WO2009026638A1 - Marine-animal derived therapeutic and diagnostic agents for hepatitis b - Google Patents

Abstract

The present invention relates generally to cartilaginous marine animal-derived immunoglobulin-like molecules which bind to a Hepatitis B virus (HBV) antigen or precursor or processed form thereof including a monomeric or multimeric form thereof or an antigenic fragment thereof and their use in therapeutic and prophylactic protocols and diagnostic assays for HBV infection.

Description

MARINE-ANIMAL DERIVED THERAPEUTIC AND DIAGNOSTIC AGENTS FOR

HEPATITIS B

FIELD

[0001] The present invention relates generally to cartilaginous marine animal-derived immunoglobulin-like molecules which bind to a Hepatitis B virus (HBV) antigen or precursor or processed form thereof including a monomelic or multimeric form thereof or an antigenic fragment thereof and their use in therapeutic and prophylactic protocols and diagnostic assays for HBV infection.

BACKGROUND

[0002] Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country.

[0003] Bibliographic details of the publications referred to by author in this specification are collected at the end of the description.

[0004] Hepatitis B virus (HBV) infects more than 350 million people globally and is a major health concern causing acute and chronic liver disease, hepatocellular carcinoma and cirrhosis (Kane, Lancet 348:696, 1996). HBV is a small, circular DNA virus with a genome of four overlapping open reading frames (ORFs), which encode the five viral proteins: polymerase (pol); surface antigen (HBsAg), Core antigen (HBcAg), PreCore precursor antigen and x antigen (HBxAg). The PreCore precursor protein is subsequently processed into the secreted PreCore (HBeAg) antigen (Figure IA). The virus can persistently infect the liver and several studies have suggested that the PreCore-Core (PreCore and core) genes, which are transcribed from separate RNA transcripts and translated and processed into both HBeAg and HBcAg, plays an important role in establishing persistent infection (Ou, J Gastroenterol Hepatol i2:S178-187, 1997). [0005] The cellular processing of HBeAg follows a complex pathway. The HBeAg and HBcAg genes are transcribed from separate although highly homologous RNA transcripts. Accordingly, the two proteins share significant amino acid identity (Figure 1). The mature intracellular HBcAg protein (p21^c) of 183 residues (~21kDa) includes an arginine-rich DNA binding protamine domain at the C-terminus. Translation of the preC-C gene for HBeAg produces an immature, unprocessed precursor protein (p25^e). A 29-residue signal peptide at the N-terminus directs the precursor protein to the endoplasmic reticulum for two-step processing. Initially, the 19 N-terminal residues are cleaved (Dienes et al, Hepatology 21:1-1, 1995) to produce an intracellular form of the HBeAg protein (p22^e). The role of the cleaved 19-residue fragment is unknown. Next, the 34 residues encoding the arginine-rich protamine domain are cleaved from the C-terminus by a furin-like protease (Messageot et al, J. Biol Chem 275:891-895, 2003; Takahashi et al, J Immunol 130:2903-2907, 1983) to produce the HBeAg protein (ρl7^e), which is a secreted protein of 159 residues (~18kDa) [Milich et al, Immunol 160:2013-2021 , 1998] .

[0006] The structural assembly of HBeAg and HBcAg is likely to affect their function. Stable HBcAg dimers self assemble in the cellular cytoplasm to form nucleocapsid particles, packaging the viral polymerase and genomic partially dsDNA (Rehermann and Nascimbeni, Nat Rev Immunol 5:215-229, 2005). Structural protein crystallography has been used to determine the structure of recombinant HBcAg to 3.3 A resolution (Wynne et al, MoI Cell 3:771-780, 1999). The structure of HBeAg has not yet been determined. Despite sharing significant amino acid identity with HBcAg, it is unknown if the secreted HBeAg and nucleocapsid HBcAg have structural similarity. It is conjectured that unlike HBcAg, HBeAg does not form dimers or ordered particles (Schodel et al, J Biol Chem 268:1332-1337, 1993) possibly since it is processed at both the N- and C-termini. However, the precursor protein (p25^e) of HBeAg does form capsids and DNA negative Dane particles in vivo (Kimura et al, J Biol Chem 250:21713-21719, 2005), which indicates that multimerization of HBeAg is possible. [0007] The cellular processing of the PreCore protein is complex, the structure undefined, and the function of HBeAg in the viral life cycle is poorly understood (Chen et al, Hepatology 37:27-35, 2003). The HBeAg is a secreted accessory protein, homologous to HBcAg, which is not required for replication, but appears to attenuate host immune response to the intracellular nucleocapsid protein (Chang et al, Jvirol 61 :3322-3325, 1987; Chen et al, proc Natl Acad Sd USA 707:14913-14918, 2004). The HBeAg is, therefore, considered to act as a tolerogen since it contributes to HBV persistence in the infected host (Chen et al, J Virol 79:3016-3021 ', 2005), possibly functioning as an immune toleragen in utero considering that soluble HBeAg traverses the placenta (Milich et al, Proc Natl Acad Sd USA 87:6599-6603, 1990). Furthermore, animal model evidence also indicates that HBeAg regulates the host immune response (Milich 1998 supra).

[0008] Reports have suggested that HBeAg downregulates: (i) cellular genes controlling intracellular signaling (Locarnini et al, J Clin Virol 52:113-121, 2005); and (ii) the ToIl- like receptor 2 (TLR-2) to dampen the innate immune response to viral infection (Riordan et al, Clin Vaccine Immunol 13:912-91¹A, 2006; Visvanathan et al, Hepatology 45:102-110, 2007). hi the absence of HBeAg, HBV replication was associated with upregulation of the TLR2 pathway leading to increased production of TNF-α, a profibrotic cytokine associated with liver fibrosis (Visvanathan et al, 2007 supra). Previous in vitro studies observed increased preC-C gene expression led to HBV replication inhibition (Lamberts et al, J Virol 67:3156-3162, 1993). Conversely, mutations causing reduced preC-C gene expression result in a significant increase in HBV replication (Buckwold et al, J Virol 70:5845-5851, 1996; Carman et al, Lancet 2:588-591, 1989; Scaglioni et al, J virol 77:345-353, 1997). Negative regulation of the HBV replication by the preC-C gene is due to heterodimer of cytosolic HBeAg (p22^e) and HBcAg (p21°), which form unstable core structures (Scaglioni et al, 1997 supra). The intracellular HBeAg (p22^e), a precursor of HBeAg, may elicit effects on the host cell in addition to regulating HBV replication (Locarnini et al, 2005 supra).

[0009] Overall, the reported data on HBeAg suggest that the assessory HBeAg plays a significant role in modulating virus/host interactions to influence the host immune response. Therefore, monitoring of HBeAg may be of clinical relevance. The timely administration of HBV antiviral agents as dictated by HBeAg/HBcAg diagnostic evaluation would improve a patient's response to therapy and reduce the risk of progression to more severe conditions such as hepatocellular carcinoma (HCC), liver cirrhosis and decompensated liver disease. Furthermore, the risk of developing drug resistance mutants would be reduced and/or delayed. There is a need, therefore, to identify agents which specifically target HBeAg and HBcAg.

[0010] The immunoglobulin new antigen receptor (IgNAR) is a unique antibody isotype found only in cartilaginous marine animals (sharks and rays), which has evolved over hundreds of millions of years to be stably expressed in the potent urea environment of the blood stream (Greenberg et al, Nature 374:168-173, 1995; Nuttall et al, MoI Immunol 38:313-326, 2001). The IgNAR response is antigen-driven in the shark, and both immune and naϊve molecular libraries of IgNAR variable domains have been constructed and successfully screened for antigen-specific binding reagents (Greenberg et al, 1995 supra; Nuttall et al, 2001 supra). IgNAR' s are bivalent, but target antigen through a single immunoglobulin variable domain (~14kDa) displaying two complementarity determining region (CDR) loops attached to varying numbers of constant domains (Nuttall et al, Eur J Biochem 270:3543-3554, 2003; Roux et al, Proc Natl Acad Sd USA 95: 11804-11809, 1998). hi contrast, traditional immunoglobulin (Ig) antibodies have a variable heavy (V_H) + variable light (V_L) domain format (~26kDa) and bind antigen through up to six CDRs (Chothia et al, Nature 342:877-883, 1989; Padlan, MoI Immunol 31:169-217, 1994). The small size, and thermodynamic and chemical stability of IgNAR variable domains (V_NA_RS), offer distinct advantages over conventional antibodies. Furthermore, the small V_NAR size enables this unusual antibody domain access to cryptic antigenic epitopes through unusually long and variable CDR3 loops (Greenber et al, 1995 supra; Ewert et al, Biochemistry 41:3628-2636, 2002; Nuttall et al, Proteins 55:187-197, 2004; Stanfield et al, Science 305:1770-1773, 2004; Streltsov et al, Proc Natl Acad Sd USA 101: 12444-12449, 2004; Streltsov et al, Protein Sd 14:2901-2909, 2005). IgNAR domains have been identified that recognize a variety of target antigens including: the apical membrane protein 1 (AMA-I) of P. falciparum (Nuttall et al, 2004 supra); the Kgp protease from Porphyromonas gingivalis (Nuttall et al, FEBS Lett 5i<5:80-86, 2002); cholera toxin (Goldman et al, Anal Chem 75:8245-8255, 2006); the Tom70 mitochondrial membrane spanning protein (Nuttall et al, 2003 supra), and lysozyme (Streltsov et al, 2004 supra).

[0011] Accurate and sensitive binding reagents are the cornerstone of the protein-based therapeutic and diagnostics industry. Given the high rates of acute and chronic HBV infection worldwide, there is an urgent need for such reagents targeting HBV proteins for use in therapeutic and diagnostic protocols.

SUMMARY

[0012] Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or integer or group of elements or integers but not the exclusion of any other element or integer or group of elements or integers.

[0013] Nucleotide and amino acid sequences are referred to by a sequence identifier number (SEQ DD NO). The SEQ ID NOs correspond numerically to the sequence identifiers <400>l (SEQ ID NO:1), <400>2 (SEQ ID NO:2), etc. A summary of the sequence identifiers is provided in Table 1. A sequence listing is provided after the claims. Abbreviations used herein are defined in Table 2.

[0014] The present invention provides cartilaginous marine animal-derived immunoglobulin-like molecules which bind to HBeAg and/or HBcAg or precursor or proposed forms thereof. More particularly, the immunoglobulin-like molecules comprise the variable domain of an IgNAR (Immunoglobulin new antigen receptor), referred to as

"V_NAR"- The immunoglobulin-like molecules of the present invention enable the selective targeting of HBeAg and HBcAg and their precursor or processed forms which include monomeric or multimeric forms thereof which is useful in the context of disease progression, enabling rapid selection of appropriate treatment regimens. The selective targeting may be extracellular or intracellular, hi relation to the latter, the IgNAR may be engineered to be produced in a cell or engineered to be directed intracellularly to target a particular molecule (e.g. PreCore protein). In addition, selection of therapeutic protocols based on early or more sensitive detection of HBeAg and/or HBcAg improves therapeutic outcomes and enables the selection of appropriate therapeutic protocols. This is particularly the case given the inhibiting effects of HBeAg on the innate immune system.

