Abstract: 　Objective To study genetic polymorphism of surface adhesion protein 33 (AP33) gene on the seven isolates of Trichomonas vaginalis. Methods PCR technique was performed to amplify AP33 gene from the seven isolates, DNA sequences were obtained from the AP33 gene of the isolates and phylogenetic tree was built. Minimal lethal concentrations(MLC) of metronidazole on the isolates were measured in vitro. Results Percentage of the similarity between 7 isolates and U87098 in GenBank was 98.2%-100%,which indicated a high homology and belonged to isotype isolates. There were four branches between Beijing 1 isolate and Tangshan isolate, Jiujiang 1 isolate and Jiujiang 2 isolate, Beijing 2 isolate and Jiujiang 3 isolate, Chengde isolate and U87098 isolate in phylogenetic tree, which showed a close genetic relationship respectively. No relativity was detected between geographical origin and genetic relationship. Conclusion There is a close genetic relationship among the seven T. vaginalis isolates. MLC showed a difference between isolates which have close relationship.

Key words: Trichomonas vaginalis, Adhesion protein 33, equences analysis, DNA