Our long-term goal is to develop a mucosal vaccine that generates mucosal CEA-specific cytotoxic T-lymphocytes (CTL) to treat mucosal CEA-positive tumors. Papillomaviruses (PV) are groups of DNA viruses that infect mucosa and skin. Virus-like particles (VLP) can be formed by the PV structural protein L1. Further, PV VLP can package unrelated plasmid DNA to form a PV pseudovirion. We have shown that the pseudovirions are able to deliver the plasmid DNA to intestinal mucosal lymphoid tissue. Because the PV pseudovirions are mucosa-tropic and induce a predominant Th1 response, which may help induce CTL responses to proteins encoded by the plasmid DNA, we hypothesize that PV pseudovirions that contain plasmid DNA encoding CEA can be used as a mucosal vaccine to induce mucosal CEA-specific CTL responses. To test our hypothesis, we will first use the pseudovirion PV-beta-gal that contains a plasmid encoding beta-galactosidase (beta-gal) as a model vaccine to determine whether oral immunization with the vaccine induces a mucosal CTL response to the beta-gal (our model antigen) in mice. Oral immunization with proteins may induce a systemic unresponsiveness, which is mediated by Th2 cytokines, e.g. interleukin (IL)-10, as well as transforming growth factor (TGF)beta. We will test whether oral immunization with PV-beta-gal has such an effect. Because IL- 12 directs an immune response to a predominant Th1 (interferon [IFN]gamma and IL-2) cytokine response, we will test whether a pseudovirion containing the IL-12 gene (PV-IL-12) will enhance mucosal CTL responses and abrogate the systemic CTL unresponsiveness if it exists. Finally, we will test whether a PV pseudovirion containing the CEA gene plus PV-IL-12 elicits a mucosal CTL response against CEA and mediates antitumor effects in vivo.