HUMAN IMMUNODEFICIENCY VIRUS-1 (HIV-1) GP120 SUPERANTIGEN-BINDING SERUM ANTIBODIES - A HOST FACTOR IN HOMOSEXUAL HIV-1 TRANSMISSION

HIV-1 gp120 is an immunoglobulin superantigen which can bind to preimm une serum Ig. We hypothesize that levels of such preimmune antibodies vary in the population and might affect host resistance or susceptibil ity to viral transmission. This study tests two predictions: (a) level s of pre-immune anti-gp120 Igs are a polymorphic trait; and, (b) these levels are correlated with resistance or susceptibility to HIV-1 tran smission. The first prediction was confirmed in a longitudinal study o f a low-risk seronegative population. In this group, levels of both en dogenous anti-gp120 IgM and IgG varied widely, but were characteristic and stable for each individual. The second prediction was addressed i n a study of participants of the Multicenter AIDS Cohort Study, in whi ch men ''susceptible'' and ''resistant'' to HIV infection were identif ied based on numbers of sexual partners and eventual seroconversion. S pecimens consisted of archival sera obtained > 2 yr before seroconvers ion. Men in the susceptible population (low-risk seroconverters) were distinguished by low levels of anti-gp120 IgG. We conclude that the le vel of preimmune anti-gp120 IgG is a polymorphic population trait, and low levels are a potentially specific and significant factor in homos exual transmission of HIV infection.