Given the wide sequence divergence of HIV across the globe, and its frightening ability to mutate within a single human being, a vaccine with a small repertoire of cross-reactive immune responses will have limited utility. Given the critical necessity for an HIV vaccine, this application will develop genetic vaccines that generate cross-reacting immune response by several mechanisms. We will test 1) a multi-gene vaccine; 2) multi-mutant vaccines; and 3) DNA shuffled vaccines. In the multi-gene approach, the host is exposed to a cocktail of the different protein from the pathogen in the hope that conserved epitope(s) will generate protective responses against other HIV variants. For the multi-mutant approach, representatives of one antigen from several viral isolates or clades are used in the vaccine to produce cross-protection. While both multi-gene and multi-mutant approaches have some capacity to generate cross-protective immune responses, neither has a proactive mechanism for anticipating emerging HIV variants. To anticipate these emerging variants better, we will use DNA shuffling to recombine and mutate current HIV clades into a population of novel epitopes with an expanded ability to produce cross-reactive responses. Towards these goals, the following Specific Aims will be tested in HLA-A*0201 transgenic mice:
Specific Aim 1. Multi-gene vaccine. Characterize the diversity of cytotoxic T lymphocyte (CTL) and antibody responses generated by the HIV-1 ELI library.
Specific Aim 2. Multi-mutant vaccines. Characterize the level of cross-clade immune responses generated by gp160 clade representatives.
Specific Aim 3. Immune Competition and Antagonism. Determine the level of possible interference produced by problematic epitopes in these complex vaccines.
Specific Aim 4. DNA-shuffled vaccines. Characterize the cross-clade immune responses generated by gp160 clade representatives mutated by DNA shuffling. Since the vaccines will be tested in HLA-A*0201 transgenic mice, this should allow direct translation of the information acquired in these project to be translated into humans. If these Aims are successful, then these three layers of vaccines can be combined to create a vaccine with an exceptional capacity to cross protect against existing HIV clades and those that will emerge in future years. The vaccines may also have therapeutic potential, in shutting down the avenues of mutational escape for HIV in an infected individual.
