The Structure of the Variable Regions of Mouse Monoclonal Antibodies to Hepatitis B Virus Core Antigen

From a panel of monoclonal antibodies (MoAbs) directed against E. coli‐derived native and denatured hepatitis B virus (HBV) core antigen we have selected a set of specific MoAbs which recognize different linear antigenic determinants: MoAb C1‐5—cl epitope; MoAb 14K8—less immunogenic N‐terminal region; and MoAbs 13C9, 10F10 and 14E11, 14G3—the immunodominant region between amino acids 134 and 140. We have applied the polymerase chain reaction technique to clone Ig VH and YL, region genes, and appropriate full‐length cDNA clones were obtained and characterized by nucleotide sequence analysis. Among the six heavy chain variable region sequences examined, three Yh families were represented. Two of them belong to the 7183 (MoAb Cl‐5) and 3609 (14B8) families respectively and four, having only two amino acid changes in the CDR2 region, to the J558 family. These four probably are derived from a single expanded B‐cell clone. The light chain sequences indicate that their YL are encoded by YK21, VK19 and YK3 germline genes. Unlike YH genes, light chain genes are closely related to known representatives of mouse kappa light chain families and are employed also by MoAbs raised against other antigens.