Many new vaccine strategies have been designed to induce primarily a cell-mediated immune response to HIV antigens. Studies utilizing such novel approaches as genetic vaccination, with or without Thl-associated cytokine adjuvants, have focused on assessing the nature of antigen-specific immune responses generated, but little information on the breadth and epitope specificity of the particular immune responses generated using these approaches is currently available. The applicants have hypothesized that the mode of antigen delivery to the antigen presenting cells (APCs) and the predominant cytokine milieu present during T-cell priming may greatly impact the diversity of epitopes recognized as well as the magnitude of the resulting T cell responses. Furthermore, the applicants have successfully developed an in vitro vaccine model for HIV-1 using cultured autologous human dendritic cells (DC) as a biologic adjuvant to induce primary HIV-specific T cell responses from HIV-1 seronegative individuals. This system allows for the objective characterization of T cell responses generated under easily manipulable priming conditions. One goal of the application is to apply this DC-based technology in order to evaluate the breadth and epitope specificity of T-cell responses induced in vivo using an HLA transgenic mouse vaccine model. This model will allow for determination of the magnitude and diversity of HLA A2-restricted T-cell responses generated using a range of vaccine strategies. Specifically, the applicants propose to: (1) evaluate HLA A2/Kb transgenic mice vaccinated with bone marrow-derived DC transfected by gene gun ex vivo with HIV-1 env, gag/pol, or nef CDNA for the presence of HLA-A2-restricted, HIV-1 specific T-cell responses; (2) evaluate HLA A2/Kb transgenic mice vaccinated directly with HIV-1 CDNA by transdermal gene gun delivery for the presence of HLA-A2-restricted, HIV-1 specific T-cell responses; (3) determine the epitope specificity, avidity, and relative frequency of the HIV-specific, HLA-A2-restricted T-cell responses generated in HLA A2/Kb transgenic mice following vaccination using the strategies described in (1); and (4) determine the impact of co-transfection of Thl-biasing or APC-potentiating cytokines (IL-12, IFN, or GM-CSF) on the magnitude and

specificity of the HLA-A2-restricted, HIV-specific T-cell responses in HLA-A2/Kb transgenic mice resulting from the vaccine strategies described in (1).

R21AI042704

1997-09-30

2000-09-29