Geographic variation among isolates of Trichomonas vaginalis: demonstration of antigenic heterogeneity by using monoclonal antibodies and the indirect immunofluorescence technique.

Although Trichomonas vaginalis causes one of the most common sexually transmitted diseases, little is known about the antigenic variation of the parasite or about differences between strains in epidemiology or virulence. Variation among isolates of T. vaginalis was investigated by using a panel of monoclonal antibodies, each reactive with different antigens, to test 88 isolates from diverse geographic areas of North America. All isolates of T. vaginalis reacted with at least one of the nine monoclonal antibodies; the individual antibodies reacted with 22%-76% of the isolates. A pool of two broadly reactive antibodies identified all isolates in the study. Four of the most narrowly reactive, or "specific," antibodies demonstrated differences in the antigenic composition of trichomonads isolated from patients in Seattle, Baltimore, and Brooklyn, New York (P less than .005 by chi 2 test). Application of these and other monoclonal antibody probes may facilitate epidemiological studies and provide rapid, reliable methods for direct diagnosis of trichomonads in clinical specimens.