosylation of the antibody molecules, and secretion of functional antibody protein.
• Mammalian cells which can be useful as hosts for the production of antibody proteins include cells of fibroblast origin, such as Vero (ATCC CRL 81) or CHO-K1 (ATCC CRL 61) cells.
• fibroblast origin such as Vero (ATCC CRL 81) or CHO-K1 (ATCC CRL 61) cells.
• Many vector systems are available for the expression of cloned peptides Hand L chain genes in mammalian cells (see Glover, 1985 supra). Different approaches can be followed to obtain complete H2L2 antibodies. It is possible to co-express Hand L chains in the same cells to achieve intracellular association and linkage of Hand L chains into complete tetrameric H2L2 antibodies and/or peptides. The co-expression can occur by using either the same or different plasmids in the same host.
• Genes for both Hand L chains and/or peptides can be placed into the same plasmid, which is then transfected into cells, thereby selecting directly for cells that express both chains.
• cells can be transfected first with a plasmid encoding one chain, for example the L chain, followed by transfection of the resulting cell line with an H chain plasmid containing a second selectable marker, cell lines producing peptides and/or H2L2 molecules via either route could be transfected with plasmids encoding additional copies of peptides, H, L, or H plus L chains in conjunction with additional selectable markers to generate cell lines with enhanced properties, such as higher production of assembled H2L2 antibody molecules or enhanced stability of the transfected cell lines.
• stable expression may be used.
• cell lines which stably express the antibody molecule may be engineered. Rather than using expression vectors which contain viral origins of replication, host cells can be transformed with immunoglobulin expression cassettes and a selectable marker. Following the introduction of the foreign DNA, engineered cells may be allowed to grow for 1-2 days in enriched media, and then are switched to a selective media.
• the selectable marker in the recombinant plasmid confers resistance to the selection and allows cells to stably integrate the plasmid into a chromosome and grow to form foci which in turn can be cloned and expanded into cell lines.
• Such engineered cell lines may be particularly useful in screening and evaluation of compounds/components that interact directly or indirectly with the antibody molecule.
• an antibody of the invention may be purified by any method known in the art for purification of an immunoglobulin molecule, for example, by chromatography (e.g., ion exchange, affinity, particularly affinity for the specific antigen after Protein A, and sizing column chromatography), centrifugation, differential solubility, or by any other standard technique for the purification of proteins.
• chromatography e.g., ion exchange, affinity, particularly affinity for the specific antigen after Protein A, and sizing column chromatography
• centrifugation e.g., centrifugation, differential solubility, or by any other standard technique for the purification of proteins.
• antibodies are secreted from the cell into culture medium and harvested from the culture medium.
• the invention also provides a pharmaceutical composition comprising molecules of the invention and one or more pharmaceutically acceptable carriers. More specifically, the invention provides for a pharmaceutical composition comprising a pharmaceutically acceptable carrier or diluent and, as active ingredient, an antibody or peptide according to the invention.
• “Pharmaceutically acceptable carriers” include any excipient which is nontoxic to the cell or animal being exposed thereto at the dosages and concentrations employed.
• the pharmaceutical composition may include one or additional therapeutic agents.
• “Pharmaceutically acceptable” refers to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for contact with the tissues of animals without excessive toxicity, irritation, allergic response, or other problem complications commensurate with a reasonable benefit/risk ratio.
• Pharmaceutically acceptable carriers include solvents, dispersion media, buffers, coatings, antibacterial and antifungal agents, wetting agents, preservatives, buggers, chelating agents, antioxidants, isotonic agents and absorption delaying agents.
• Pharmaceutically acceptable carriers include water; saline; phosphate buffered saline; dextrose; glycerol; alcohols such as ethanol and isopropanol; phosphate, citrate and other organic acids; ascorbic acid; low molecular weight (less than about 10 residues) polypeptides; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, arginine or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; EDTA; salt forming counterions such as sodium; and/or nonionic surfactants such as TWEEN, polyethylene glycol (PEG), and PLURONICS; isotonic agents such as sugars, polyalcohols such as mannitol and sorbitol, and sodium chloride; as well as combinations
• compositions of the invention can be administered either as individual therapeutic agents or in combination with other therapeutic agents. They can be administered alone, but are generally administered with a pharmaceutical carrier selected on the basis of the chosen route of administration and standard pharmaceutical practice.
