ISOLATION AND EPITOPE CHARACTERIZATION OF HUMAN MONOCLONAL-ANTIBODIESTO HEPATITIS-C VIRUS CORE ANTIGEN

In this study we describe the establishment of two hybridoma cell line s secreting human monoclonal antibodies to the 22-kD nucleocapsid prot ein (core, p22) of the hepatitis C virus (HCV). For this purpose we is olated B lymphocytes from an anti-HCV positive blood donor and infecte d them with Epstein-Barr (EBV). We obtained several lymphoblastoid cel l clones secreting antibodies to the recombinant HCV core protein. The B-cell cultures were oligoclonally expanded and two of them were fuse d with the (mouse:human) heteromyeloma cell line K6H6/B5. The resultin g stable hybridomas produce antibodies of the IgG1/kappa (Ul/F10) and the IgM/kappa (Ul/F11) isotype reacting specifically with the recombin ant core protein p22. To identify the epitopes recognized by these ant ibodies we synthesized overlapping peptides (13-mer and 6-mer) from th e amino terminus of the core amino acid sequence. Antibody reactivity to these peptides was analyzed in an immunoblot assay. Finally, we wer e able to define a linear epitope recognized by the Ul/F10 antibody on the nucleocapsid protein. The antibody shows specificity to the seque nce N-VYLLPR-C, which corresponds to the amino acids 34-39 of the core sequence.