Mapping of immunodominant B-cell epitopes and the human serum albumin-binding site in natural hepatitis B virus surface antigen of defined genosubtype.
Twelve MAbs were generated by immunization of BALB/c mice with plasma-derived hepatitis B virus surface spherical antigen particles subtype ayw2 (HBsAg/ayw2 genotype D). Their epitopes were mapped by analysis of reactivity with plasma-derived HBsAg/ayw2 and HBsAg/adw2 (genotype A) in enzyme immunoassays and blots. Mapping was supported by nested sets of truncated preS2 proteins and preS2 peptides. Five antibodies were S domain-specific, seven were preS2-specific and 11 had a preference for genotype D. According to our data, group I of the three known epitope groups of preS2 has to be divided into IA and IB. Three preS2-specific MAbs forming the new group IA reacted with genotype D residues 3-15 which have not yet been described as an epitope region. IA antibodies strongly inhibited the binding of polymerized human serum albumin. Two antibodies (group II) reacted with the glycosylated N-terminal region of preS2 in plasma-derived HBsAg, but not with a preparation from transfected murine cells. One group III antibody was subtype-specific and reacted with the highly variable preS2 sequence 38-48. Only one antibody (group IB) mapped to the region (old group I) which was believed to be immunodominant and genotype-independent. Geno(sub)type-specific epitopes of preS2 are obviously the immunodominant components of natural HBsAg in BALB/c mice, but these epitopes may be masked by serum albumins in humans. The data may explain why it is difficult to detect anti-preS2 antibodies in human recipients of preS2-containing vaccines, in spite of the preS2 immunodominance in mice.
Sobotta
D
D
Institute of Medical Virology, Clinics of the Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany.
Sominskaya
I
I
Jansons
J
J
Meisel
H
H
Schmitt
S
S
Heermann
K H
KH
Kaluza
G
G
Pumpens
P
P
Gerlich
W H
WH
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001402:B-Lymphocytes / Q000276:immunology; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D018604:Epitope Mapping; D005838:Genotype; D006031:Glycosylation; D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000276:immunology; D006515:Hepatitis B virus / Q000235:genetics* / Q000276:immunology*; D006801:Humans; D016056:Immunodominant Epitopes / Q000235:genetics; D007124:Immunoenzyme Techniques; D051379:Mice; D008969:Molecular Sequence Data; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D017386:Sequence Homology, Amino Acid; D012709:Serum Albumin / Q000378:metabolism
D000911:Antibodies, Monoclonal; D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D016056:Immunodominant Epitopes; D011498:Protein Precursors; D012709:Serum Albumin; C050807:presurface protein 2, hepatitis B surface antigen