Safety and immunogenicity of HIV-1 Tat toxoid in immunocompromised HIV-1-infected patients

Objectives: To antagonize the deleterious effects of the HIV-1 toxin extracellular Tat on uninfected immune cells, we developed a new strategy of anti-HFV-1 vaccine using an inactivated but immunogenic Tat (Tat toxoid). Tat toxoid has been assayed for safety and immunogenicity in seropositive patients. Method: The phase I vaccine clinical trial testing Tat toxoid preparation in Seppic Isa 51 oil adjuvant was performed on 14 HIV-1-infected asymptomatic although biologically immunocompromized individuals (500-200 CD4⁺ cells/mm³). Results: Following as many as 8 injections, no clinical defects were observed. All patients exhibited an antibody (Ab) response to Tat, and some had cell-mediated immunity (CMI) as evaluated by skin test in vivo and T-cell proliferation in vitro. Conclusion: These results provide initial evidence of safety and potency of Tat toxoid vaccination in HIV-1-infected individuals.