Characterisation of a linear binding site for a monoclonal antibody to hepatitis B core antigen.
The complete amino acid (aa) sequence of the hepatitis B virus (HBV) core protein (HBcAg), ayw subtype, was synthesized as decapeptides with five overlapping aas. The peptides were tested for reactivity with monoclonal antibodies (mAbs) to HBcAg (35/312, 37/275, and 7/275). All the mAbs specifically inhibited human anti-HBc by cross competition in assays for anti-HBc and anti-HBe. The mAb 35/312 recognised a peptide covering residues 76-85 of the HBcAg sequence. The other two mAbs did not react specifically with any linear peptide, suggesting discontinuous epitopes for these mAbs. The linear sequence EDPASR at residues 77-82 was found to constitute the epitope for mAb 35/312 when fine mapping the binding site. The most essential aas for mAb 35/312 were found to be the DP at residues 79-80, when peptides were synthesized where the aas at 77-83, were substituted by the other 19 aas. Since the mAb 35/312 inhibits the binding of human anti-HBc positive sera, which are known to recognise an SDS labile epitope, the sequence 77-82 might be a part of a larger discontinuous epitope. Alternatively the mAb 35/312 blocks the binding of human anti-HBc by steric hindrance.
Sällberg
M
M
The National Bacteriological Laboratory, Department of Virology, Stockholm, Sweden.
Rudén
U
U
Magnius
L O
LO
Harthus
H P
HP
Noah
M
M
Wahren
B
B
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001666:Binding Sites, Antibody; D001667:Binding, Competitive; D000939:Epitopes; D006512:Hepatitis B Core Antigens / Q000737:chemistry* / Q000276:immunology; D006515:Hepatitis B virus / Q000276:immunology*; D006801:Humans; D008969:Molecular Sequence Data; D010449:Peptide Mapping
D000911:Antibodies, Monoclonal; D000939:Epitopes; D006512:Hepatitis B Core Antigens