[0015] The present invention provides, therefore, therapeutic and diagnostic agents which target HBeAg and/or HBcAg or precursor or processed forms thereof. A "processed form" includes monomeric and multimeric forms of HBeAg or HBcAg. [0016] Accordingly, one aspect of the present invention provides an isolated, cartilaginous marine animal-derived immunoglobulin-like molecule which binds to HBeAg and/or HBcAg or a precursor or processed form thereof. The binding may occur in extracellular or intracellular environments or within a membranous environment. When targeting intracellular molecules, the IgNARs maybe referred to herein as an "intrabody".

[0017] In a particular embodiment, the immunoglobulin-like molecule comprises a variable domain of an IgNAR, referred to herein as VN_AR- IgNARs are described in International Patent Application No. WO 2005/118629.

[0018] The present invention provides an isolated V_NAR domain of an IgNAR comprising an amino acid sequence selected from the list consisting of SEQ ID NO:1 and SEQ ID NO:2 or an amino acid sequence having at least 80% similarity thereto wherein said V_NAR domain binds to HBeAg and/or HBcAg or a precursor or processed form thereof.

[0019] Another particular embodiment of the present invention provides an isolated V_NAR domain of an IgNAR comprising an amino acid sequence selected from the list consisting of SEQ ID NO:1 and SEQ ID NO:2 or an amino acid sequence having at least 80% similarity thereto wherein said V_NAR domain binds to HBeAg and/or HBcAg or a precursor or processed form thereof.

[0020] It is proposed herein to use the IgNARs or VN_ARS as therapeutic agents in the treatment of acute or chronic Hepatitis B infection. The agents may be used alone or in combination with other anti-viral agents. The IgNARs may be produced in a cell or moidifed to be directed intracellularly to target a particular molecule. The IgNARs or V_NA_RS of the present invention may also be used in diagnostic protocols to detect HBV infection or to monitor a treatment protocol in order to modify the treatment if necessary. A modified treatment protocol includes changing from one anti-viral agent to another.

[0021] Hence, methods of treatment and prophylaxis, methods of monitoring a therapeutic protocol and diagnostic assays are all encompassed by the present invention.

[0022] The present invention is further directed to the use of cartilaginous marine animal- derived immunoglobulin-like molecule which binds to human hepatitis B e antigen (HBeAg) [PreCore] and/or human hepatitis core antigen (HBcAg) or a precursor or processed form thereof or a fragment thereof in the manufacture of a medicament for the treatment or prophylaxis of HBV infection.

[0023] Another aspect contemplates the use of cartilaginous marine animal-derived immunoglobulin-like molecule which binds to human hepatitis B e antigen (HBeAg) and/or human hepatitis core antigen (HBcAg) or a precursor or processed form thereof or a fragment thereof in the manufacture of a medicament to enhance innate immunity.

TABLE l

Summary of sequence identifiers

TABLE 2

Abbreviations

BRIEF DESCRIPTION OF THE FIGURES

[0024] A figure may contain color representations or entities. Color photographs are available from the Patentee upon request or from an appropriate Patent Office. A fee may be imposed if obtained from a Patent Office.

[0025] Figures IA and B are diagrammatic and informational representations showing processing and comparative alignment of HBeAg and HBcAg. (A) The PreCore precursor protein is processed N- and C-terminally to produce the HBeAg of 159 residues (~18kDa), numbered -10 to 149. The 10 N-terminal signal sequence residues are unique to HBeAg. The HBcAg produced from a separate RNA transcript consists of 183 residues (-2IkDa) numbered 1-183, and has 34 unique residues C-terminally. The HBeAg and HBcAg share a common core domain of 149 residues. (B) Sequence alignment of HBeAg and HBcAg, highlighting the 10 N-terminal HBeAg unique residues (underlined), and the 34 C-terminal HBcAg unique residues (italicized) .

[0026] Figures 2A through D are an informational and graphical representations showing identification of HBeAg/HBcAg specific VN_ARS. (A) Comparative alignment of the amino acid sequences of the two identified V_NA_RS, H6 and H3. The four dissimilar residues are indicted in bold and underlined. The CDR 1 and CDR 3 regions are boxed and shaded for identification. (B) Elution profile of affinity-purified H6 V_NAR protein on a Superdex 75 HR10/30 column equilibrated in PBS, pH 7.4 and run at a flow rate of 0.5 ml/min. The peak eluting at 29 min is consistent with a monomelic domain (calculated M₁- 14.7kDa). The absorbance at A₂₈o_nm is given in arbitrary units. Standard M_r in kDa are indicated. The inset in shows the V_NA_R H6 sample analyzed by SDS-PAGE (10% w/v). (C) As for (B) except VN_AR H3. (D) Comparative ELISA analysis of the binding specificity of V_NA_R H6 with non-specific control V_NAR domain for the immobilized HBeAg and HBcAg purified target antigens, and for GST and Lysozyme (negative control proteins). Data represent the average of triplicate wells and are normalized to PBS background. [0027] Figures 3A through D are graphical representations showing binding affinity of VNARS H6 and H3 for HBeAg and HBcAg target antigens. Overlaid BIAcore sensorgrams showing the interaction between HBeAg or HBcAg and peak-purified monomelic VN_AR protein H6 or H3 (ranging 26.25 to 420nm) as analyte. The HBeAg-GST or HBcAg-GST fusion protein was first captured by binding to an immobilized mouse anti-GST antibody; binding was measured in HBS buffer at a constant flow rate of 30μl/min with an injection volume of 90 μL. Data were averaged from triplicate experiments (A) Binding affinity interactions of captured HBeAg-GST Ag with V_NAR H6 analyte; (B) Binding affinity interactions of captured HBcAg-GST Ag with V_NAR H6 analyte; (C) As for (A) except VNAR H3 (D) AS for (B) except V_NAR H3.

[0028] Figure 4 is a graphical representation of an analysis of VNAR H6 affinity by ELISA for mammalian produced HBeAg/HBcAg. Purified H6 V_NA_R coated to ELISA plate wells was tested for binding affinity to HBeAg and HBcAg produced in transiently (pCI) or stably (pTRE) transfected Huh-7 cells, localized to the cell lysate or exported into culture supernatant. Empty vector was incorporated as a control. Data represent the average of quadruplicate wells from duplicate experiments.

[0029] Figure 5 is a graphical representation of an analysis of H6 V_NAR affinity for HBeAg by competitive ELISA. Purified HBeAg coated to ELISA plate wells was detected by H6 V_NA_R alone, in comparison to H6 VNA_R in competition with several other antibodies with specificity for HBeAg.

[0030] Figure 6 is a graphical representation showing epitope mapping of H6 V_NAR using an overlapping peptide library. H6 VNA_R recognition was interrogated on a linear epitope library of biotinylated peptides to HBeAg immobilized on streptavidin coated ELISA plate wells. A non-specific V_NAR library clone was incorporated as a control.

[0031] Figure 7 is a photographic representation of dectection of H6 intrabody transfected into stable PreCore or core cell lines. PreCore: pc47; Core: C4B

Intrabody: (MB)

[0032] Figure 8 represent photographic and graphical depections of analysis of PreCore and core protein expression in stable cell lines transfected with H6 intrabody construct.

PreCore: pc47

Core: C4B Control: pTRE

Lysate: Lys

Sn: Supernatant

[0033] Figure 9 is a graphical representation of quantitative PreCore and core proetien expression analysis.

PreCore: pc47

Core: C4B

Control: pppTRE Intrabody: MB

DETAILED DECRIPTION

[0034] The present invention provides cartilaginous marine animal-derived immunoglobulin-like molecules which bind HBeAg and/or HBcAg or a precursor or processed form thereof.

[0035] The cartilaginous marine animal-derived immunoglobulin molecule is referred to as "IgNAR" for immunoglobulin new antigen receptor (Nuttal et al, 2003 supra; WO 2005/118629). The variable domain is referred to as a V_NAR- IgNARs are classified in relation to their time of appearance during marine animal development and disulfide bonding patterns within variable domains. The categories are Type I V_NAR> Type 2 VN_AR and Type 3 VN_AR (Nuttal et al, 2003 supra). Hence, the present invention encompasses an isolated Type 1 or 2 or 3 V_NA_R from an IgNAR which binds to HBeAg and/or HBcAg or a precursor or processed form thereof.

[0036] Reference to a "precursor form" or "processed form" of HBeAg or HBcAg includes extracellular and intracellular forms. Hence, the IgNAR contemplated herein may bind to extracellular HBeAg (e.g. pl7^e) or intracellular HBeAg (e.g. p22^e or p25^e) and/or extracellular HBcAg or intracellular HBcAg (e.g. p21^c). A "processed form" also includes an HBeAg or HBcAg which has undergone some form of proteolytic cleavage, whether by an HBV-encoded enzyme by a host cell enzyme or by laboratory intervention. Other "processed forms" include monomeric or multimeric forms of HBeAg or HBcAg. A "multimer" includes dimmers, trimers, etc. This is particularly the case for intracellular forms of HBcAg.

[0037] Reference to a "cartilaginous marine animal" includes a member of the families of shark and ray. Reference to a "shark" includes a member of order Squatiniform.es, Pristiophoriformes, Squaliformes, Carcharinformes, Laminiformes, Orectolobiformes, Heterodontiformes and Hexanchieformes. Whilst not intending to limit the shark to any one genus, immunoglobulins from genus Orectolobus are particularly useful and include the bamboo shark, zebra shark, blind shark, whale shark, nurse shark and Wobbegong. Immunoglobulins from Orectolobus maculates (Wobbegong) are exemplified herein.

[0038] The "immunoglobulins" from cartilaginous marine animals may be referred to herein as "immunoglobulin-like" to emphasize that the cartilaginous marine animal- derived molecules are structurally different to mammalian or avian-derived immunoglobulins. See Nuttal et al, 2003 supra. For brevity, all cartilaginous marine animal-derived immunoglobulin-like molecules are referred to herein as "IgNARs". The variable domain from an IgNAR is referred to as a VNA_R- The term "intrabody" is used to describe an IgNAR produced by a cell or which is targeted to within a cell.

[0039] Reference to "derived" includes vaccination of a fish and collection of blood or immune sera or other body fluid as well as the generation of molecules via recombinant means. By "recombinant means" includes generation of cartilaginous marine animal- derived nucleic acid libraries and biopanning expression libraries (such as phagemid libraries) for IgNAR proteins which interact with HBeAg and/or HBcAg or precursor or processed forms thereof.

[0040] Hence, one aspect of the present invention is directed to an isolated, cartilaginous marine animal-derived immunoglobulin-like molecule which binds to HBeAg and/or HBcAg or precursor or processed form thereof.

