Fluorescent antisera in the detection of serological varieties of Trichomonas vaginalis.

In spite of extensive research devoted to all aspects of the problem of trichomoniasis (reviewed by the Societe fran9aise de gynecologie, '1957), we still know little about the factors which determine the severity of the infection. The clinical reaction to infection with Trichomonas vaginalis varies from the symptomless carrier state to acute vaginitis, and this variation might, in theory, be due to differences in the host response, in the size of the infecting dose, or in the type of the infecting organism. Of these, the last possibility was one that could be investigated in the laboratory. If serotypes do in fact exist, they may help to explain the apparent variation in the infectivity and virulence of the organism. Moreover, the detection of such serological types would be most useful in studying the epidemiology of the infection. Search for serological variants is handicapped by the lack of a suitable test directly applicable to vaginal discharges. At present, using agglutination methods, all strains must be well established in culture before any test is possible. This is timeconsuming and not all new isolations reach the required level of growth, though recent work shows that successful cultivation, using a modified medium, can now be achieved with a large proportion of strains (Whittington, 1957; Feinberg and Whittington, 1957). Nevertheless, a direct typing method applicable to fixed vaginal smears or to the scanty organisms from an early culture would be invaluable. We felt that the method of Coons (reviewed comprehensively by Coons, 1956), using the specific staining ability of antibody labelled with fluorescein, might be suited to the study of this problem. Such an