CHARACTERIZATION OF CYTOTOXIC RESPONSES TO HIV ANTIGENS

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The acquired immunodeficiency syndrome (AIDS) induced by the human immunodeficiency virus (HIV), a pathogenic human retrovirus has reached epidemic proportions worldwide, and the need for immunoprophylaxis to stem the spread of this disease is paramount. Rational design of a vaccine requires a thorough understanding of the immunobiology of HIV infection. While it is not yet known exactly what constitutes protective immunity, or what parameters determine clinical progression of disease, a variety of HIV-specific immune responses have been identified. These include neutralizing antibodies, antibody-dependent cellular cytotoxicity (ADCC), cellular proliferative responses, and cytotoxic T cell (CTL) responses. We propose to systemically investigate the immunogenic epitopes involved in generation of these HIV-specific immune responses, in order that the most important immunogenic epitiopes can be incorporated into a subunit vaccine. Recombinant DNA expression technology will be used by collaborators at the Whitehead Institute to create a library of overlapping clones of HIV proteins in E. coli. E coli lysates or immunoaffinity-column purified fusion protein will then be used as a source of cloned antigen for presentation to HIV- specific CTL. Three different autologous target cell approaches will be used for presentation of antigen. These include a) EBV immortalized B cells b) PHA blasts or c) monocyte/macrophages. The effector CTL to be used will be obtained from HIV seropositive subjects and consist of a) bulk HIV-specific CTL b) peripheral blood mononuclear cells prestimulated with HIV antigens in vitro c) HIV-specific cloned T cells. Immunogenic epitopes will then be used to elute reactive antibodies from serum of HIV seropositive subjects, and these antibodies tested for their ability to mediate ADCC and neutralization. The information provided by these studies will then be used in design of a BCG-HIV recombinant vaccine. Candidate vaccines found promising in animal studies will then be tested in clinical trails in humans.