Antigenicity of Trichomonas vaginalis heat-shock proteins in human infections

Patients infected with Trichomonas vaginalis mount humoral and cellular immune responses that often do not protect against reinfection. The oxidative stressors produced by leukocytes may trigger a heat-shock-like response in T. vaginalis trophozoites, helping the parasite to survive host immune defenses. The antigenicity of T. vaginalis heat-shock proteins (HSPs) was examined by immunoprecipitation of T. vaginalis heat-induced proteins with sera from infected patients and controls. When T. vaginalis was heat-shocked, HSPs of 169-167 and 140-137 kDa were specifically recognized by sera from infected male and female patients. However, the majority of T. vaginalis HSPs were also immunoprecipitated by control sera; all sera recognized 72- to 71-kDa, 47- to 45-kDa, 38- to 37-kDa, 35-kDa, and 31-kDa heat-induced proteins. At least 15 proteins from non-heat-shocked T. vaginalis were immunoprecipitated by sera from infected patients and controls, indicating that natural or cross-reacting antibodies could participate in host responses to trichomoniasis. Molecules of 158, 135, 89, and 74-72 kDa were immunoprecipitated from some non-heat-shocked parasites only by patients' sera. A 38-kDa T. vaginalis protein was immunoprecipitated only by sera from infected females and may be specific for infection in women.