• Administration of the antibodies disclosed herein may be carried out by any suitable means, including parenteral injection (such as intraperitoneal, subcutaneous, or intramuscular injection), orally, or by topical administration of the antibodies (typically carried in a pharmaceutical formulation) to an airway surface.
• Topical administration to an airway surface can be carried out by intranasal administration (e.g., by use of dropper, swab, or inhaler).
• Topical administration of the antibodies to an airway surface can also be carried out by inhalation administration, such as by creating respirable particles of a pharmaceutical formulation (including both solid and liquid particles) containing the antibodies as an aerosol suspension, and then causing the subject to inhale the respirable particles.
• respirable particles of a pharmaceutical formulation including both solid and liquid particles
• Methods and apparatus for administering respirable particles of pharmaceutical formulations are well known, and any conventional technique can be employed.
• the antibodies are administered by parenteral inj ection.
• parenteral administration antibodies or molecules can be formulated as a solution, suspension, emulsion or lyophilized powder in association with a pharmaceutically acceptable parenteral vehicle.
• the vehicle may be a solution of the antibody or a cocktail thereof dissolved in an acceptable carrier, such as an aqueous carrier such vehicles are water, saline, Ringer's solution, dextrose solution, trehalose or sucrose solution, or 5% serum albumin, 0.4% saline, 0.3% glycine and the like.
• liposomes and nonaqueous vehicles such as fixed oils can also be used. These solutions are sterile and generally free of particulate matter.
• the vehicle or lyophilized powder can contain additives that maintain isotonicity (e.g., sodium chloride, mannitol) and chemical stability (e.g., buffers and preservatives).
• the formulation is sterilized by commonly used techniques. Actual methods for preparing parenterally administrable compositions will be known or apparent to those skilled in the art and are described in more detail in, for example, REMINGTON'S PHARMA. SCI. (15th ed., Mack Pub. Co., Easton, Pa., 1980).
• the antibodies or molecules of the invention can be lyophilized for storage and reconstituted in a suitable carrier prior to use. This technique has been shown to be effective with conventional immune globulins. Any suitable lyophilization and reconstitution techniques can be employed. It will be appreciated by those skilled in the art that lyophilization and reconstitution can lead to varying degrees of antibody activity loss and that use levels may have to be adjusted to compensate.
• the compositions containing the present antibodies or a cocktail thereof can be administered for prevention of recurrence and/or therapeutic treatments for existing disease. Suitable pharmaceutical carriers are described in the most recent edition of REMINGTON'S PHARMACEUTICAL SCIENCES, a standard reference text in this field of art. In therapeutic application, compositions are administered to a subject already suffering from a disease, in an amount sufficient to cure or at least partially arrest or alleviate the disease and its complications.
• Effective doses of the compositions of the present invention, for treatment of conditions or diseases as described herein vary depending upon many different factors, including, for example, but not limited to, the pharmacodynamic characteristics of the particular agent, and its mode and route of administration; target site; physiological state of the animal; other medications administered; whether treatment is prophylactic or therapeutic; age, health, and weight of the recipient; nature and extent of symptoms kind of concurrent treatment, frequency of treatment, and the effect desired.
• compositions can be carried out with dose levels and pattern being selected by the treating veterinarian.
• pharmaceutical formulations should provide a quantity of the antibody(ies) of this invention sufficient to effectively treat the subject.
• Treatment dosages may be titrated using routine methods known to those of skill in the art to optimize safety and efficacy.
• compositions of the invention may include a “therapeutically effective amount.”
• a “therapeutically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired therapeutic result.
• a therapeutically effective amount of a molecule may vary according to factors such as the disease state, age, sex, and weight of the individual, and the ability of the molecule to elicit a desired response in the individual.
