Antibody reactivity to deletion mutants of the HIV-1 SF2 envelope

In human immunodeficiency virus type 1 (HIV-I) infected individuals, the antibody response to the external envelope (gpl20) is associated with in vitro neutralization. To further characterize the anti-gpl20 response, we examined the IgG reactivity of 75 HIV-1-seroconverted and 200 HIV-1-seropositive individuals to deletion mutants of gpl20 in an enzyme immunoassay. We used yeast-derived, non-glycosylated recombinant HIV-1 SF2 gpl20 equivalent and-variants deleted in variable regions. We observed two distinctive response patterns: IgG non-responders (SF2-V3-restricted responders) and IgG responders to conserved regions of gp!20. This divergence in response pattern occurred soon after gag/env HIV-1 antibody seroconversion and persisted in time within an individual. In addition, the SF2-V3-restricted responders had a higher frequency of HIV-1 core antigen positivity and HIV-1 core antibody negativity than the non-restricted responders. These results suggest that specific and persistent host antibody response patterns to gpl20 develop early in HIV-1 infection and that these patterns are associated with differences in HIV-1 expression.