Surface proteins of Trichomonas vaginalis (T. vaginalis) were analyzed to study the antigenic variation. The surface proteins of protozoa were labelled by N-hydroxysuccinimide-biotin (NHS-biotin), the NHS-biotin-labelled proteins were immunoprecipitated with rabbit antiserum to purify the antigenic fractions and analysed by SDS-PAGE plus electroblotting. The results obtained in this study were as follows; Biotinylated T. vaginalis-proteins obtained from intact cell and cells disrupted prior to labelling were detected by anti-biotin-peroxidase in Western blots. Labelled proteins were immunoprecipitated by T. vaginalis-immunized rabbit serum and the six bands with the molecular weights of 46, 60, 68, 90, 130 and 220 kDa were identified as having antigenicity. T. vaginalis HY-1, HY-15 and ATCC 50148 were immunoprecipitated by immune rabbit serum after biotinylation and there were no difference from antigenic bands among these strains by this technique. In conclusion with the results obtained in the present study, it was assumed that surface proteins of T. vaginalis were labelled by biotinylation and the six labelled bands at 46, 60, 68, 90, 130 and 220 kDa in their molecular weight were identified as having antigenicity by immunoprecipitation (IP) and this biotinylation-IP technique may be used for further study of surface antigen of T. vaginalis.
