The focus of this project is the use of recombinant genetic methods to express epitopes of the major outer membrane protein of Chlamydia trachomatis in ways which will facilitate the induction of mucosal immune responses to these epitopes. Two methods are being used. 1) The epitopes are being expressed on surface exposed regions of poliovirus. Attenuated poliovirus strains may serve as safe and effective infectious vaccine vectors for stimulation of mucosal immunity. 2) The epitopes are being genetically fused to the E. coli heat labile toxin (LT). LT has the unusual property of breaking oral antigen tolerance and thus, functions as a potent mucosal adjuvant. The antigenic and immunogenic properties of epitopes expressed in each of these systems are being characterized.