The objective of this proposal is to elucidate the controls of virulence of Trichomonas vaginalis strains, with emphasis on immunologic factors. T. vaginalis, a common parasite of the human urogenital (rarely of the respiratory) system, has strains differing in the inherent virulence levels. When expressed in the host, strain virulence is reflected in the levels of severity of the urogenital (much less often of the bronchopulmonary) disease. Antigenic composition of Trichomonas vaginalis strains is to be compared with that of strains of Trichomonas tenax, a parasite of the oral cavity of humans, found in many individuals with poor conditions in the oral cavity. On occasion, T. tenax and T. vaginalis have been reported from the respiratory tract of individuals with bronchitis and/or pulmonitis. T. tenax strains isolated from the oral cavity are generally considered commensal, in both healthy and unhealthy individuals; any disease is thought to be caused by agents other than the oral flagellates. The uncommon bronchial and pulmonary trichomoniases have been controversial with regard to pathogenicity of the flagellates, especially in the case of T. tenax; however, in many instances the trichomonads found in the respiratory system have not been identified with confidence. Expression of T. vaginalis inherent virulence potential seems to depend on host factors, most of which are poorly understood. Through studies of the correlates between clinical manifestations, and especially of the pathologic changes in humans, cell cultures, and experimental which can be identified by antigenic analysis of many strains. Better understanding of such factors may lead to plausible hypotheses about the pathogenicity mechanism(s). Identification of genes responsible for virulence determinants should allow testing of these hypotheses and possibly lead to production of a vaccine against T. vaginalis. With regard to T. tenax, comparisons of oral and bronchopulmonary isolates with those of T. vaginalis (from either the urogenital or respiratory system) should prove useful in identification of virulence-related factors in the oral flagellates, if any are present in the former species. Since little is known about urogenital trichomoniasis in men, at this time at least, it seems more fruitful to study isolates from women, in whom T. vaginalis infection is about twice as prevalent as in men. Oral trichomoniasis is equally frequent in both sexes, and the same seems to be true of the respiratory-tract infections. Immunogenic surface glycoproteins that may be virulence determinants have been identified in purified T. vaginalis plasma membranes. All strains to be employed have been established in liquid N2 shortly after isolation in axenic culture. Plasma membrane has been and will continue to be obtained by a modification (for trichomonads) of the colloidal magnetite method. The immunologic and immunochemical techniques used in membrane analysis include SDS-PAGE, one- and two- dimensional, immunoblotting, radioimmunoprecipitation, sugar analysis, and monoclonal antibody probes. Polyclonal antibodies raised in rabbits against gel-purified proteins as well as polymerase chain reaction will be used to isolate cDNA clones coding for factors thought to be involved in virulence determination.
