MOLECULAR CHARACTERIZATION OF A HUMAN ANTI-HIV-1 MONOCLONAL-ANTIBODY REVEALED A CD26-RELATED MOTIF IN CDR2

Genes encoding the immunoglobulin variable regions of a human anti-HIV -1 IgG1 kappa monoclonal antibody were rescued from a hybridoma, deriv ed from a sero-negative donor, using PCR cloning and expression in Esc herichia coli. The ELISA binding results obtained from the expressed F ab fragment confirmed the anti-V3 loop specificity for HIV-1 (LAI) of the original antibody. In addition, an amino acid sequence derived fro m the second complementarity determining region (CDRH2) of the heavy c hain was found to be very similar to the catalytic motif of CD26, a T- cell activation antigen. Furthermore, synthetic peptides containing bo th the catalytic domain of CD26 and CDRH2 of the antibody showed speci fic binding to an HIV peptide representing the V3 region in a dose-dep endent manner. This suggests an involvement of CD26 as a possible core ceptor for HIV-1.