HIV-specific immunity following immunization with HIV synthetic envelope peptides in asymptomatic HIV-infected patients

Objective: A phase I trial was conducted to evaluate the safety and immunog enicity of an HIV synthetic peptide vaccine in HIV-seropositive individuals . The immunogens used in this study were PCLUS 3-18MN and PCLUS 6.1-18MN en velope peptides. Methods: Eight HIV-infected patients received six subcutaneous injections o f 160 mu g PCLUS 3-18MN in Montanide ISA 51 and were followed longitudinall y for a year after the first immunization. Peripheral blood mononuclear cel ls (PBMC) were tested for peptide-specific T helper and cytotoxic T cell (C TL) responses, HIV-1(MN) neutralizing antibodies and antibodies against HIV PCLUS 3 and P18 MN peptides. Results: PCLUS 3-18MN-specific T helper responses were significantly increa sed at 36 weeks (P < 0.05, after adjustment for multiple comparisons) follo wing initial immunization with PCLUS 3-18MN. A P18MN-specific CTL response, not present prior to vaccination, was observed after immunization in one p atient. Serum HIV-1(MN)-neutralizing antibody titers increased in each of t he three patients who had low titers prior to immunization. Plasma HIV RNA levels and CD4 cell counts did not change appreciably during the study peri od. Conclusions: This trial demonstrates that both peptides can be safely admin istered to HIV-infected individuals and that PCLUS 3-18MN induces increases in HIV peptide-specific immune responses. (C) 1999 Lippincott Williams & W ilkins.