[0041] More particularly, an IgNAR or variable domain region thereof (VNA_R) is provided which binds to HBeAg and/or HBcAg or a precursor or processed form thereof.

[0042] Still even more particularly, a further aspect contemplates an isolated VNA_R which binds to HBeAg and/or HBcAg or a precursor or processed form thereof.

[0043] The IgNAR or VNA_R of the present invention may bind to an extracellular or intracellular form of HBeAg or HBcAg or a precursor or processed form thereof. Hence, the IgNAR may be generated within a cell or is in a form which is directed to an intracellular target. [0044] Furthermore, IgNAR molecules including VNAR molecules are contemplated herein which specifically bind to HBeAg (pl7^e) or p22^e or other intracellular forms of HBeAg (e.g. p25^e) and/or to HBcAg or its intracellular forms (e.g. p21^c) to the exclusion of all other binding which is specific. Non-specific binding may still occur but this would still be regarded as specific binding to HBeAg or HBcAg.

[0045] Another aspect of the present invention is directed to an isolated IgNAR or V_NA_R region thereof which binds to an HBV antigen selected from the list consisting of:

(i) an extracellular or intracellular form of HBeAg or a precursor or processed form thereof;

(ii) an extracellular or intracellular form of HBcAg or a precursor or processed form thereof; and

(iii) an extracellular or intracellular form of both HBeAg and HBcAg or a precursor or processed form thereof.

[0046] Another embodiment contemplates a crystal of a V_NAR domain of a Type 1 or 2 or 3 IgNAR. Generation of a crystal or elucidation of a crystal structure enables the atomic coordinates to be resolved. These data can then be used for in silico design and selection of mimetics.

[0047] Two particularly useful VN_AR peptides comprise amino acid sequences set forth in SEQ ID NO:1 (referred to herein as "H6") and SEQ ID NO:2 (referred to herein as "H3"). These V_NARS interact with conformational epitope(s) on HBeAg and/or HBcAg or on their precursor or processed (including monomelic or multimeric) forms. It is proposed herein that a conformational epitope lies within or is associated with the extended CDR2 loop.

[0048] Hence, the present invention provides an isolated V_NA_R domain of an IgNAR comprising an amino acid sequence selected from the list consisting of SEQ ID NO:1 and SEQ ID NO:2 or an amino acid sequence having at least 80% similarity thereto wherein said VNA_R domain binds to HBeAg and/or HBcAg or a precursor or processed form thereof.

[0049] Reference to "80% similarity" includes "80% identity" and covers at least 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 and 99% or greater.

[0050] The term "similarity" as used herein includes exact identity between compared sequences at the amino acid level. Where there is non-identity, "similarity" includes amino acids that are nevertheless related to each other at the structural, functional, biochemical and/or conformational levels.

[0051] Encompassed within the scope of the present invention are modifications to the VNA_RS such as modifications to SEQ ID NO:1 or 2 which are tantamount to conservative substitutions but which potentially alter a property of the IgNAR variable domain such properties include stability, serum half life and cell penetrability. Examples of conservative substitutions are given in as follows:

TABLE 3

Amino Acid Abbreviations

Amino Acid Three-letter Abbreviation One-letter Symbol

Alanine Ala A

Arginine Arg R

Asparagine Asn N

Aspartic acid Asp D

Cysteine Cys C

Glutamine GIn Q

Glutamic acid GIu E

Glycine GIy G

Histidine His H

Isoleucine He I

Leucine Leu L

Lysine Lys K

Methionine Met M

Phenylalamine Phe F

Proline Pro P

Serine Ser S

Threonine Thr T

Tryptophan Trp W

Tyrosine Tyr Y

Valine VaI V [0052] Furthermore, if desired, unnatural amino acids or chemical amino acid analogs can be introduced as a substitution or addition into the polypeptides of the present invention. Such amino acids include, but are not limited to, the D-isomers of the common amino acids, 2,4-diaminobutyric acid, α-amino isobutyric acid, 4- aminobutyric acid, 2- aminobutyric acid, 6-amino hexanoic acid, 2-amino isobutyric acid, 3 -amino propionic acid, ornithine, norleucine, norvaline, hydroxyproline, sarcosine, citrulline, homocitrulline, cysteic acid, t-butylglycine, t-butylalanine, phenylglycine, cyclohexylalanine, /3-alanine, fluoro-amino acids, designer amino acids such as jS-methyl amino acids, Cα-methyl amino acids, Nα-methyl amino acids, and amino acid analogues in general.

[0053] The terms "peptide", "polypeptide" or "protein" may be used herein to describe the isolated IgNAR or V_NAR molecules. The term "intrabody" may also be used.

[0054] Also included within the scope of the present invention are chemically modified derivates of IgNAR variable domains which may provide advantages such as increasing stability and circulating time of the polypeptide, or decreasing immunogenicity (see, for example, U.S. Patent No. 4,179,337). The chemical moieties for derivatization may be selected from water-soluble polymers such as polyethylene glycol, ethylene glycol/propylene glycol copolymers, carboxyniethylcellulose, dextran, polyvinyl alcohol and the like.

[0055] Also included within the scope of the subject invention are VNA_RS that are differentially modified during or after synthesis, for example, by biotinylation, benzylation, glycosylation, acetylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to an antibody molecule or other cellular ligand, etc. The VNA_R may be modified at random positions within the molecule or at predetermined positions within the molecule and may include one, two, three or more attached chemical moieties. These modifications may, for example, serve to increase the stability and/or bioactivity of the modified domains. [0056] The IgNAR variable domains may also be modified by having C- or N-terminal truncations. However, the scope for such modifications is limited and generally no more than eight, or no more than six or no more than four residues be removed. Preferably there is no truncation at the N-terminal and no truncation at either the N- or C-terminal end. The present invention further contemplates modified IgNAR molecules which comprise removal of the C-terminal double flag tag. In one embodiment this comprises removal of eight or more amino acids.

[0057] Modified VNA_R domains of the present invention can be produced in a variety of ways, including production and recovery of natural proteins, production and recovery of recombinant proteins, and chemical synthesis of the proteins. In one embodiment, an isolated polypeptide of the present invention is produced by culturing a cell capable of expressing the polypeptide under conditions effective to produce the polypeptide and recovering the polypeptide.

[0058] Modifications can also be made to regions of the IgNAR variable domain that are not solvent exposed and/or which do not form part of a binding loop, e.g. the β strand regions. In another embodiment, the modification increases or decreases the propensity for the IgNAR variable domain to form homodimers compared to an unmodified IgNAR variable domain.

[0059] In yet another embodiment, the modification increases the solubility of the IgNAR variable domain compared to the unmodified IgNAR variable domain.

[0060] In still another embodiment, one or more solvent exposed loops is/are modified to improve solubility. Solubility may be improved by, for example, either removing disulphide bond-forming cysteines and/or replacing disulphide bond-forming cysteines from within the solvent exposed loops with amino acids such as alanine or serine.

[0061] Modifications to improve solubility may be desirable where the V_NA_RS are being designed to function in an intracellular context and/or their method of production favors expression in a soluble form. It will also be evident to the skilled artisan that it may be necessary to modify the solubility characteristics of the V_NA_RS at the same time or even prior to making other modifications, such as, changing the binding characteristics.

[0062] The physicochemical properties, such as stability and solubility, of the IgNAR variable domains may be qualitatively and/or quantitatively determined using a wide range of methods known in the art. Methods which may find use in the present invention for characterizing the biophysical/physicochemical properties of the binding moieties include gel electrophoresis, chromatography such as size exclusion chromatography, reversed- phase high performance liquid chromatography, mass spectrometry, ultraviolet absorbance spectroscopy, fluorescence spectroscopy, circular dichroism spectroscopy, isothermal titration calorimetry, differential scanning calorimetry, analytical ultra-centrifugation, dynamic light scattering, proteolysis, cross-linking, turbidity measurement, filter retardation assays, immunological assays, fluorescent dye binding assays, protein-staining assays, microscopy, and detection of aggregates via ELISA or other binding assay. Structural analysis employing X-ray crystallographic techniques and NMR spectroscopy may also find use.

[0063] Protein stability (e.g. structural integrity) may, for example, be determined by measuring the thermodynamic equilibrium between folded and unfolded states.

[0064] In one embodiment, stability and/or solubility may be measured by determining the amount of soluble protein after some defined period of time. In such an assay, the protein may or may not be exposed to some extreme condition, for example elevated temperature, low pH, or the presence of denaturant. Because unfolded and aggregated protein is not expected to maintain its function, e.g. be capable of binding to a predetermined target molecule, the amount of activity remaining provides a measure of the binding moieties stability and solubility. Thus, one method of assessing solubility and/or stability is to assay a solution comprising a binding moiety for its ability to bind a target molecule, then expose the solution to elevated temperature for one or more defined periods of time, then assay for antigen binding again. [0065] Alternatively, the modified IgNAR binding domains could be expressed in prokaryotic expression systems and the protein isolated from the cell lysate by a series of biochemical purification steps including differential centrifugation, affinity isolation chromatography using attached tags such as poly histidine, ion-exchange chromatography and gel filtration chromatography. A measure of the improvement in the solubility of the modified polypeptide can be obtained by making a comparison of the amount of soluble protein obtained at the end of the purification procedure to that obtained using the unmodified polypeptide, when starting with a similar amount of expressed unfractionated product. Levels of expression of product in culture can be normalized by a comparison of product band densities after polyacrylamide gel electrophoresis of equivalent aliquots of SDS detergent-solubilized cell lysate.

[0066] In addition, IgNAR variable domains can be unfolded using chemical denaturant, heat, or pH, and this transition be monitored using methods including, but not limited to, circular dichroism spectroscopy, fluorescence spectroscopy, absorbance spectroscopy, NMR spectroscopy, calorimetry, and proteolysis. As will be appreciated by those skilled in the art, the kinetic parameters of the folding and unfolding transitions may also be monitored using these and other techniques.

[0067] The solubility of the IgNAR variable domains of the present invention preferably correlates with the production of correctly folded, monomelic polypeptide. The solubility of the modified IgNAR variable domains may therefore also be assessed by HPLC or FPLC. For example, soluble (non-aggregated) domains will give rise to a single peak on a HPLC or FPLC chromatograph, whereas insoluble (aggregated) domains will give rise to a plurality of peaks. Furthermore, the ability to be able to correctly fold and form ordered crystal leads and structures is also often indicative of good solubility.

[0068] As an example of an accelerated stability trial, aliquots of the IgNAR variable domain can be stored at different temperatures, such as -20⁰C, 4°C, 20°C and 37⁰C and an activity of the VNAR assayed at different time intervals. For example, successful maintenance of activity during storage at 37⁰C for 12 weeks is roughly equivalent to storage stability for 12 months at 4⁰C. The trial can also be conducted to compare the effect of different protecting additives in the storage buffer on the stability of the protein. Such additives can include compounds such as glycerol, sorbitol, non-specific protein such as bovine serum albumin, or other protectants that might be used to increase the shelf life of the protein.

