Structural base of the interaction of a monoclonal antibody against p24 of HIV-1 with its peptide epitope.

The interaction of a murine monoclonal antibody (CB 4-1) against the core protein p24 of HIV-1 with its peptide antigen was studied in detail. The amino acid sequence of the variable regions of the heavy and light chain as derived from DNA sequencing was used to model the structure of the antigen binding region on the basis of reported Fab structures from the Brookhaven Protein Data Base. A linear peptide epitope responsible for the p24 binding to the antibody was determined by peptide scan. Subsequent N- and C-terminal truncation of the corresponding sequence region as well as amino acid substitutions were performed to recognize the epitope and the amino acid residues critical for antibody binding. These data were used to derive a structural model of the peptide-antibody interaction.