鱼类致病性迟钝爱德华氏菌中多药抗性质粒pEIB202的消除

[目的]考察迟钝爱德华氏菌（Edwardsiella tarda）EIB202中大质粒pEIB202在其致病过程中的作用,将质粒pEIB202消除,为开发抗迟钝爱德华氏菌病的安全减毒的活疫苗打下良好基础。[方法]采用同源重组技术以sacB为反向筛选标记消除质粒。[结果]对质粒pEIB202进行序列分析,发现该质粒编码多种抗性基因及部分VI型分泌系统（T4SS）组分,暗示该质粒可能与E.tarda的多重耐药性及致病力相关;质粒消除菌株EIB202Δp丧失氯霉素及四环素抗性,在生长、毒力、胞外蛋白分泌等方面与野生株无显著差异。[结论]PEIB202质粒是造成EIB202多重耐药性的主要原因,在其致病过程中可能并不起直接作用。

Elimination of Multidrug Resistant Plasmid pEIB202 in Fish Pathogenic Edwardsiella tarda

[Objective] The aim of the research was to investigate the function of large plasmid pEIB202 in in the pathogenesis of Edwardsiella tarda EIB202 and eliminate the plasmid pEIB202,so as to lay the foundation for developing safe and live attenuated vaccine against E.tarda.[Method] sacB was used as reverse screening marker to eliminate the plasmid by using homologous recombination technique.[Result] The plasmid pEIB202 was sequenced and it was found that the plasmid encoded multiple resistant genes and some components in type IV secretion system(T4SS),which suggested that the plasmid might be related with the multiple drug-resistance and pathogenicity of E.tarda.The plasmid-eliminated strain EIB202Δp lost the resistance to chloramphenicol and tetracycline,but its growth,virulence and secretion of extracellular proteins had no significant difference with wild-type plants.[Conclusion] pEIB202 plasmid was the main reasons that caused the multi-drug resistance of EIB202 and might have indirect effects in the pathogenesis of EIB202.