[0069] The IgNARs or VN_ARS of the instant invention can be linked to other molecules, typically by covalent or non-covalent means. For example, binding moieties may be produced as fusion proteins, linked to other polypeptide sequences. Fusion partners can include enzymes, detectable labels, therapeutic moieties, cytotoxic moieties and/or affinity tags for numerous therapeutic or diagnostic applications or to aid in purification. Fusion partners, without restriction, may be GFP (green fluorescent protein), GST (glutathione S- transferase), thioredoxin or hexahistidine. Other fusion partners include targeting sequences that direct binding moieties to particular sub-cellular locations or direct binding moieties to extracellular locations e.g. secretion signals. Heterologous fusion sequences contemplated herein include for example, immunoglobulin fusions, such as Fc fusions, or fusions to other cellular ligands which may increase stability or aid in purification of the protein.

[0070] Therapeutic or diagnostic agents that can be linked to the IgNAR or VN_AR molecules herein include pharmacologically active substances such as toxins or prodrugs, immunomodulatory agents, nucleic acids, such as inhibitory nucleic acids or nucleic acids encoding polypeptides, molecules that enhance the in vivo stability or lipophilic behavior of the binding moieties such as PEG, and detectable labels such as radioactive compounds, dyes, chromophores, fluorophores or other imaging reagents.

[0071] Binding moieties may also be immobilized to a solid phase, such as a substantially planar surface (e.g. a chip or a microtitre plate) or beads. Techniques for immobilizing polypeptides to a solid phase are known in the art. In addition, where libraries of binding moieties are used (e.g. in screening methods), arrays of binding moieties immobilized to a solid phase can be produced (Lee and Mrksich, Trends Biotechnol. 20(12 Suppl):S14-S, 2002 and references contained therein). Such immobilized solid phases are particularly useful in diagnostic applications.

[0072] In another embodiment of the subject invention, the IgNARs or VNA_RS herein function as a protein scaffold with other polypeptide sequences being inserted into solvent- exposed regions of the binding moiety for display on the surface of the scaffold. Such scaffolds may, for example, serve as a convenient means to present peptides in a conformationally constrained manner. These scaffolds may be used to produce V_NARS with altered binding specificities and also to produce and/or screen for binding moieties or mimetics having specificity for any target molecule of interest (e.g. various forms of HBeAg or HBcAg).

[0073] The present invention also provides a polynucleotide encoding a IgNAR or VNA_R which is capable of binding to an HBeAg or HBcAg or a precursor or processed form thereof. The present invention also provides a vector comprising the polynucleotide. The present invention further provides a host cell comprising the vector.

[0074] The present invention also provides a method of producing an IgNAR or VNA_R which comprises culturing a host cell of the present invention under conditions enabling expression of the IgNAR or V_NAR and optionally recovering the immunoglobulin.

[0075] Polynucleotides of the invention may comprise DNA or RNA. They may be single- stranded or double-stranded. They may also be polynucleotides which include within them synthetic or modified nucleotides. A number of different types of modifications to oligonucleotides are known in the art. These include methylphosphonate and phosphorothioate backbones, addition of acridine or polylysine chains at the 3' and/or 5' ends of the molecule. For the purposes of the present invention, it is to be understood that the polynucleotides described herein may be modified by any method available in the art. Such modifications may be carried out in order to enhance the in vivo activity or life span of polynucleotides of the invention. [0076] Polynucleotides of the present invention can be incorporated into a recombinant replicable vector. The vector may be used to replicate the nucleic acid in a compatible host cell.

[0077] Conveniently, a polynucleotide in a vector is operably linked to a control sequence that is capable of providing for the expression of the coding sequence by a host cell or using an in vitro transcription/translation system, i.e. the vector is an expression vector. The term "operably linked" means that the components described are in a relationship permitting them to function in their intended manner. A regulatory sequence "operably linked" to a coding sequence is ligated in such a way that expression of the coding sequence is achieved under condition compatible with the control sequences.

[0078] The control sequences may be modified, for example by the addition of further transcriptional regulatory elements to make the level of transcription directed by the control sequences more responsive to transcriptional modulators.

[0079] Vectors may be transformed or transfected into a suitable host cell to provide for expression of a binding moiety according to the invention. This process may comprise culturing a host cell transformed with an expression vector under conditions to provide for expression by the vector of a coding sequence encoding the IgNAR or VNAR and optionally recovering same.

[0080] The vectors may be, for example, plasmid, phagemid or virus vectors provided with an origin of replication, optionally a promoter for the expression of the said polynucleotide and optionally a regulator of the promoter. The vectors may contain one or more selectable marker genes, for example an ampicillin resistance gene in the case of a bacterial plasmid or a neomycin resistance gene for a mammalian vector. Vectors may be used, for example, to transfect or transform a host cell. [0081] Control sequences operably linked to sequences encoding the protein of the invention include promoters/enhancers and other expression regulation signals. These control sequences may be selected to be compatible with the host cell for which the expression vector is designed to be used in. The term "promoter" is well-known in the art and encompasses nucleic acid regions ranging in size and complexity from minimal promoters to promoters including upstream elements and enhancers.

[0082] The promoter is typically selected from promoters which are functional in prokaryotic or eukaryotic cells. With respect to eukaryotic promoters, they may be promoters that function in a ubiquitous manner or, alternatively, a tissue-specific manner. They may also be promoters that respond to specific stimuli. Viral promoters may also be used, for example the Moloney murine leukaemia virus long terminal repeat (MMLV LTR) promoter, the rous sarcoma virus (RSV) LTR promoter or the human cytomegalovirus (CMV) IE promoter.

[0083] It may also be advantageous for the promoters to be inducible so that the levels of expression of the binding moiety can be regulated during the life-time of the cell. Inducible means that the levels of expression obtained using the promoter can be regulated.

[0084] In an embodiment of the present invention, a heterologous sequence is inserted into the VN_AR domain. Such modifications may be made by manipulating polynucleotides encoding the VN_AR- This may conveniently be achieved by providing cloning vectors that comprise a sequence encoding a domain which sequence comprises one or more unique insertion sites to allow for easy insertion of nucleotide sequences encoding heterologous sequences into the appropriate region of the domain. A heterologous sequence, as indicated above, includes therapeutic or cytotoxic agents, diagnostic agents and protein purification agents.

[0085] Vectors and polynucleotides of the invention may be introduced into host cells for the purpose of replicating the vectors/polynucleotides and/or expressing the IgNAR or

VNA_R molecules for production purposes Any suitable host cell may be used, including prokaryotic cells (such as Escherichia coli, Streptomyces spp. and Bacillus subtilis) and eukaryotic cells. Suitable eukaryotic cells include insect cells (e.g. using the baculovirus expression system), mammalian cells, fungal (e.g. yeast) cells and plant cells, useful mammalian cells are animal cells such as CHO, COS, C 127, 3T3, HeLa, HEK 293, NIH 3T3, BHK and Bowes melanoma such as CHO-K15 C0S7, Yl adrenal and carcinoma cells.

[0086] Vectors/polynucleotides may introduced into suitable host cells using any of a large number of techniques known in the art such as, for example, transfection (for example calcium phosphate transfection or DEAE-Dextran mediated transfection), transformation and electroporation. Where vectors/polynucleotides of the invention are to be administered to animals, several techniques are known in the art, for example infection with recombinant viral vectors such as retroviruses, herpes simplex viruses and adenoviruses, direct injection of nucleic acids and biolistic transformation.

[0087] The recombinant IgNAR or V_NA_R polypeptides of the present invention can be extracted from host cells by a variety of techniques known in the art, including enzymatic, chemical and/or osmotic lysis and physical disruption.

[0088] Cell-free translation systems can also be used to produce the molecules. Appropriate cloning and expression vectors for use with prokaryotic and eukaryotic hosts are described in Sambrook et at, Molecular Cloning: A Laboratory Manual, Second Edition, Cold Spring Harbor, N. Y., 1989.

[0089] The IgNARs or VNA_RS of the present invention may also be provided as libraries comprising a plurality of molecules which have different sequences in the IgNAR variable domain. Variations may also reside in one or more CDR loops. These libraries can typically be used in screening methods to identify molecules which bind to a particular form of HBeAg or HBcAg.

[0090] Libraries are conveniently provided as libraries of polynucleotides encoding the IgNAR or VNA_R molecules. The polynucleotides are generally mutagenized or randomized to produce a large number of different sequences which differ at one or more positions within at least one β strand or loop region.

[0091] The IgNAR or VNA_R of the present invention may be in monomeric or multimeric form which includes dimmers, trimers, quadramers, etc. Multimers may associate by a variety of means such as via disulfide bonds, covalent bonds, electrostatic interactions and so on.

[0092] The IgNAR and V_NAR molecules herein are proposed to be useful therapeutic or prophylactic agents to target HBcAg or HBcAg (or their precursor or processed forms) which facilitates HBV clearance, improving innate immunity, potentially reduced in the presence of HBeAg or HBcAg and in preventing re-infection in acute or chronic HBV infection.

[0093] Hence, another aspect of the present invention contemplates a method for the treatment or prophylaxis of HBV infection said method comprising administering to a subject an effective amount of an IgNAR or VNAR which binds to or is specific for HBeAg or HBcAg or a precursor or processed form thereof.

[0094] The present invention is further directed to the use of cartilaginous marine animal- derived immunoglobulin-like molecule which binds to human hepatitis B e antigen (HBeAg) and/or human hepatitis core antigen (HBcAg) or a precursor or processed form thereof or a fragment thereof in the manufacture of a medicament for the treatment or prophylaxis of HBV infection.

[0095] Reduction in HBeAg and/or HBcAg is also proposed to improve or enhance suppressed innate immunity such as via TLR2 or TLR4.

[0096] Accordingly, another aspect contemplates the use of cartilaginous marine animal- derived immunoglobulin-like molecule which binds to human hepatitis B e antigen

(HBeAg) and/or human hepatitis core antigen (HBcAg) or a precursor or processed form thereof or a fragment thereof in the manufacture of a medicament to enhance innate immunity.

[0097] Hence, the IgNAR or VNA_R molecules of the present invention may be used as therapeutic agents to bind to and inactivate or otherwise modify extracellular or intracellular forms of HBeAg or HBcAg. The IgNAR or V_NAR molecules may be used without modification or subjected to deimmunization or, in the case of human use, humanization. The present invention provides therefore the application of biochemical techniques to render an IgNAR or V_NAR substantially non-immunogenic in a subject to be treated (generally a human). Reference herein to "deimmunization" or "humanization" includes processes such as complementary determinant region (CDR) grafting, "reshaping" with respect to a framework region of an immunoglobulin molecule and variable (v) region mutation, all aimed at reducing the immunogenicity of an IgNAR or V_NAR-

[0098] The aim is to reduce immunogenicity of the IgNAR or V_NA_R compared to an immunoglobulin before exposure to deimmunization processes. The term "immunogenicity" includes an ability to provoke, induce or otherwise facilitate a humoral and/or T-cell mediated response in a host animal. Particularly convenient immunogenic criteria include the ability for amino acid sequences derived from a variable (v) region of an IgNAR to interact with MHC class π molecules thereby stimulating or facilitating a T- cell mediating response including a T-cell-assisted humoral response.

