Production and characterization of a mouse monoclonal antibody against theGag p26 protein of human immunodeficiency virus type 2: Identification of a new antigenic epitope

One anticapsid (p26) mouse monoclonal antibody was developed after immuniza tion with recombinant p26 Gag protein and was tested for reactivity with di fferent HIV-1 and HIV-2 isolates by ELISA and Western blot analysis. This a ntibody, named R26.1, reacted with all HIV-2 isolates tested and with recom binant p26 proteins, but no HIV-1 isolates. The epitope of antibody R26.1 w as mapped to residues 50-71 in the N-terminal domain of the capsid protein, a highly conserved region in all HIV-2 isolates sequenced to date. This mo noclonal antibody may be useful for the detection of HIV-2, and for the dis crimination between HIV-1 and HIV-2 infections. Likewise, the identified ep itope may be useful for the detection of p26 antibodies in HIV-2-infected i ndividuals.