福建省2005-2010年志贺菌分离株的毒力基因分析

Prevalence of virulence genes in isolates of Shigellaspecies from Fujian,2005-2010

目的通过检测福建省志贺菌的毒力基因,了解我省不同志贺菌菌群及血清型的毒力基因分布情况以及流行模式,评估不同菌型的危害性,为菌痢防控工作提供科学的实验依据。方法运用PCR扩增技术,对2005-2010年福建省腹泻病人中分离的104株志贺菌进行ipaH、set1(set1A和set1B)、sen、ial四种毒力基因的检测,分析各毒力基因的阳检率以及毒力基因的分布模式。结果 ipaH、set1(set1A和set1B)、sen、ial毒力基因的阳检率分别为100%、36.54%、66.35%、64.42%,其中set1基因在B群(福氏志贺菌)和D群(宋内志贺菌)的阳检率分别为85%和6.25%;104株志贺分为8种毒力基因分布模式命名为I-VIII,IV型是B群志贺菌的优势基因携带模式(67.5%),VI型是D群志贺菌优势基因携带模式(39.06%),同时D群中I型、VII型和V型基因模式分布也较高。结论 ipaH可作为志贺菌属的鉴定基因,set1毒力基因主要存在于福氏志贺菌(B群)中;B群志贺菌有一个集中优势的基因流行模式IV型,D群有较多的相对优势基因流行模式;说明在志贺菌进化过程中存在复杂分化形式,同时毒力基因的插入和缺失在菌型的变异和分化中有一定的相关性。

Investigation on the prevalence of virulence genes among Shigella spp.will reveal current circulating mode of different groups and serotypes.In this study,virulence genes,i.e.,ipaH,set1（set1A and set1B）,sen and ial,in 104 Shigella isolates from Fujian,2005-2010,were detected by PCR.The positive rates of these genes and their distribution modes were analyzed.It was revealed that positive rates for ipaH,set1,sen,and ial genes were 100%,36.54%,66.35%,and 64.42%,respectively.Notably,the positive rates of set1 were 85% and 6.25% for S.flexneri and S.sonnei,respectively.Based on their virulence gene distribution mode,the 104 Shigella strains were divided into 8 groups.Group IV was the dominant mode（67.5%）for S.flexneri,while Group VI was the dominant mode（39.06%）for S.sonnei.Meanwhile,the distribution modes of Group I,VII and V were relatively common in S.sonnei.These results indicated that ipaH could be used as a target gene for identification of Shigella spp.,and that set1 was the mainly harbored virulence gene in S.flexneri.The observation that Group IV was the unique dominant circulating mode in S.flexneri and there were more relatively clustered modes in S.sonnei,suggested that the evolution process of Shigella spp.involved complicated differentiation,and that insertion and deletion of virulence genes was associated with variation and differentiation of Shigella spp.