Abstract: Objective To identify new microsatellite loci from genome sequence database for the study of polymorphicsm of Schistosoma japonicum. Methods Schistosoma japonicum isolates were obtained from seven endemic sites in China： Tongling and Guichi counties of Anhui Province， Duchang county of Jiangxi Province， Changde and Yueyang Cities of Hunan Province， Shashi City of Hubei Province， Xichang City of Sichuan Province. In order to study the genetic variance， genomic DNAs of 96 individual adult worms were screened against 17 new Schistosoma japonicum microsatellites and the raw data were analyzed by GenMapper 4.0. Furthermore, the varieties of alleles were inverstigated using GenAlEx 6 and genetic distances within a subpopulation (GenClone) and among populations(UPGMA, MEGA 3.1) were analyzed. Results High levels of polymorphism were found between and within population samples， and significant genetic diversity was observed among the seven subpopulations.Within Jiangxi population, most genetic distances (17 loci) among samples range from 25 to 32, indicating a significant genetic diversity. There are three clusters among the seven populations: Jiangxi, Tonglin, Shashi and Changde population, with the genetics distances ranging from 0.017 8 to 0.036 3; Guichi and Yueyang population belong to another cluster, with the genetic distance of 0.024 7; However, Xichang population is an unique group. Its genetic distances to other populations are notable with a range from 0.019 2 to 0.069 3. Conclusion The 17 new polymorphic microsatellites identified may be used as suitable markers for the study on population genetics of Schistosoma japonicum and the genetic variance of the worms seems to be complicated.

Key words: Schistosoma japonicum, Microsatellite, Polymorphism, China