应用PFGE分析广州稻叶型霍乱弧菌的同源性

Homology analysis of strains of Vibrio cholerae serotype Inaba isolated in Guangzhou by pulsed-field gel electrophoresis analysis (PFGE)

目的分析广州40株稻叶型霍乱弧菌的毒力基因和PFGE特征,探讨菌株的同源性和广州稻叶型霍乱弧菌流行的特点。方法应用PCR方法检测稻叶型菌株的4种毒力基因,采用限制性内切酶NotI对菌株进行PFGE分型,使用BioNumerics Version4.0软件(复选Dice相关系数和UPGMA方法)对菌株进行聚类和同源分析。结果绝大多数水型稻叶霍乱疫情相关菌株为genotypeA型菌,而绝大多数环境分离稻叶型霍乱弧菌为genotypeB型和C型菌。40株霍乱菌株分布于18种pulsotype,水型霍乱疫情相关菌株的pulsotype极为相近(相似性系数98%以上),而环境分离的稻叶型霍乱弧菌呈现明显的pulsotype多样性。结论是否携带ctxA基因是稻叶型霍乱弧菌人源分离株与环境分离株的主要区别之一,绝大多数环境分离的稻叶型霍乱弧菌与人源分离株的同源性较低,但仍需加强对不同来源菌株的同源性分析和溯源追踪。

Objective To analyze the characteristics of pathogenicity-associated genes and PFGE features of 40 strains of Vibrio cholerae（V.cholerae）serotype Inaba isolated in Guangzhou,and study homology and features of cholera epidemic caused by V.cholerae.Methods Polymerase Chain Reaction（PCR）assay was utilized to detect the four pathogenicity-associated genes of these isolates.PFGE using restriction enzyme Not I was employed in the molecular subtyping of V.cholerae isolates and PFGE patterns were analyzed by BioNumerics Version 4.0 software to perform cluster analysis and homology analysis.Pattern profiles were compared by utilizing the Dice coefficient and UPGMA（unweighted pair group method with arithmetic averages）.Results Genotype A strains were found in most of the epidemic involved V.cholerae serotype Inaba.Most of environmentally isolated strains belonged to genotype C and genotype B.Eighteen distinct pulsotypes were distributed among 40 isolates typeable by PFGE.Closely related pulsotypes existed among V.cholerae isolates from cholera epidemic（with similarity value above 98%） and pulsotypes of environmental strains demonstrated obvious diversity.Conclusions One of the major differences of V.cholerae serotype Inaba from cholera epidemic and the environment is whether they carry ctxA gene.Relative low homology was observed among V.cholerae serotype Inaba strains from these two sources,but it is still necessary to enforce the homology analysis and track the source of V.cholerae.