IncFⅡs型质粒介导的肠炎沙门氏菌耐药与毒力基因杂合转移的分子特征与风险分析

肠炎沙门氏菌是引发食物中毒的首要致病细菌。项目组前期发现IncFⅡs型质粒是介导肠炎沙门氏菌耐药基因转移的优势质粒，部分耐药模块伴有毒力基因的插入或融合。本项目将以76株携带IncFⅡs型质粒的多重耐药肠炎沙门氏菌为对象，通过测定质粒消除或接合前后菌株的耐药与毒力特征变化，来鉴定由耐药/毒力杂合型质粒介导的高毒耐药菌株；利用单分子测序技术与项目组前期开发的泛耐药基因分析软件PRAP，来解析质粒中耐药与毒力基因的杂合方式及其可移动元件的进化规律，并绘制它们的排布图谱；挑选具有代表性的杂合质粒携带菌株，测定在菌膜状态下，它们在体外鸡肠道模型中的转移频率与侵染特征，来进一步表征杂合质粒的转移风险；综合质粒消除或接合效率、杂合质粒的结构特点及质粒在肠道中的转移风险，从而初步揭示IncFⅡs型质粒介导的肠炎沙门氏菌耐药与毒力基因杂合转移的分子特征，为肠炎沙门氏菌高毒耐药株的防控提供新思路和新靶标。

Salmonella Enteritidis is an important pathogen causing food poisoning. In our previous studies, IncFⅡs type plasmids are the dominant plasmids that mediate the transfer of resistant genes in Salmonella Enteritidis, moreover, some resistant genes are usually accompanied by the insertion or fusion of virulence genes. In this study, we will focus on the molecular characteristics and risk analysis of horizontal transfer of hybrid resistance and virulence genes mediated by these IncFⅡs plasmids in Salmonella Enteritidis. Mutant strains including missing or only carrying of the IncFⅡs plasmid will be obtained by plasmid elimination or co-conjugation. Hypervirulent and resistance strains mediated by hybrid plasmids will be identified by testing the characteristics of resistance and virulence. The arrangement of resistant gens, virulence genes and the evolution of transferable elements in these IncFⅡs plasmids will be uncovered by single-molecule sequencing and the pan-drug resistance gene analysis software developed in our previous studies. Infection characteristics and transfer frequency in the chicken intestinal model of the representative strains will be determined under biofilm conditions, so as to further illustrate the risk of transfer and infection of these hybrid plasmids. The molecular characteristics of horizontal transfer of these hybrid resistance and virulence plasmids will be evaluated by the combined analysis of plasmid elimination or conjugation efficiency, structural features of plasmids, and the risk of plasmids transfer in the chicken intestine. All the results will provide novel ideas and targets for the prevention and control of the multidrug-resistant hypervirulent Salmonella Enteritidis strains.