[0099] Deimmunization or humanization of IgNARs or VN_ARS may take any of a number of forms including the preparation of chimeric immunoglobulins which have the same or similar specificity as the primary IgNARs or VN_ARS. Chimeric immunoglobulins whose light and heavy chain genes have been constructed, typically by genetic engineering, from immunoglobulin variable and constant region genes belonging to different species generally a human. Thus, in accordance with the present invention, techniques are used to produce interspecific antibodies wherein the binding region of an IgNAR is combined with a non-binding region of a human antibody (Liu et al, Proc. Natl. Acad. Sd. USA 84:3439- 3443, 1987). For example, the CDRs from an IgNAR can be grafted onto a human antibody, thereby "humanizing" the VN_AR (European Patent Publication No. 0 239 400, Jones et al, Nature 321:522-525, 1986, Verhoeyen et al, Science 239:1534-1536, 1988 and Richmann et al, Nature 332:323-327, 1988). In this case, the deimmunizing process is specific for humans. More particularly, the CDRs can be grafted onto a human antibody variable region with or without human constant regions. The IgNAR or V_NA_R providing the CDRs is typically referred to as the "donor" and the human antibody providing the framework is typically referred to as the "acceptor". Constant regions need not be present. Hence, all parts of a humanized immunization, except possibly the CDRs, are substantially identical to corresponding parts of natural human immunoglobulin sequences.

[0100] It will be understood that the deimmunized IgNARs or V_NARS may have additional conservative amino acid substitutions which have substantially no effect on antigen binding or other immunoglobulin functions.

[0101] Exemplary methods which may be employed to produce deimmunized antibodies according to the present invention are described, for example, in (Richmann et al, 1988 supra, Chou et al, (U.S. Patent No. 6,056,957), Queen et al, (U.S. Patent No. 6,180,377), Morgan et al, (U.S. Patent No. 6,180,377) and Chothia et al, J. MoI. Biol. 196:901, 1987).

[0102] The deimmunized or humanized IgNARs or VNA_RS are generally administered with a pharmaceutical carrier, which is non toxic to cells and the individual.

[0103] The carrier may take a wide variety of forms depending on the form of preparation desired for administration, e.g., oral or parenteral (including intravenous). In preparing compositions for oral dosage form, any of the usual pharmaceutical media may be employed, such as, for example, water, glycols, oils, alcohols, flavoring agents, preservatives, colouring agents and the like in the case of oral liquid preparations, such as, for example, suspensions, elixirs and solutions; or carriers such as starches, sugars, microcrystalline cellulose, diluents, granulating agents, lubricants, binders, disintegrating agents and the like in the case of oral solid preparations such as, for example, powders, capsules and tablets, with the solid oral preparations being preferred over the liquid preparations. Because of their ease of administration, tablets and capsules represent the most advantageous oral dosage unit form in which case solid pharmaceutical carriers are obviously employed. If desired, tablets may be coated by standard aqueous or nonaqueous techniques.

[0104] Such compositions may be prepared by any of the methods of pharmacy but all methods include the step of bringing into association the active ingredient with the carrier which constitutes one or more necessary ingredients. In general, the compositions are prepared by uniformly and intimately admixing the active ingredient with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product into the desired presentation. For example, a tablet may be prepared by compression or molding, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing in a suitable machine, the active ingredient in a free-flowing form such as powder or granules, optionally mixed with a binder, lubricant, inert diluent, surface active or dispersing agent. Molded tablets may be made by molding in a suitable machine, a mixture of the powdered compound moistened with an inert liquid diluent.

[0105] The IgNARs or V_NA_RS of the present invention may be administered orally, parenterally (including subcutaneous injections, intravenous, intramuscular, intrasternal injection or infusion techniques), by inhalation spray, or rectally, in dosage unit formulations containing conventional non-toxic pharmaceutically acceptable carriers, adjuvants and vehicles.

[0106] When administered by nasal aerosol or inhalation, these compositions are prepared according to techniques well-known in the art of pharmaceutical formulation and may be prepared as solutions in saline, employing benzyl alcohol or other suitable preservatives, absorption promoters to enhance bioavailability, fluorocarbons, and/or other solubilizing or dispersing agents known in the art.

[0107] The IgNARs and VNA_RS of the present invention may also be administered in intravenous (both bolus and infusion), intraperitoneal, subcutaneous, topical with or without occlusion, or intramuscular form, all using forms well known to those of ordinary skill in the pharmaceutical arts. When administered by injection, the injectable solutions or suspensions may be formulated according to known art, using suitable non-toxic, parenterally-acceptable diluents or solvents, such as mannitol, 1,3-butanediol, water, Ringer's solution or isotonic sodium chloride solution, or suitable dispersing or wetting and suspending agents, such as sterile, bland, fixed oils, including synthetic mono- or diglycerides, and fatty acids, including oleic acid.

[0108] Administration and/or formulation may also involve the use of nanocapsules or other forms of nano-formulations.

[0109] When rectally administered in the form of suppositories, these compositions may be prepared by mixing the drug with a suitable non-irritating excipient, such as cocoa butter, synthetic glyceride esters or polyethylene glycols, which are solid at ordinary temperatures, but liquidity and/or dissolve in the rectal cavity to release the drug.

[0110] The effective dosage of the agents employed in anti-HBV therapy may vary depending on the particular compound employed, the mode of administration, the symptoms being treated and the severity or stage of the HBV infection being treated. Thus, the dosage regimen utilizing the compounds of the present invention is selected in accordance with a variety of factors including type, species, age, weight, sex and medical condition of the patient; the severity of the condition to be treated; the route of administration; the renal and hepatic function of the patient; and the particular compound thereof employed. A physician, clinician or veterinarian of ordinary skill can readily determine and prescribe the effective amount of the drug required to prevent, counter or arrest the progress of the condition. Optimal precision in achieving concentration of drug within the range that yields efficacy without toxicity requires a regimen based on the kinetics of the drug's availability to target sites. This involves a consideration of the distribution, equilibrium, and elimination of a drug.

[0111] The terms "compound", "active agent", "pharmacologically active agent", "medicament", "active" and "drug" are used interchangeably herein to refer to an IgNAR or V_NA_R specific for or which binds to an HBeAg or HBcAg or precursor, processer or fragment form thereof that induces a desired pharmacological and/or physiological effect such as reducing the effects of an HBeAg or HBcAg. The terms also encompass pharmaceutically acceptable and pharmacologically active ingredients of those active agents specifically mentioned herein including but not limited to salts, esters, amides, prodrug, active metabolites, analogs and the like.

[0112] The present invention contemplates, therefore, agents useful in targeting HBeAg or HBcAg or precursors, processed or fragment forms thereof. The agents have an effect on reducing levels or activity of HBeAg or HBcAg to, for example, restore innate immunity.

The present invention extends to combinations of agents. A "combination" also includes a two-part or more such as a multi-part pharmaceutical composition where the agents are provided separately and given or dispensed separately or admixed together prior to dispensation.

[0113] The terms "effective amount" and "therapeutically effective amount" of an agent as used herein mean a sufficient amount of the agent to provide the desired therapeutic or physiological effect such as restoration of innate immunity levels, clearance of HBV, reduction in the symptoms of chronic HBV infection and the like.

[0114] By "pharmaceutically acceptable" carrier, excipient or diluent is meant a pharmaceutical vehicle comprised of a material that is not biologically or otherwise undesirable, i.e. the material may be administered to a subject along with the selected active agent without causing any or a substantial adverse reaction. Carriers may include excipients and other additives such as diluents, detergents, coloring agents, wetting or emulsifying agents, pH buffering agents, preservatives, and the like.

[0115] Similarly, a "pharmacologically acceptable" salt, ester, emide, prodrug or derivative of a compound as provided herein is a salt, ester, amide, prodrug or derivative that this not biologically or otherwise undesirable. [0116] The terms "treating" and "treatment" as used herein refer to reduction in severity and/or frequency of symptoms, elimination of symptoms and/or underlying cause, prevention of the occurrence of symptoms and/or their underlying cause, and improvement or remediation of damage. Thus, for example, "treating" a patient having or suspected of having HBV infection involves prevention of a particular disorder or adverse physiological event in a susceptible individual as well as treatment of a clinically symptomatic individual by inhibiting or causing regression of an HBV related condition. Treatment also involves the administration of IgNAR for an extracellular target or providing it in a form which enables it to be produced in a cell or to enter a cell to target an intracellular target.

[0117] "Patient" as used herein refers to an animal, preferably a mammal and more preferably human who can benefit from the pharmaceutical formulations and methods of the present invention. There is no limitation on the type of animal that could benefit from the presently described pharmaceutical formulations and methods. A patient regardless of whether a human or non-human animal may be referred to as an individual, subject, animal, host or recipient. The compounds and methods of the present invention have applications in human medicine, veterinary medicine as well as in general, domestic or wild animal husbandry. For convenience, an "animal" includes an avian species such as a poultry bird, an aviary bird or game bird.

[0118] The particular animals contemplated herein are humans or other primates, livestock animals, laboratory test animals, companion animals or captive wild animals. Generally, the subject is a human.

[0119] The IgNAR/V_NAR immunoglobulins of the present invention are referred to herein as "primary immunoglobulins". The present invention extends however to secondary immunoglobulin molecules specific for or which bind to the IgNAR/V_NAR molecules which in turn are specific for or which bind HBeAg and/or HBcAg or a precursor or processed form thereof. Such secondary immunoglobulins are useful for detecting binding events between an IgNAR or VN_AR and HBeAg and/or HBcAg or their precursor or processed forms. The secondary immunoglobulins may also be used in affinity purification protocols of the primary immunoglobulins.

[0120] The primary and secondary immunoglobulins are particularly useful in diagnostic assays for the early and rapid detection of HBeAg and/or HBcAg and in particular intracellular forms thereof.

[0121] The secondary immunoglobulins may be an IgNAR or a polyclonal or monoclonal antibody. Monoclonal antibodies for use in an immunoassay are particularly preferred because of the ability to produce them in large quantities and the homogeneity of the product. The preparation of hybridoma cell lines for monoclonal antibody production is derived by fusing an immortal cell line and lymphocytes sensitized against the immunogenic preparation (i.e. comprising 35-LM polypeptide) or can be done by techniques which are well known to those who are skilled in the art. (See, for example, Douillard and Hoffman, Basic Facts about Hybridomas, in Compendium of Immunology Vol. II, ed. by Schwartz, 1981; Kohler and Milstein, Nature 256: 495-499, 1975; Kohler and Milstein, European Journal of Immunology 6: 511-519, 1976). Single chain antibodies or transgenic mice expressing humanized antibodies or other recognition proteins may also be used. Useful proteins in this regard include diabodies, peptide mimetics and antibody fragments such as scFv fragments and Fab fragments.

