CYTOTOXIC T-CELL RESPONSES TO HPV 16 EARLY GENE PROTEINS

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Human papillomavirus (HPV) type 16 is the most common virus associated with cervical cancer. Little is known of the cell mediated responses to HPV 16 antigens, although preliminary data suggests that tumor protection responses are elicited to E6 and E7 proteins. We have previously mapped T-helper cell epitopes of E7 and now propose to examine the specificity and protective value of cytotoxic T-lymphocyte (CTL) responses to HPV 16 epitopes. Initially, we will investigate CTL responses to E6 and E7 proteins in vitro and in vivo. However, since HPV 16 cannot be propagated in vitro or in laboratory animals it will be necessary to use new approaches. We, therefore, propose to: 1. Study CTL responses first in vitro to E6 and E7 proteins in mice primed with either: a. syngeneic cells transfected with plasmid constructs expressing E6 or E7, or b. vaccinia virus recombinants containing the full length E6 or E7 proteins. This vector allows expression of the whole recombinant protein. 2. Determine whether CTL responses are protective against HPV 16 tumor producing cells and if the same responses will cause regression of existing tumors. 3. Map the epitopes contained within protective proteins using T cell clones. 4. Investigate if these peptides incorporated into the major antigenic site of the Sabin attenuated poliovirus type 1 will stimulate protective CTLs in mice. Since mice are normally non-permissive for poliovirus replication, transgenic mice containing the human poliovirus receptor and allowing viral replication will be used. Spleen cells from immunized transgenics will be tested for specific HPV 16 CTLs in vitro and for tumor protection and regression in reconstituted nude mice. The results will shed light on the usefulness of these vectors as a means of delivering peptides to produce protective mucosal and systemic immunity. Moreover, these chimeras may be the basis for a potential HPV vaccine, with the advantage that epitopes from more than one HPV type could be incorporated.