Abstract: 　Objective To detect Trichomonas vaginalis Tv by direct immunofluorescence assay (DFA) and dis- cuss its clinical significance. Methods The parasites at a concentration of 3×10~5 cells/L were fixed by acetone on slides which were then blocked by 1% BSA (bovine serum albumin) or 10% BSA or 10% NCS (newborn calf serum) respective- ly, incubated with different dilution of polyclonal goat anti-Tv IgG (1: 20-1: 2 560) for different incubation time (15, 30, 45, 60, 90, 120 min). 120 clinical vaginal specimens were examined by direct immunofluorescence assay, the wet mount method and the in vitro cultivation. Results Blocked by 1% or 10% BSA, incubated at 37℃ for 45 min with a titer 1: 160 of polyclonal antibody were the optimal conditions for direct immunofluorescence assay. Its sensitivity and specificity were 87. 9% and 98. 6% respectively in comparison with the in vitro cultivation method. Conclusion Direct im- munofluorescence assay is a useful alternative to the wet mount method which shows a lower sensitivity.

Key words: Trichomonas vaginalis, direct immunofluorescence assay, polyclonal antibody