[0122] Monoclonal antibodies which bind specifically an HBeAg- or HBcAg-specific IgNAR or VN_AR provide a convenient method for detecting and targeting the IgNARs or VN_ARS. A large number of assays are available. For example, Western blotting and ELISA procedures may be employed. A wide range of immunoassay techniques are available as can be seen by reference to U.S. Patent Nos. 4,016,043, 4,424,279 and 4,018,653. These include both single-site and two-site or "sandwich" assays of the non-competitive types, as well as in the traditional competitive binding assays. These assays also include direct binding of a labeled IgNAR/V_NAR to HBeAg or HBcAg or indirect via a labeled secondary immunoglobulin specific for the IgNAR/VNAR. [0123] In one exemplary ELISA, recombinant HBeAg or HBcAg or precursor or processed forms thereof or fragments thereof are immobilized or otherwise coated on a solid support. The immobilized proteins are then contacted with a labeled IgNAR or VNAR and directed binding detected or contacted with unlabeled IgNAR or VN_AR and binding detected by a secondary labeled antibody specific for the IgNAR or VN_AR or competition binding between IgNAR or VN_AR and another anti-HBeAg or anti-HBcAg.

[0124] In addition, the assays may be part of a therapeutic protocol where a therapy is monitored for levels of HBcAg. A change, for example, from an interferon to a nucleoside or nucleotide analog or from one nucleoside or nucleotide analog to another may be recommended if there is seroconversion to HBeAg^+ve or if there is no reduction in HBeAg^+ve levels.

[0125] The present invention is further described by the following non-limiting Examples. Materials and methods employed in these Examples are provided herein under.

PreCore and Corei₄₉ Protein Expression and Purification

[0126] Full-length HBeAg and C-terminally truncated HBcAg (149 residues) were cloned into the pGEX-6-1 vector (Amersham, Uppsala, Sweden), from the reference genotype D clone of HBV (Delaney and Isom, Hepatology 25:1134-1146, 1998). Protein expression was induced with ImM IPTG (Isopropyl-beta-D-thiogalactoside; ScimaR, Australia) in BL21(DE3) E.coli host cells (Novagen, Madison, WI, USA). Soluble recombinant protein was purified on glutathione sepharose 4B beads (Amersham). Fusion proteins were either competitively eluted from the glutathione sepharose with 1OmM reduced glutathione (Roche, Indianapolis, IN, USA), or recombinant HBeAg or HBcAg cleaved from the GST fusion tag using PreScission protease (Amersham). Purified recombinant protein was dialyzed into PBS or 10-5OmM Tris pH7.0-7.5 and concentrated. Purity was assessed by SDS-PAGE followed by Coomassie staining and Western blotting (WB); by FPLC analysis using either a superdex75 or a superoseό column (Amersham), and by N-terminal protein sequencing. [0127] Mammalian expression of HBeAg and HBcAg was accomplished using stably and transiently transfected expression constructs. Cell lysates and culture supernatant of Huh-7 cells stably transfected (constitutively expressing) with pTRE-core (HBcAg), pTRE- PreCore (HBeAg) or empty vector control were harvested as previously described (Visvanathan et al, 2005 supra). Transiently transfections of Huh-7 cells with pCI-core, pCI-PreCore or pCI empty vector control using FuGeneβ reagent (Roche) in OPTI-MEM media (Invitrogen, Carlsbad, CA, USA) were maintained for 5 days before the cell lysates and culture supernatant were harvested.

Phage Library Panning

[0128] Construction of the Wobbegong (Orectolobus maculatus) VN_AR library has been described previously (Nuttall et al, 2003 supra). The total library size was ~4.0 x 10 independent clones. Phagemid particles carrying the V_NAR-gene3 protein were propagated and isolated by standard procedures. For bioparming of the phagemid library, recombinant HBeAg (1.25-3.75 μg/ml in PBS) was coated onto Maxisorb Immunotubes and incubated at 4⁰C overnight. Immunotubes were rinsed (PBS), blocked with PBS/2% w/v Blotto (Skim milk powder, Diploma, Australia) for 2h at room temperature (RT), rinsed (PBS) and incubated with freshly prepared phagemid particles (in PBS/2% w/v Blotto) for 30 min at RT with gentle agitation followed by 90 min without agitation. After incubation, immunotubes were washed (PBS/0.05% v/v Tween20; 10-20 washes), followed by an identical set of washes with PBS. Phagemid particles were eluted using 2% v/v Triethylamine, neutralized by the addition of IM Tris pH7.5, and either immediately reinfected into E. coli TGl or stored at 4⁰C. Four rounds of panning were performed, with the stringency of selection increasing at each round. Following final selection, phagemid particles were infected into E. coli TGl and propagated as plasmids, followed by DNA extraction. The VNA_R cassette was extracted as a NotVSfil fragment and subcloned into the similarly restricted cloning/expression vector pGC (Coia et al, Gene 201:203-209, 1997). DNA clones were sequenced using a BigDye terminator cycle sequencing kit (Applied Biosystems, USA) and a Perkin Elmer Sequenator. Soluble expression of V_NAR monomelic and dimeric proteins

[0129] Recombinant IgNAR V_NAR protein was expressed into the E. coli periplasm as previously described (Nuttall et al, 2001 supra). Periplasmic fractions were isolated by the method of Minsky et al, Proc Natl Acad Sd USA 83:4180-4184, 1986 and either used as crude fractions or recombinant protein purified by affinity chromatography using an anti- FLAG antibody-Sepharose column. Recombinant V_NAR protein was eluted with Immunopure (Registered trade mark) gentle elution buffer (GEB; Pierce, Rockford, IL, USA), dialyzed into PBS or 1OmM Tris pH7.0-7.5, and concentrated by ultrafiltration over a 3kDa cut off membrane (YM3; Diaflo, Millipore, MA, USA). Protein purity was analyzed by SDS-PAGE using 12.5% Tris/glycine gels; and by size exclusion gel chromatography (FPLC) through a calibrated Superdex 75 HR 10/30 columns (Amersham).

Biosensor binding analysis [0130] Surface plasmon resonance (SPR) measurements were performed using a Biacore TlOO biosensor system (Biacore AB, Uppsala, Sweden). CM5 sensor chips, 10x HBS-EP+ buffer, mouse anti-GST IgG antibody (α-GST), amine coupling kit containing 1 -Ethyl 3- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), N-hydroxysuccinimide (NHS) and IM ethanolamine hydrochloride, pH8.5 were obtained from Biacore AB. All experiments were performed at 25⁰C using a continuous flow in filtered Ix HBS-EP+ buffer (1OmM HEPES, 15OmM M NaCl, 3mM EDTA, 0.05% v/v surfactant P-20, pH 7-4).

[0131] Analysis of the interaction between the VNA_R proteins and HBeAg or HBcAg was carried out using an indirect assay whereby HBeAg-GST or HBcAg-GST fusion protein was captured onto a sensor chip surface via α-GST antibody. A standard coupling protocol was employed to immobilize the α-GST antibody via exposed primary amines (Ferns and Tedder, J Gen Virol 65(Pt 5j:899-908, 1984) in two separate flow cells (1 and 2). "Aim- for-immobilized-level" wizard template available within Biacore TlOO Control software (version 1.1) was utilized for the two separate immobilizations. Briefly, the carboxyl groups on the sensor surface in flow cell 1 (reference surface) and 2 were activated by a 7 ^• min injection (lOμl/min) of a freshly prepared l:l,200mM EDC:50mM NHS. Then small volumes (l-9μl) of α-GST (30μg/ml, 1OmM sodium acetate pH5.0) were automatically injected at 5μl/min until immobilization of approximately 4000 RU of antibody was reached. The immobilization procedure was completed by a 7 min injection (lOμl/min) of IM ethanolamine (pH8.5) to deactivate residual reactive sites.

[0132] HBeAg-GST or HBcAg-GST samples (20μg/ml) were injected for 3 min at a flow rate of 30μl/min over α-GST surface in flow cell 2 resulting in a capture of approximately 264.5±12.4 RU of recombinant protein. V_NA_R proteins spanning, 26.25 to 42OnM in concentration, were injected serially over the antibody and reference surfaces at a flow-rate of 30μl/min. Association and dissociation phases were each monitored for lOmin. At least one buffer only injection identical to V_NA_R injections was included for the purpose of double-referencing. The V_NA_R and antigen surfaces were regenerated within the 10 min dissociation phase. The HBeAg-GST or HBcAg-GST surfaces were regenerated between each V_NAR concentration set with a single 3 min injection of 10 mM Glycine pH 2.2. To determine the kinetic parameters of the interactions, each data set was double-referenced and fit globally to a 1:1 interaction model using Biacore TlOO evaluation software (version 1.1).

Antibodies [0133] The following primary antibodies (Ab 's) were utilized: mouse anti-FLAG monoclonal Ab (mAb) (WEHI, Australia) at 1:1000; Fitz mouse anti-HBeAg mAb (Fitzgerald, Concord, MA₅USA) at 1:4000; Prm-3 rabbit anti-HBeAg polyclonal antibody (VIDRL, Australia) produced to the 10 unique HBeAg residues [18] at 1:2000; BioD mouse anti-HBeAg mAb (Biodesign, ) at 1:1000; Dako rabbit anti-HBeAg polyclonal antibody (Dako, ) at 1:10000; and e2 (1:60000), e6 and e9 (1:100000) mouse anti-HBeAg mAb.

[0134] The following horseradish peroxidase (HRP)-conjugated secondary antibodies were utilized at 1:2000: goat anti-mouse immunoglobulin (Ig) (Pierce); goat anti-rabbit HRP IgG H+L (Biorad, Hercules, CA, USA); rabbit anti-mouse IgG (Dako); and mouse anti- Flag M2 IgG (Sigma, St Louis, USA). ELISA

[0135] For standard immunoassays recombinant proteins (0.4μg/well) in PBS were coated onto Maxisorb Immuno-plates (Nunc, Germany) and incubated at RT overnight. Plates were rinsed, blocked with PBS/5% w/v Blotto for Ih, rinsed with PBS, and incubated with periplasmic fractions or recombinant protein for Ih at RT. Plates were twice rinsed with PBS, washed once with PBS/0.05% v/v Tween20, and primary antibody (either anti-FLAG or Fitz anti-HBeAg) in PBS/5% w/v Blotto added. Plates were incubated and washed as above, and the GaR or GaM HRP conjugated secondary antibody added (in PBS/5% w/v Blotto). Plates were washed again, developed using ABTS (2,2 azino di-(ethyl) benzthiazoline sulphonic acid [Roche, Germany]), and read at A_4O5nTn. For competition immunoassays, modifications applied as follows. HBeAg was coated to the plate at 0. lug/well, and detected by H6 VN_AR at 0.2ug/well alone, or by H6 VNA_R in competition with other anti-HBeAg antibodies (Prm3, BioD, Dako, e2, e6, e9), followed by anti-Flag HRP secondary antibody.

