中国土拉弗朗西斯菌数目可变串联重复多态性位点特有重复数的研究

Studies on the unique repeat numbers of the VNTR in Chinese Francisella tularensis

目的采用多位点可变数目串联重复分析(MLVA)方法研究中国土拉弗朗西斯菌(土拉菌)的遗传特征。方法根据以往文献,选取对B型土拉菌分辨力较高的12个数目可变串联重复多态性(VNTR),对10株中国土拉菌和29株已公布测序的参考菌株进行MLVA分型研究。结果 MLVA分析显示,中国菌株在4个VNTR位点具有特有的重复数:Ft-M3重复数是5,Ft-M18重复数是1,Ft-M20重复数是2,Ft-M21重复数是2。12个VNTR位点组合分析,得出重复数比较接近的是:410108和日本FSC022;410112、410113和德国F92;410116、410117和美国OSU18、俄罗斯LVS。结论根据特有的重复数,通过检测Ft-M3、Ft-M18、Ft-M20和Ft-M21位点,可以把中国本土土拉菌和国外土拉菌区分开。另外,相对于欧美国家和日本,中国土拉菌具有更多的遗传多样性。

Objective To explore the genetic feature of Chinese Francisella tularensis using MLVA（multiple- locusvariable number tandem repeat analysis）.Methods Based on previous studies, 12 VNTR（variable number of tandemrepeats） were selected that have higher resolving power on type B, and MLVA typing was conducted on 10 strains ofChinese F. tularensis and 29 reference strains that have been sequenced and published.Results The MLVA analysis indicated that Chinese F. tularensis has the unique copy numbers at the four VNTR： the copy number of repeat motif is 5 at the Ft-M3, and that is 1 at the Ft-M18, 2 at the Ft-M20, and 2 at the Ft-M21. Combined 12 VNTR analysis showed that the copy numbers of repeat motif were similar among some F. tularensis strains as follow：410108 and Japanese FSC022;410112, 410113 and German F92; 410116, 410117 and American OSU18, Russian LVS.ConclusionBy examining the 4VNTR i.e. Ft-M3, Ft-M18, Ft-M20 and Ft-M21, a given isolate can be determined whether it is indigenous to China according to the unique copy numbers of repeat motif. In addition, the Chinese F. tularensis has higher genetic diversity comparing with F. tularensis from Europe, USA and Japan.