The NCDDG/AIDS will produce biochemically and structurally defined fragments of the human immunodeficiency virus (HIV) envelope glycoprotein and epitope mapped mouse and human monoclonal antibodies in programs 1, 2, and 6. Such reagents will have demonstrated immunogenicity in the murine system. The principle purpose of this program is to characterize those produced (and defined) epitopes on gp160 which are also recognized by humans exposed to HIV. Serological responses of humans to a panel of the peptide fragments, derived from prototype HIV isolates, will be defined. Analysis will be by SDS- PAGE and modified Western blotting procedures, as well as ELISA assays in support of specific aims 1 and 2. In addition, the immunoregulatory responses of human mononuclear leukocytes exposed in vitro to the gp120/gp41 materials will be delineated. The specific aims are: (1) To determine the presence of human antibodies to the fragments of prototype HIV envelope glycoprotein, using sera from patients with symptomatic and asymptomatic HIV infection, specifically using (a) a cohort of 50 asymptomatic seropositive patients with T4 counts less than 400, followed longitudinally, and (b) a larger group of patients with AIDS, ARC and asymptomatic seropositive status for whom prevalence (cross-sectional analysis) would be determined; (2) To examine longitudinally the serological responses of the above-defined cohort (in 1,a) to isolate-specific, variable epitopes of homologous virus, using sera absorbed with prototype-derived envelope proteins and; (3) To characterize the in vitro immunoregulatory effects of the purified HIV envelope proteins. Measurements for immunostimulatory or immunosuppressive effects will include assays for proliferative responses with mononuclear leukocytes, alternation in leukocyte expression of surface markers, and leukocyte production of interleukins and interleukin inhibitors. Thus, the current studies are designed to define further the human serologic and cellular responses to HIV using structurally defined and biochemically well characterized HIV envelope protein fragments.