Evaluation of Aldrithiol-2-Inactivated Preparations of HIV Type 1 Subtypes A,B,and D as Reagents to Monitor T Cell Responses

The development of HIV vaccines is an urgent priority and there is need to generate reagents representing multiple subtypes that can be used to screen HIV-1-specific responses. We used Aldrithiol-2 (AT-2), a mild oxidizing reagent, to eliminate the infectivity of HIV while maintaining its structure and ability to be processed for presentation to T cells. Inactivated subtype A, B, and D viruses were evaluated for their ability to stimulate T cell responses in PBMC samples from 18 U.S. subjects infected with HIV-1 subtype B and 32 Ugandan subjects infected with subtypes A and D or recombinants AC and AD. Five HIV-1-negative samples were also analyzed. T cell responses to AT-2-inactivated viral isolates were monitored by interferon-gamma (IFN-γ) intracellular cytokine secretion (ICS) analysis; matched microvesicle preparations served as negative controls. Among the 18 subtype B infected subjects, 39% had CD3⁺ CD4 ⁺ IFN-γ responses and 67% had CD3⁺ CD8⁺ IFN-γ responses. Of the 32 Ugandan subjects, 34% demonstrated CD3⁺ CD4⁺ IFN-γ responses and 78% demonstrated CD3⁺ CD8⁺ IFN-γ responses. Both subtype-specific and cross-reactive responses were observed. Responses to the AT-2 viruses tended to be lower in magnitude than those detected by a set of overlapping gag peptides. Robust lymphoproliferative responses to AT-2 viruses were seen in a subset of subjects. In conclusion, AT-2-inactivated HIV-1 virions stimulated both CD4 and CD8 HIV-1-specific responses and may provide an additional reagent for screening HIV-1-specific responses in HIV seropositives and vaccinees.