Antigenic sites on the arginine-rich carboxyl-terminal domain of the capsid protein of hepatitis B virus distinct from hepatitis B core or e antigen.
The capsid protein of hepatitis B virus (P19) is made of 183 amino acids and carries the antigenic sites of hepatitis B core antigen (HBcAg) and hepatitis B e antigen (HBeAg) on the amino-terminal domain. The carboxyl-terminal domain of P19 (amino acids 150-183) is arginine-rich (47%) and faces the interior of the nucleocapsid for the binding with DNA. Monoclonal antibody was raised against an antigenic site on this protamine-like region of P19, which was distinct from HBcAg or HBeAg sites, and the novel antigenic site(s) was provisionally designated as hepatitis B inner core antigen (HBicAg). When P19 in a low concn (150 ng/ml) was immobilized on the solid surface, HBicAg sites were preserved, while HBcAg or HBcAg sites were no longer available on it. This allowed the detection of antibodies against HBicAg (anti-HBic), by sandwiching them between immobilized P19 and anti-IgG labeled with horseradish peroxidase. Anti-HBic was detected in sera from HBsAg carriers, typically those seropositive for antibody to HBeAg. A synthetic arginine-rich decapeptide, with a sequence of Arg-Arg-Arg-Gly-Arg-Ser-Pro-Arg-Arg-Arg, representing amino acids 150-159 of P19 and conserved in the majority of reported hepatitis B virus, absorbed the activity to bind with P19 in seven (44%) out of 16 sera containing anti-HBic. These results indicate that the decapeptide carries an HBicAg epitope and the remaining amino acid sequence of the arginine-rich carboxyl terminal domain (160-183) may be responsible for the other HBicAg epitopes.
Machida
A
A
Section of Immunology, Kitasato Institute, Tokyo, Japan.
Ohnuma
H
H
Takai
E
E
Tsuda
F
F
Tanaka
T
T
Naito
M
M
Munekata
E
E
Miyakawa
Y
Y
Mayumi
M
M
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D001120:Arginine / Q000378:metabolism; D002213:Capsid / Q000276:immunology*; D000939:Epitopes / Q000032:analysis*; D006511:Hepatitis B Antigens / Q000276:immunology*; D006512:Hepatitis B Core Antigens / Q000276:immunology; D006513:Hepatitis B e Antigens / Q000276:immunology; D006515:Hepatitis B virus / Q000276:immunology*; D006801:Humans; D010455:Peptides
D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D000939:Epitopes; D006511:Hepatitis B Antigens; D006512:Hepatitis B Core Antigens; D006513:Hepatitis B e Antigens; D010455:Peptides; D001120:Arginine