ABSTRACT
Hepatitis B core antibodies (anti-HBc) appear very early during the course of the hepatitis B virus infection and often persist years after viral clearance. In order to characterize the immunodominant domain of the HBcAg, the human immune response against the HBV nucleocapsid (HBcAg) was analyzed by using 14 synthetic peptides. Anti-HBc antibodies were detected by an indirect enzyme-linked immunosorbent assay (ELISA) with HBc peptides. Results suggest that the anti-HBc response is heterogeneous and directed against the whole primary structure of the HBc protein. Results also indicate that the epitopes recognized by anti-HBc antibodies can vary with the stages of the disease. In most sera from patients with serological evidence of acute HBV infection, anti-HBc antibodies recognized all the HBc peptides; conversely, after the acute phase, anti-HBc antibodies recognized predominantly epitopes located within the central region of the HBc protein from residue 74 to 123. Our results suggest that the HBV core protein is made up of two antigenic regions: a major one expressing a family of immunodominant epitopes from residue 74 to 123, whereas the minor encompasses the rest of the protein. The concept of the conformational nature of the unique HBcAg determinant is discussed, suggesting numerous families of linear epitopes.
Subject(s)
Hepatitis B Core Antigens/immunology , Hepatitis B virus/immunology , Immunodominant Epitopes/chemistry , Viral Core Proteins/immunology , Amino Acid Sequence , Binding, Competitive , Capsid/immunology , Cross Reactions , Enzyme-Linked Immunosorbent Assay , Epitopes/chemistry , Hepatitis B Antibodies/blood , Hepatitis B Core Antigens/chemistry , Hepatitis B Surface Antigens/chemistry , Hepatitis B Surface Antigens/immunology , Hepatitis B e Antigens/chemistry , Hepatitis B e Antigens/immunology , Humans , Molecular Sequence Data , Peptides/immunology , Protein Conformation , Recombinant Proteins , Viral Proteins/immunologyABSTRACT
An enzyme immunoassay for the detection of total anti-HBc antibodies in undiluted serum samples was developed. This assay utilizes an anti-HBc monoclonal antibody and a recombinant HBc antigen. The results of the clinical validation are now reported. A total of 1,301 sera were tested using both the Recombinant TOTAL HBc Ab EIA and a reference assay. The specificity was evaluated on a panel of 573 normal human sera and human sera from subjects with pathological findings unrelated to a hepatitis B virus infection. The sensitivity was studied on a total of 455 sera from HBV infected patients at different stages of infection. The final results indicate 99.8% sensitivity and 99.8% specificity. In addition, 273 sera with either isolated anti-HBc antibodies or with anti-HCV antibodies were tested. The agreement between the Recombinant and the reference assay for these two populations, 96.6 and 90.1%, respectively, is discussed.
