Gamma irradiated Trichomonas vaginalis was used to initiate a protective immune response in mice by intraperitoneal inoculation using host mortality as the measure of virulence. Irradiated trichomonads of a virulent strain gave some immune protection but no more so than the use of formalin-fixed, virulent trichomonads. A formalin-fixed virulent strain combined with complete Freund's adjuvant (CFA) gave complete protection. Metabolically produced antigens do not appear to be important in conferring protective immunity in these experiments. A common laboratory strain of T. vaginalis (ATCC 30001) was used as an avirulent control. It gave no protection against a virulent strain. Combining CFA with ATCC 30001 (avirulent) gave partial protection indicating that a protective antigen is present, but needed an immune stimulant to be detected. IgG analysis corresponded to the mortality results with the avirulent strain being the weakest responder and the strongest being the formalin-fixed virulent strain with CFA. Western blot analysis indicated a band of about 31-kDa that was present using the protocols that showed from partial to complete protection. This band was not present using the avirulent strain but appeared with the addition of CFA. These results indicated that a 31-kDa protein is present in the avirulent strain but it requires an immune stimulant to be revealed. Whether this antigen confers protective immunity or not in the mouse intraperitoneal model is an open question.
Hostetler, Terryl L.; Daly, James J.; O'Brien, Timothy J.; and Baker, Max L.
"Use of Irradiated and Formalin-fixed Trichomonas vaginalis to Examine Protective Immune Responses in the Mouse Intraperitoneal Model,"
Journal of the Arkansas Academy of Science: Vol. 57
, Article 13.
Available at: http://scholarworks.uark.edu/jaas/vol57/iss1/13