河南省某一淡水养殖环节中非O1/O139群霍乱弧菌毒力基因及分子分型分析

目的 了解河南省淡水养殖环节中非O1/O139群霍乱弧菌毒力基因分布及分子分型情况。方法 对河南省淡水养殖环节中50株非O1/O139群霍乱弧菌和3株病人来源菌株进行全基因测序,利用PubMLST-Vc数据库分析其序列分型(ST),利用最小生成树关系图分析进化关系,通过VFDB数据库获得其毒力基因分布。结果 来源于淡水养殖环节和来源于病人的非O1/O139群霍乱弧菌53株菌株均具有黏附、趋化运动、抗吞噬、毒素及酶类等功能的8类毒力相关因子基因,缺失辅助定植、毒素共调、分泌等功能的毒力相关因子基因和副霍乱肠毒素等4个毒素基因。部分毒力相关因子或部分菌株的毒力相关因子毒力基因不全。与3株来源于病人的菌株相比,二者毒力因子基因携带情况相近,除MSHA Ⅳ型菌毛毒力因子mshA基因、荚膜多糖wbuB基因、wbfY基因、rmlB基因、血红素受体hutA基因及Ⅲ型分泌系统vscC2和vcrD2基因外,部分菌株二者携带相同的毒力因子基因。53株非O1/O139群霍乱弧菌分属19个ST型,ST4和ST5是优势ST型,养殖环节来源的菌株与病人来源的菌株分属不同的ST型。19个ST型等位基因位点变异差异数在1~7个,其中分离自淡水养殖环节的非O1/O139群霍乱弧菌菌株17个ST型等位基因位点变异差异数在1~7个,病人来源的非O1/O139群霍乱弧菌菌株2个ST型与分离自淡水养殖环节的非O1/O139群霍乱弧菌菌株ST1、ST2、ST6和ST10属同一簇,与ST1有6个等位基因位点存在差异。结论 河南省淡水养殖环节非O1/O139群霍乱弧菌菌株MLST分型多样化,携带多种毒力相关因子,不同来源菌株携带的毒力基因相同,虽然分属不同的ST型,但还是存在食品安全风险,提醒有关部门采取措施进行防控。

Analysis of virulence genes and molecular typing of non-O1/O139 Vibrio cholerae in a link freshwater aquaculture in Henan Province

To investigate the distribution and molecular typing of virulence genes of non O1/O139 Vibrio cholerae in freshwater aquaculture in Henan. Fifty non O1/O139 Vibrio cholerae strains and 3 patient strains from freshwater aquaculture in Henan were sequenced, and their sequence typing (ST) was analyzed by PubMLST-Vc database. The evolutionary relationship was analyzed by using the minimum spanning tree diagram, and the distribution of virulence genes was obtained through VFDB database. The 53 strains of non-O1/O139 Vibrio cholerae from freshwater aquaculture and patients all have 8 kinds of virulence related factor genes with functions of adhesion, chemotaxis, anti phagocytosis, toxin and enzyme, and that didn’t carried the virulence related factor genes with functions of auxiliary colonization, toxin co regulation, secretion and the toxin genes of paracholesterone enterotoxin and other four toxin genes. The virulence genes of some virulence related factors or some strains were incomplete. Compared with the three strains from patients, the virulence factor gene carrying of the two strains was similar, except for the mshA gene, the podocyte wbuB gene, the wbfY gene, the rm1B gene, the heme receptor hutA gene and the type Ⅲ secretion system vscC2 and vcrD2 genes, Some strains carried the same virulence gene. The 53 strains of non-O1/O139 Vibrio cholerae belonged to 19 ST types. ST4 and ST5 were the dominant ST types. The strains from breeding and patients belonged to different ST types. The number of allelic locus variation differences of the 19 STs is 1-7. Among them, 17 STs of non-O1/O139 Vibrio cholerae strains from freshwater aquaculture had 1-7 allelic locus variation differences. Two STs of non-O1/O139 Vibrio cholerae strains from patients belonged to the same cluster as those of non-O1/O139 Vibrio cholerae strains from freshwater aquaculture, with 6 allelic locus variation differences from ST1. MLST typing of non-O1/O139 Vibrio cholerae strains in freshwater aquaculture in Henan is diversified, carrying a variety of virulence related factors. Some strains and patients’ strains carry the same virulence genes. Although they belong to different ST types, there are still food safety risks, which reminds the relevant departments to take measures to prevent and control.