• a therapeutically effective amount is also one in which any toxic or detrimental effects of the molecule are outweighed by the therapeutically beneficial effects.
• Beneficial or desired clinical results include, but are not limited to, alleviation of symptoms, diminishment of the extent of a disease or condition, stabilization of a disease or condition (i.e., where the disease or condition does not worsen), delay or slowing of the progression of a disease or condition, amelioration or palliation of the disease or condition, and remission (whether partial or total) of the disease or condition, whether detectable or undetectable.
• Those in need of treatment include those already with the disease or condition as well as those prone to having the disease or condition or those in which the disease or condition is to be prevented.
• EXPICHO-S Choinese Hamster Ovary cells
• EXPICHO-S cells were maintained in EXPICHO expression medium (Gibco) between 0.14 and 8.0xl0e6 cells/ml.
• Cells were diluted following the ExpiCHO Protocol user manual on Day -1 and transfection day. Diluted cells were transfected as described in the protocol using reagents sourced from ExpiFectamine CHO Transfection Kit (Gibco) following Max Titer conditions. Following 12-14 days of incubation, the cultures were harvested and clarified.
• Antibodies were purified from the clarified supernatant via Protein A chromatography over Mab Select Sure LX (GE Healthcare) which had been pre-equilibrated with PBS. Following sample load, the resin was washed with PBS and then with 20 mM sodium acetate, pH 5.5. Samples were eluted from the column with 20 mM acetic acid, pH 3.5. Following elution, pools were made and neutralized with the addition of 1 M sodium acetate to 4%. Depending on available volume and intended use, samples were sometimes exchanged into a final buffer (e.g. PBS, other). Concentration was measured by absorbance at 280 nm.
• PBS final buffer
• Non-reduced (nr) and reduced sodium dodecyl sulfate polyacrylamide electrophoresis (SDS-PAGE) was performed using 4-12% Bis-Tris NuPAGE gels in MES- SDS running buffer, and SeeBlue Plus 2 standards, all from Invitrogen.
• NEM alkylating agent N-ethylmaleimide
• DTT dithiothreitol
• Bovine Fc-based antibodies or fusion protein binding affinities to bovine FcRn were determined by surface plasmon resonance (SPR). All reported KD's were measured in Biacore T200 (Cytiva, Marlborough, MA, USA) or Biacore 8K (Cytiva, Marlborough, MA, USA) using SA sensor. Bovine FcRn was captured on the surface of the sensor for a desired surface density. Running buffer of 20 mM MES, 150 mM NaCl, 0.005% Tween 20, 0.5 mg/mL BSA, pH 6 and/or PBS, 0.0005% Tween 20, pH7.4 were used.
• the Fc regions of the two bovine allotypes, IgG2a and IgG2b were first designed using their respective CH2 and CH3 regions.
• the protein modeling feature of Alphafold 2.2 developed by Deepmind was implemented to model the 3D structure of each of the wild-type (WT) and mutant constructs of each bovine allotype, IgG2a and IgG2b.
• Molecular Operating Environment developed by Chemical Computing Group (MOE2019.0102) provides a flexible and automated graphical user interface for protein modeling.
• the sequence-to-profile alignment algorithm uses a scoring algorithm to rank the sequence templates and scores higher than 85% ensure the selection of protein templates with physically realistic structures.
• the model was then optimized using the same pipeline and the structural stability of the models was verified using Ramachandran Plots, which checks the stereochemical quality of a protein structure.
• Fig. 3 A The positions for the mutational library are represented in a ball-and-stick form in Fig. 3 A.
• An RMSD plot was generated to calculate the root mean square deviation of the two WT structures, Bovine-IgG2a_WT and Bovine-IgG2b_WT relative to each other (Fig 3B).
• An RMSD value of 2.0A or lower is considered the standard for considering two structures to be alike. Results indicated that Bovine IgG2a construct was identical to the bovine IgG2b allotype with average RMSD value for the structure being 0.57A. RMSDs at the positions where mutational scanning was performed was also noted in Table 2 with values ranging from 0.226 to 0.997A.
• RMSD Root Mean Square Deviation

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