Immune responses to a recombinant human immunodeficiency virus type 1 (HIV-1) gp160 vaccine among adults with advanced HIV infection

Objective: To assess immunogenicity of recombinant human immunodeficiency virus type 1 (HIV-1) envelope vaccine (rgp160) in late HIV infection. Study Design/Methods: HIV-infected volunteers (n = 142), with CD4(+) T lymphocyte counts of <400/mm(3), were enrolled in a dose-comparison, open-label trial with stratification by CD4(+) cell count, randomization to a primary series at two dose levels, and a sub-group receiving interferon-gamma (IFN-gamma) as an adjuvant. Subjects received booster doses of vaccine over a follow-up period of 18-28 months. Results: At 6 and 12 months, 36% and 38% of participants, respectively, had new or augmented antibody titers (greater than or equal to 4-fold increase) against one or more gp160 epitopes (C-1,V3, C-41, 448C). Delayed-type hypersensitivity (DTH) to intradermal gp160, initially not present in any participant, developed after immunization in 41%, with higher prevalence in participants receiving the lower dose of vaccine. Both antibody and skin test responses occurred in 20-25% of vaccine recipients. Virtually all antibody and skin test responses occurred II participants with initial CD4(+) cell counts of >100 cells/mm(3) IFN-gamma had no significant effect on immune response. Immunization was well tolerated. Trends in CD4(+) cell count, clinical events, and laboratory findings correlated with baseline CD4(+) T lymphocyte count stratum and not with immunization regimen. Oppurtunistic conditions occurred at expected rates. Viral load trends (p24 antigen in all participants and viral RNA by reverse transcription-polymerase chain reaction in a subset of 26 participants) did not correlate with immunization regimen. Conclusion: Immunization of patients with advanced HIV infection with rgp160 resulted in new and augmented humoral and DTH responses, without unexpected significant adverse events or evident clinical benefits attributable to immunization.