我国霍乱弧菌毒力协同调节菌毛基因序列分析

Sequence analysis of toxin-coregulated pilus gene of Vibrio cholerae strains isolated from China

目的对我国霍乱弧菌（VC）毒力协同调节菌毛（tcpA）基因进行序列分析.方法 38株VC的tcpA基因经聚合酶链反应扩增、测序和序列分析.结果 13株O139群VC产毒株和15株EVC产毒株（均为流行株）的tcpA类型与EVC标准株N16961为同一类型,共有4个位点碱基发生变异,分为5个亚型.EVC流行株中2 株非产毒株的tcpA类型,1株同N16961,1株为新类型.6株EVC非流行株均为非产毒株,分为2种新类型.2株非O1非O139群VC均为非产毒株,为2种新类型.4种新类型与国外4种类型基因和氨基酸序列比较,同源性为63.8%～84.6%和60.6%～91.7%,趋异性为17.8%～44.6%和8.8%～45.8%,tcpA基因所在的VPI毒力岛的结构是完整的,但部分基因存在一定变异.结论 O139群VC产毒株可能起源于EVC产毒株,然后再进一步分化;在非产毒VC中发现4种新类型tcpA基因.

Objective To analyze sequences of toxin-coregulated pilus （tcpA） gene of Vibrio cholerae （ VC ） strains isolated from China. Methods tcpA genes of 38 Vibrio cholerae strains were amplified by PCR, and sequenced. Results tcpA genes of 13 toxic strains of O139 serogroup VC and 15 toxic and epidemic strains of EVC were the same as that of EVC standard srtain N16961, and there were 4 mutated bases that divided strains into 5 sub-types. In 2 non-toxic and epidemic strains of EVC, one had the same tcpA gene as N16961, and another had new tcpA gene type. tcpA genes of 6 non-toxic and non- epidemic strains of EVC were divided into 2 new types, tcpA genes of 2 non-toxic and non-O1/non-O139 serogroup VC strains were 2 new types. The identities and divergences of 4 new tcpA gene types and 4 types found by others were 63.8% -84. 6% and 17.8% -44. 6% ,those of 8 TcpA types were 60. 6% -91.7% and 8. 8% -45. 8%. The Vibrio cholerae pathbgenicity islands （VPI） of 4 new tcpA types were complete, but there were variable genes in VPIs. Conclusion Toxic VC O139 serogroup strains could be originated from toxic EVC strains, and differentiated more. Four new tcpA genes were found in non-toxic VC strains.