ANTIGENIC VARIATION OF THE DOMINANT GP41-EPITOPE IN AFRICA

Objective: To determine the value of (combinations of) synthetic pepti des representing immunodominant sites on HIV-1/HIV-2 transmembrane pro teins for the detection and discrimination between HIV-1 and HIV-2 inf ection in various populations. Design and methods: Two 24-mer syntheti c peptides derived from immunodominant sites on the HIV-1 and HIV-2 tr ansmembrane proteins were used separately, in combination (env 1/2), a nd in combination with recombinant p24 (p24/env) in enzyme-linked immu nosorbent assays. Results: Positive reactions with env-1 were found in 150 out of 150 (100%) samples from Dutch AIDS patients, 60 out of 60 (100%) samples from Dutch homosexual men obtained 1 year after HIV-1-a ntibody seroconversion, 29 out of 30 (96.7%) samples from these men ob tained at the time of HIV-1-antibody seroconversion, 40 out of 41 (97. 6%) samples from East Africans with AIDS-related symptoms, and three o ut of 29 (10.3%) samples from West Africans with HIV-2 infection (incl uding a sample from an individual infected with both HIV-1 and HIV-2). Positive reactions with env-2 in these study populations were 11 out of 150 (7.3%), nine out of 60 (15%), none out of 30 (0%), 25 out of 41 (60.9%) and 29 out of 29 (100%), respectively. In the samples with du al reactivity, true versus cross-reactivity could generally be differe ntiated on the basis of large differences in optical density values in the respective assays. All samples reacted positively with p24/env; 3 08 out of 310 (99.3%) were positive in the env 1/2 assay. Four East Af rican samples that had negative or only weakly positive reactions with env-1 showed a noticeably stronger reaction with variant peptides der ived from Central African isolate sequences. In all samples from HIV-1 -infected Dutch homosexual men, the strongest signal was detected usin g the env-1 peptide sequence, which is derived from European and Ameri can isolates. Conclusions: Small peptide antigens may permit the detec tion of strain-specific antibodies, allowing serological characterizat ion of HIV isolates.