Our goal in establishing a National Center for Vaccine Development group is to develop a safe and effective vaccine to prevent AIDS. In order to prevent AIDS, a vaccine should induce protective T and B lymphocyte responses. In particular, HIV specific cytotoxic T lymphocytes (CTL) memory should be induced as well as neutralizing antibodies to HIV. There are three integrated research project teams in this program. Two teams of molecular geneticists, fermentation and protein chemists, will design and construct using recombinant DNA techniques, candidate HIV antigens, expressed by SKB group in E. coli, and the SK-RIT group in yeast, mammalian cells and baculo virus. Candidate antigens will be tested for their interreaction with T cells and B cell products in the third (UMass) laboratory. The ability of HIV constructs to stimulate HIV specific proliferative and CTL responses will be defined using lymphocytes obtained from HIV antibody positive donors, who are not clinically immunocompromised, and immune lymphocytes obtained from mice immunized with vaccinia-HIV recombinant viruses. This approach is based on the recent collaborative experience between the SKB and UMass groups in developing an experimental cross- reactive vaccine against influenza. In those studies and previously unrecognized highly conserved CTL epitope on the hemagglutinin HA2 subunit was identified. Many constructs of influenza virus antigen were screened, and this region of the HA2 was unexpectedly positive in a CTL response assay. Subsequent this epitope has been shown to induce protection against virus strains widely variant in the HA1 subunit. We will be able to screen a large number of overexpressed recombinant DNA prepared HIV viral proteins, fusion proteins, and HIV peptides; and to select for development only those which have the specific ability to induce HIV specific CTL responses and neutralizing antibody responses. We will not pursue many other constructs which do not demonstrate such activities in vitro. These constructs will be valuable for defined HIV antigonic sites active in CTL generation and neutralizing antibody response. This immunological screening can be performed on partially purified protein preparations. We will identify candidate constructs in this way, and then develop improved, highly purified materials for assessing clinical safety, immunogenicity and eventual field efficacy.
