Advantage of dimeric peptide antigens in serodiagnosis of HIV-1 infection.

The reactivity of antibodies with dimeric and monomeric peptide antigens was compared by ELISA. A panel of highly purified synthetic peptides of HIV-1 representing defined regions, 598-609 and 524-533 (fusion domain) of gp41 and 306-320 of gp120, were used as antigens in the ELISA. These peptides were selected and synthesized taking into account the level of sequence conservation of various strains and hydrophilicity. The analysis included sera from 52 HIV-1 infected individuals and 53 HIV-1 negative controls. Both peptides from gp41 were found to be particularly immunoreactive with sera from HIV-1 infected individuals. The frequency of reactivity to the selected peptide from gp120 (V3 loop) in infected individuals was 82%. An interesting observation was that the dimeric peptide antigens had a detection rate more than 4-fold higher than the monomeric antigens. We found that lower levels of antibodies could be detected with dimeric antigens. The peptides reacted with few sera other than HIV-1 positive sera. These results implicate the potential dimeric peptide antigens to be utilized in the serodiagnosis of HIV-1 infection.