Peptide Library Construction and ELISA

[0136] A peptide library of 49 peptides covering the HBeAg (159 residues) in 15mer peptides with a 12-residue overlap was constructed by Mimotopes, Australia. The peptides were produced with an N-terminal Biotin tag, and C-terminal amide, and were reconstituted in DMSO (Sigma) at lmg/ml, prior to dilution in PBS for immunoassays. Biotinylated peptides (100ng/well) were bound to Elisa plates (Griener, ) that had been coated with 500ng/well streptavidin, blocked with 1% BSA for lhr and rinsed in triplicate with PBS/0.05% Tween20. Elisa plates were rinsed six times with PBS/0.05% TweerώO between every other step. Primary antibody (H6 VNA_R at 0.2ug/well) or control antibody (non-specific control VNAR at 0.2ug/well) were incubated on the plate for lhr. Detection was by secondary anti-Flag HRP antibody and ABTS substrate development read at

A₄OSnIiV EXAMPLE 1 Isolation ofHBVHBeAg/HBcAg antigen specific IgNAR variable domain

[0137] The HBeAg is a non-structural viral protein of 159 residues (~18kDa) produced by HBV, for which 149 residues are identical to the HBcAg (183 residues, ~21kDa) viral capsid protein (Figure. 1). Recombinant HBeAg target protein was expressed and purified in E. coli. To identify novel single-domain binding reagents against HBeAg, a bacteriophage library displaying IgNAR variable domains (VN_ARS) was screened against the HBeAg. This VNAR library contained ~4 x 10 independent clones displayed as a fusion with the gene3 protein of fd bacteriophage in the vector pFAB5c.HIS, allowing for standard phage display and selection. Variability is largely targeted within the long VN_AR CDR3 loop (15-18 residues), and to a lesser extent within the CDRl and framework regions (Nuttall et al, 2003 supra).

[0138] The V_NAR library was transformed into E. coli TGl and phagemid particles rescued and panned against the immobilized HBeAg. Four rounds of biopanning were performed with increasing stringency, and between selection rounds three and four, an increase (~100-fold) in the titre of eluted bacteriophage was observed. Colony PCR on transfected bacteriophage showed that 100% of colonies were positive for VN_AR sequences and this combined with the increase in the titre, indicated positive selection. Thus, V_NA_R cassettes were rescued from phagemids, subcloned into the periplasmic expression vector pGC, and transformed into E. coli TGl. Periplasmic fractions from recombinant clones were tested for binding to HBeAg and control antigens by ELISA. A group of similar clones showed marked binding above background, and upon further analysis, all could be classified into one of two sequence types, differing at only 4 residues. Of these, the clones designated H6 and H3, which represented the two identified sequence types, were selected for further analysis.

[0139] The deduced amino acid sequences of VNA_R clones H6 and H3 are presented in Figure 2 A, including in-frame dual octapeptide FLAG epitope tags and two alanine linker regions. The protein sequences revealed typical V_NAR domains of 113 residues, with large (18 residue) CDR3 loops and an invariant disulphide bridge (Cys²²-Cys⁸³) connecting the two β-sheets that is typical of the immunoglobulin fold. There is also two further cysteine residues within the CDRl to CDR3 loop regions (Cys²⁹ & Cys⁹⁵) consistent with formation of an interloop disulphide bridge (Streltsov et al, 2005 supra). Dominant selection of just two clones after four rounds of biopanning represents a high enrichment factor (>10⁸). Such positive selection may be due to high affinity for the target antigen, and/or by a competitive advantage provided by superior expression qualities of the selected proteins. Interestingly, the sequence of residues at the framework CDR3 junction (residues 83-85), suggest that this family derived from the native shark repertoire (Dooley and Flzjnik, Dev Comp Immunol 30:43-56, 2006).

[0140] When expressed in E. coli and purified by affinity chromatography using α-FLAG antibody, expression levels of between 2-3mg/L were routinely obtained for both H6 and H3 VN_ARS. This protein was predominantly in the monomelic state, as identified by size exclusion chromatography (Figures 2B and C), where a single peak eluted at -29 min from a pre-calibrated Superdex 75 gel filtration column, corresponding to a protein of ~14.7kDa, and consistent with the size of the monomelic VN_AR domain. (Figures 2B and C). Analysis by dynamic light scatter indicated a degree of weak association of H6 V_NAR in solution that was easily disrupted by weak detergent (1% v/v Tween20), or the gel filtration conditions, as above (Figures 2B and C). This multimeric form appears similar to that observed previously for several VNA_R domains, occurring across the C & D strands in the absence of an extended CDR2 loop (Streltsov and Nuttall, Immunol Lett P7:159-160, 2005). The H6 and H3 protein expression characteristics and size exclusion chromatography profiles were almost identical, emphasizing the similarity of the two proteins (Figures 2B and C).

[0141] The specificity of V_NA_R H6 was demonstrated by ELISA (Figure. 2D). The H6 V_NA_R recombinant protein displayed strong recognition for HBeAg, and exhibited weak cross-reaction for HBcAg, indicating that the VNA_R binding site lies within the 149 residues that are common to both HBeAg and HBcAg. (Figure. 2D). Non-specific affinity was not observed, with no binding response for H6 to either GST (AtQ_Snm 0.04) or lysozyme (Arøs_nm 0.08) negative control antigens. Furthermore, non-specific IgNAR binding to HBeAg or HBcAg was not apparent, a control VNA_R domain (a non-specific library clone) failed to display any response for HBeAg or HBcAg (A_405H1n 0.01±0.004 and O.Oό±O.Ol respectively). The H6 VNAR recognized both HBeAg and HBcAg, however the response was more dominant for HBeAg (A_4OSnn, 1.96±0.1) compared with HBcAg (A_405nIn 0.53±0.04), probably due to slight variations in the structural conformation of HBeAg compared with HBcAg mediated by the unique N-terminal 10 residues.

EXAMPLE 2 BIAcore binding affinity analysis

[0142] To determine the H6 and H3 V_NAR binding kinetics, HBeAg and HBcAg GST-tag fusion proteins were captured to an α-GST surface. This configuration correctly orientated the HBeAg and HBcAg on the chip for surface plasmon-resonance (SPR) measurements (in triplicate) of binding interactions with the V_NAR domain analytes. Consistent with the ELISA findings, the V_NARS H6 and H3 displayed binding recognition for HBeAg and HBcAg target proteins. Analysis of the binding data with the 1:1 Langmuir binding model showed a good fit for the monovalent analyte (H6 or H3) binding to an HBeAg/HBcAg epitope consistent with a 1:1 binding interaction (Figure 3). There was no binding of the H6 or H3 monomer to a blank surface (activated and then blocked with ethanolamine) indicating that non-specific interaction with the sensor surface was not occurring.

[0143] The binding reaction pattern indicated rapid association of VNA_R H6 (or H3) with HBeAg and HBcAg to reach reaction equilibrium, which was followed by rapid dissociation (Figure 3). The rapid realization of reaction equilibrium allowed for determination of affinity by equilibrium parameters in addition to kinetic parameters. The various binding affinities and reaction rates are summarized in Table 4. Significant observations include: (i) the highest affinity (53nM) was between H6 and HBeAg (Figure 3A); (ii) the affinity (9OnM) between H6 and HBcAg was 1.7-fold weaker (Figure 3B); (iii) V_NAR H3 had 2-fold weaker affinity (105.5nM) for HBeAg (Figure 3C) and 1.6 fold weaker affinity (146nM) for HBcAg (Figure 3D) than H6 affinities. The variation in binding affinity between VN_ARS H6 and H3 must be due to the 4-residue variation, with the H6 sequence allowing for slightly better access to the binding recognition site of both HBeAg and HBcAg. Furthermore, both the H6 and H3 binding data consistently indicated an increased affinity for HBeAg compared to HBcAg. it is proposed herein that the V_NARS interact with the same epitope on HBeAg and HBcAg, but that this epitope is better displayed by HBeAg due to minor structural variations in protein folding influenced by the 10 unique residues at the N-terminus.

EXAMPLE 3 Detection of native antigen by V_NAR H6

[0144] The VN_AR library was selected against immobilized purified recombinant HBeAg expressed and purified from BL21(DE3) E.coli. In order to test whether the resulting binding V_NAR domains could bind to native (mammalian cell produced) HBeAg and HBcAg, the strongest binding V_NA_R (H6) was tested for recognition of HBeAg and HBcAg produced by dual mammalian expression systems using pCI-Huh7 or pTRE-Huh7 cell lines expressing either PreCore precursor/HBeAg or HBcAg. H6 was immobilized, and the binding of HBeAg and HBcAg present in cell lysates and supernatant fractions determined by ELISA (Figure 4). VNA_R H6 bound HBeAg and HBcAg exported to the supernatant of Huh-7 cell cultures stably transfected and constitutively expressing from pTRE- core/PreCore constructs (A_40Sm11 0.32±0.04 and 0.28±0.03 respectively, normalized to PBS) but not to cell lysate samples or pTRE empty vector control samples (Figure. 4). Furthermore, HBeAg was detected in the cell lysate (A^_nm 0.62±0.14) and culture supernatant (Arøs_nm 0.15±0.05) of Huh-7 cells that were transiently transfected with pCI- PreCore constructs. There was no recognition of core or empty vector control cell lysate or culture supernatant samples (Figure 4). Aggregation of overexpressed protein in the pCI transiently transfected Huh-7 cells, appeared to favor the cellular retention rather than secretion of HBeAg, while HBcAg may be undetectable in a highly aggregated format. Thus, the H6 VNA_R is capable of recognizing HBeAg and HBcAg produced in mammalian cell culture, which is more closely indicative of native protein in terms of structure and processing in comparison to bacterially produced protein (possibly deficient in higher order protein processing and folding). These results indicate that VNA_R H6 is suitable for diagnostic purposes to recognize HBeAg/HBcAg from clinical samples.

EXAMPLE 4 Epitope Mapping of VN_AR H6

[0145] The H6 V_NA_R was hypothesized to bind a conformation epitope, based on previous publications that suggest the extended V_NAR CDR3 loop enables access to cryptic antigen pockets (Greenberg et al, 1995 supra; Ewert et al, 2002 supra; Nuttall et al, 2004 supra; Stanfield et al, 2004 supra; Streltsov et al, 2004 supra; Streltsov et al, 2005 supra). The H6 V_NAR recognition epitope was therefore expected to be unique in comparison to the majority of tradition anti-HBeAg/HBcAg antibodies that target the linear epitope of the immundominant loop (residues 70-85) at the tip of the dimer/capsid spike. When the H6 V_NAR was incubated in competition with several anti-HBeAg/HBcAg antibodies to bind immobilized HBeAg, the binding of H6 VNA_R to HBeAg was found to be unaffected. Binding recognition was equivalent or slightly improved in comparison to the binding of the H6 VN_AR alone to HBeAg (Figure 5). This suggests that the H6 V_NA_R is recognizing HBeAg via a alternative epitope to the other tested antibodies, and further that the H6 V_NA_R epitope is not obscured by binding proximity of each of the competing antibodies. Therefore, the H6 VNA_R epitope is not the linear epitope of the immunodominant loop. Neither does the H6 V_NAR recognize the 10 HBeAg unique N-terminal residues, with no competition binding effect observed with Prm3 antibody. This result was consistent with the H6 V_NA_R cross-reactivity for HBcAg.

