Discrimination of HIV-1 and HIV-2 infection based on recombinant immunoblots

Recombinant polypeptides representing various parts of structural proteins of HIV-1 and HIV-2 were expressed in E. coli. Fragments of the transmembrane proteins gp41 of HIV-1 (HTLV-IIIB) and gp38 of HIV-2 (LAV-2 ROD) proved to be highly antigenic in the immunoblot test system. Each protein was found to be suitable for detection and differentiation of antibodies in sera of patients infected with HIV-1 or HIV-2. Sera of 100 patients from West-Germany, which were confirmed as positive for HIV-1 antibodies, reacted clearly with the HIV-1 recombinant antigen (fpOE-6); no or only weak immune reactions were seen when the analogous recombinant HIV-2 antigen (fpOE-T) was used in the same immunoblot test. An inverse reaction pattern was found with 7 sera from Africa which, by conventional means, were proved to be HIV-2 antibody positive. These sera specifically reacted with the homologous HIV-2 fusion protein and no or only weakly stained bands were identified on the analogous strip with the HIV-1 antigen (fpOE-6).