RELATIONSHIP OF THE VIRULENCE OF TRICHOMONAS-VAGINALIS AND THE MAJOR HISTOCOMPATIBILITY COMPLEX IN MURINE TRICHOMONAD INFECTION

A biological assay based upon the induction of abscesses in mice injec ted subcutaneously with Trichomonas vaginalis was shown to be a valid method for comparing the virulence of two isolates of T. vaginalis cul tured from two patients, one suffering from severe vaginitis and the o ther exhibiting only mild disease. The data showed excellent correlati on between the physical dimensions of abscesses in mice injected with each trichomonad isolate and the severity of vaginitis produced in the women from whom the isolates were obtained. The assay employed in our study incorporated measurement of the mean abscess volumes from day 1 to day 6 post-inoculation with T. vaginalis. We found that the absces s assay was clearly superior to a murine intraperitoneal assay for vir ulence evaluation of trichomonad isolates. We then used the murine abs cess assay to determine the susceptibility of different strains of mic e to infection with a virulent T. vaginalis isolate so as to test whet her the genetic constitution of the host would influence the pathogene sis of the disease. BALB/c (H-2(d)) mice were susceptible to infection with T. vaginalis, but both CBA/CaH (H-2(k)) and BALB/c-H-2(k) mice w ere shown to be resistant. The quantitation of abscess formation in th ese inbred and congeneic resistant mouse strains demonstrates that the severity of infection with T. vaginalis is governed by genes mapping within the major histocompatibility complex.