[0146] Peptide library mapping of the H6 V_NAR for HBeAg overlapping linear epitopes confirmed recognition via a conformational epitope. The H6 V_NAR displayed no specific recognition for any of the HBeAg peptides. A non-specific response was apparent to peptides 34-36, corresponding to HBeAg residues 100-120, which was identical to the non-specific control V_NA_R response (Figure 6). The reactive peptides (34-36) possess a hydrophobic residue bias, which based on previous VNA_R studies, can present a nonspecific binding motif for the typical residues of VNA_R'S framework regions. Table 4 -Average affinity oflgNAR's H6 and H3 for target antigens

Target Ag IgNAR K_a K_ri Kinetic Equilibrium Overall

(WI-¹S-¹) (S-¹; K_D(nM) K_D(nM) K_D(nM)

H6 1.25±0.15x10⁶ 6.07±0.31x10^"2 49 57 53 ±5.7

HBeAg

H3 8.61 +0.88x10⁵ 8.76+1.66x10-² 101 110 106 +6.6

H6 1.48+0.22x10⁶ 10.8±0.55x10-² 74 105 90 ±22

HBcAg

H3 1.01 ±0.89x10⁵ 14±1.07x10"² 140 152 146 ±8.7

EXAMPLE 5

Targeting ofPreCore and Core antigens

[0147] IgNAR intrabodies were expressed in cells. Western Blot analysis of PreCore (pc47) and core (C4B) stable expressing cell lines transfected with intrabody construct (MB) in comparison to non-transfected controls is shown in Figure 7. Expression of the H6 intrabody (MB) incorporating ER signal and retention peptides (and a double FLAG tag) was detected in both cells lines in comparison to non-transfected control cells. The H6 intrabody is apparent as a doublet band, indicative of ER processing resulting in H6 intrabody possessing both ER signal and retention peptides (higher band), and H6 intrabody with the ER signal peptide removed (lower band). H6 intrabody was visualized using anti-FLAG HRP antibody [Sigma].

[0148] Figure 8 shows stable PreCore (pc47), core (C4B) and control (pTRE) cell lines transfected with anti-HBe H6 intrabody (MB) construct incorporating ER signal and retention peptides, in comparison to non-transfected and mock controls. Figure 8 (A) shows Western Blot detection of intracellular (in the lysate [lys]) and extracellular (in the supematant [sn]) PreCore and core protein using a monoclonal anti-HBe/c antibody (1D8). Figure 8 (B) shows densitometry analysis of PreCore and core protein expression detected by Western Blot. The expression of PreCore or core protein was determined relative to non-transfected treatment controls. Intracellular PreCore protein (p25e) was decreased in mock treatment controls (69% of non-transfected), and further by the H6 intrabody treatment (58% of non-transfected). The secretion of extracellular PreCore or HBeAg (ρl7e) was regulated by the H6 intrabody to just 17% in comparison to non-transfected and mock (87%) treatments. Core protein (p21) which is not expected to be secreted, was present only intracellularly, and expression levels were unaffected by H6 intrabody treatment or mock control transfection in comparison to non-transfected cells. The control pTRE cell line did not produce PreCore or core protein, as expected. These data indicate that the H6 intrabody is having an effect to prevent/regulate PreCore or HBeAg (pl7e) secretion into the supernatant. The H6 intrabody is targeted to the ER where the PreCore protein is processed N- and C- terminally from p25e to pl7e, the extracellular form of the protein that is secreted from the cell. The H6 intrabody will bind and retain PreCore protein in the ER, which will reduce PreCore or HBeAg (pl7e) secretion, and furthermore the bound PreCore protein will enter ER or proteasome degradation pathways to circumvent a toxic intracellular accumulation of PreCore protein.

[0149] Stable PreCore (pc47), core (C4B) and control (pTRE) cell lines were transfected with anti-HBe H6 intrabody (IntB) construct incorporating ER signal and retention peptides, in comparison to non-transfected and mock controls. The results are shown in Figure 9. The expression of PreCore or core protein was measured by quantitative Architect ELISA assay in PEIU/ml. The PreCore protein is expected to be present at low levels intracellularly (in the lysate [lys]), whilst most PreCore protein is expected to be secreted into the supernatant (sn), which was observed. Transfection of ρc47 PreCore expressing cells with H6 intrabody resulted in 34 PEIU/ml intracellular PreCore (p25e), a reduction compared to non-transfected (94 PEIU/ml) and mock (79 PEIU/ml) controls. The levels of secreted extracellular PreCore or HBeAg (pl7e) were more significantly regulated by H6 intrabody treatment to 67 PEIU/ml compared to non-transfected (359 PEIU/ml) and mock (395 PEIU/ml) controls. Core protein (p21) which is not secreted (undetectable levels), was detected intracellularly only, and expression levels were detected at 434 PEIU/ml in the H6 intrabody treated cells, a reduction in comparison to non-transfected (832 PEIU/ml) and mock (745 PEIU/ml) controls. The control pTRE cell line did not produce PreCore or core protein (undetectable levels), as expected. These data further indicate that H6 intrabody acts to reduce both intracellular PreCore protein (through ER retention and degradation pathways) and more importantly extracellular secreted PreCore or HBeAg protein. In addition this data suggests the H6 intrabody also has an effect in reducing intracellular core protein, likely though re-localisation to the ER and degradation.

[0150] This Example shows the following:

1. The H6 intrabody is expressed in the stable PreCore (pc47) and core (C4B) hepatocyte expression cell lines.

2. Both intracellular and extracellular PreCore proteins are reduced by actions of the H6 intrabody.

3. Intracellular core protein is also reduced by H6 intrabody.

4. The H6 intrabody, targeted to the ER, binds intracellular PreCore (and core) protein. This is expected to prevent PreCore processing and secretion, and furthermore to induce processing through the ER or proteasome degradation pathways to avoid potentially toxic intracellular accumulation of PreCore protein.

5. The anti-HBe H6 intrabody is capable of regulating extracellular PreCore protein levels. This enables development of a therapeutic antibody to regulate PreCore protein, which is hypothesized to dampen the tolerogenic effect of PreCore protein on the immune system and also to increase the effectiveness of current antiviral treatments (such as IFN) that are susceptible to HBeAg titre. This interrupts the progression to chronic hepatitis B (CHB) and the major clinical outcomes of liver cirrhosis and hepatocellular carcinoma (HCC). [0151] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any two or more of said steps or features.

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Claims

CLAIMS:

1. An isolated cartilaginous marine animal-derived immunoglobulin-like molecule which binds to human hepatitis B e antigen (HBeAg) and/or human hepatitis core antigen (HBcAg) or a precursor or processed form thereof or a fragment thereof.

2. The isolated immunoglobulin-like molecule of Claim 1 wherein a precursor form of HBeAg or HBcAg is in an intracellular form.

3. The isolated immunoglobulin-like molecule of Claim 2 wherein the HBeAg precursor is p22^e or p25^e.

4. The isolated immunoglobulin-like molecule of Claim 1 or 2 or 3 which binds to both HBeAg and HBcAg or a precursor or processed form thereof or a fragment thereof.

5. The isolated immunoglobulin-like molecule of Claim 4 wherein the HBeAg and HBcAg are in intracellular forms.

6. The isolated immunoglobulin-like molecule of Claim 1 wherein the cartilaginous marine animal is a shark.

7. The isolated immunoglobulin-like molecule of Claim 6 wherein the molecule is an IgNAR or a portion thereof.

8. The isolated immunoglobulin-like molecule of Claim 6 or 7 wherein the molecule is a VMAR.

9. An isolated VNAR derived from a shark which binds to an HBV antigen selected from the list consisting o:

(i) an HBeAg or a precursor or processed form thereof; (ii) an HBcAg or a precursor or processed form thereof;

(iii) HBeAg and HBcAg or a precursor or processed form thereof.

10. The isolated V_NAR of Claim 9 comprising an amino acid sequence selected from SEQ ID NO:1 and SEQ ID NO: 2 or an amino acid sequence having at least 80% similarity to SEQ ID NO:1 or SEQ ID NO:2.

11. An isolated immunoglobulin which binds to an immunoglobulin-like molecule of any one of Claims 1 to 8 or a V_NAR of Claim 9 or 10.

12. The immunoglobulin-like molecule of any one of Claims 1 to 8 or a VN_AR of Claim 9 or 10 or an immunoglobulin of Claim 11 conjugated to a reporter molecule capable of providing an identifiable signal.

13. A method for the treatment or prophylaxis of HBV infection said method comprising administering to a subject an effective amount of an IgNAR or VN_AR which binds to or is specific for HBeAg or HBcAg or a precursor or processed form thereof.

14. A therapeutic monitoring protocol in the treatment of HBV said protocol comprising treating a subject infected with HBV with an anti-viral agent and monitoring the levels of intracellular HBeAg via an immunoglobulin-like molecule of any one of Claims 1 to 8 or a V_NA_R of Claim 9 or 10 or an immunoglobulin of Claim 11 or 12.

15. An assay to detect an intracellular form of HBeAg said assay comprising contacting an immunoglobulin-like molecule of any one of Claims 1 to 8 or an isolated VN_AR of Claim 9 or 10 with cells putatively infected with HBV or a lysate thereof and screening for the formation of a complex between the immunoglobulin-like molecule or the V_NAR and the HBeAg.

16. The assay of Claim 15 wherein the HBeAg is p22^e or p25^e.

17. The assay of Claim 15 or 16 wherein the complex is detected by binding of a labeled secondary antibody to the immunoglobulin-like molecule.

18. A therapeutic monitoring protocol in the treatment of HBV said protocol comprising treating a subject infected with HBV with an anti- viral agent and monitoring the levels of intracellular HBeAg via the assay of any one of Claims 15 to 17.

19. Use of cartilaginous marine animal-derived immunoglobulin-like molecule which binds to human hepatitis B e antigen (HBeAg) and/or human hepatitis core antigen (HBcAg) or a precursor or processed form thereof or a fragment thereof in the manufacture of a medicament for the treatment or prophylaxis of HBV infection.

20. Use of cartilaginous marine animal-derived immunoglobulin-like molecule which binds to human hepatitis B e antigen (HBeAg) and/or human hepatitis core antigen (HBcAg) or a precursor or processed form thereof or a fragment thereof in the manufacture of a medicament to enhance innate immunity.

21. A kit comprising a cartilaginous marine animal-derived immunoglobulin-like molecule of any one of Claims 1 to 8 or an isolated V_NAR of Claim 9 or 10.