Abstract: Objective To investigate the distribution of subtypes of T.pallidum (TP) in Hengyang and Jiangmen regions.Methods Eighty-five specimens taken from patients with suspected chancre collected in Hengyang and Jiangmen from February 2002 to January 2004 were screened by a PCR targeted TP polA gene, and then the arp gene and tpr gene were amplified from TP positive specimens.The PCR products of tpr gene were digested by restriction endonuclease MSe I.The sizes of the arp gene and the restriction fragment length polymorphism (RFLP) of the tpr gene were analyzed for subtyping.Results Of 69 TP-positive specimens, 57 could be subtyped, and 10 subtypes were found.Among them, 26 (45.6%) were subtype 14d, and other subtypes included 10d(1), 12a(3), 12g(2), 13d(6), 14a(5 ), 14b(2), 14f(6), 15d(5) and 16d(1).No significant difference of the distribution of TP subtypes between Hengyang and Jiangmen was found.Conclusion Multiple T.pallidum subtypes have been prevalent in Hengyang and Jiangmen, although the predominant subtype is 14d, there is no significant geographic heterogeneity between these two regions.

Key words: Treponema pallidum, Molecular subtype