Typing With Multiple-locus Variable-number Tandem Repeat Analysis For Yersinia Pestis In Yunnan Province And The Epidemiological Significance

Objective To identify genotypes of Yersinia pestis from commensal rodent plaguefoci, wild rodent plague foci, and Yu long plague foci in Yunnan province usingMultiple-Locus Variable-Number Tandem Repeat Analysis(MLVA), and try toclarify the genetic evolutionary relationships of Yersinia pestis from three types ofplague foci and further to understand the intrinsic link of Yersinia pestis in Yunnanprovince and its impact on human so as to provide a basis for establishing areasonable measures of plague control and prevention.Methods The Seven VNTR loci were selected for analying163isolates dispersedacross Yunnan province (including139strains from commensal rodent plague foci,17strains from wild rodent plague foci, and7strains from Yu long plague foci).The loci(M21, M34, YP1335, YPO0320, YPO3743, YPO2984, M29) with strong typingability in Yersinia pestis were selected based on the literature published at nationaland international journals. The QIANEN bacterial DNA extraction kit was used toextract DNA of Yersinia pestis. The concentration of DNA was adjusted to20-100ng/ul. The repeat units was obtained by capillary electrophoresis. Data wereanalyzed by Gene mapper4.0and the final results were saved using Excel. Then datawere analyzed by Bio Numerics software to produce a clustering maps and theminimum spanning tree. Results Among seven VNTR loci, five loci can be used in conducting molecularepidemiological source-tracking in future research and the polymorphism index oftwo loci was less than50%. The results showed that163Yersinia pestis were dividedinto78MLVA genotypes (similarity100%),14clusters (same background),.7groups(similarity>60%). There was a relatively independent genotype among Yersinia pestisfrom three types of plague foci. The MLVAgenotype of seven strains isolated from Yulong plague foci from2006to2008was the same. The Yersinia pestis fromcommensal rodent plague foci after the year1982were a genotype, which includes67MLVA Genotypes and8clusters.Two strains isolated from commensal rodentplague foci in1954and1964were an independent cluster and the same genotype.Seventeen strains from wild rodent plague foci were another different cluster, whichincludes10MLVAgenotypes and5groups.Conclusion MLVA genotypes and ecotypes of Yersinia pestis isolated from Yunnanare quite consistent and MLVA genotypes can provide more information of strains.The genotypes of strains from Yu long plague foci are quite different from that ofstrains from commensal rodent plague foci and wild rodent plague foci in Yunnan. Itis further suggested that Yu long plague foci is a new foci when combining with theinformation of biochemical characteristics. Generally, there is a similar genotype forthe strains isolated from same place in different years, which suggested a certain placeaggregation exists. However, there is dissimilar genotypes for the strains isolated fromdifferent places in same years, which suggested there is no time aggregation forYersinia pestis. The data for MLVAgenotypes of Yersinia pestis in Yunnan establishedmay provide a basis for conducting molecular epidemiological source-tracking.