中文摘要：

RyhB是一种大小为90bp左右的细菌非编码小RNA，已有研究表明存在于鼠伤寒沙门菌和霍乱弧菌中的2种RyhB同源物RyhB-1和IsrE可调控细菌生物膜形成、趋化性和耐酸性。为研究RyhB在肠炎沙门菌致病性上的作用，以及2种同源物能否对毒力调控发挥协同作用，本试验利用λ-Red同源重组系统构建了ryhB-1和isrE单、双缺失株，利用表达载体pBR322和pACYC184分别构建了回补质粒并导入缺失株50336△ryhB-1，50336△isrE，50336△ryhB-1／△isr-E中，获得各突变株相应的回补菌株，检测了野生株和各突变株对1日龄雏鸡半数致死量（LD50）、致死率、体内分布等致病性差异。结果发现，ryhB-1和isrE基因缺失后导致肠炎沙门菌毒力减弱，双基因缺失株毒力下降更为明显，表明2种小RNA均对肠炎沙门菌致病性具有增强作用，且二者对毒力的调控具有协同作用。

英文摘要：

RyhB is a kind of about 90 bp bacterial non-coding small RNA. It was reported that two RyhB homologs RyhB-1 and IsrE,whieb existed in the Salmonella typhirnurium and Vibrio chol- erae could regulate biofilm formation, chemotaxis and acid resistance. To study the pathogenicity and cooperative function of RyhB-1 and IsrE, we constructed ryhB-1 and isrE single and double deletion mutants by the X-Red-based recombination system and corresponding complemented mu- tants by constructing complemented plasmid with pBR322 and pACYC184,and transferring to de- letion mutants 50336△ryhB-1,50336△isrE and 50336△ryhB-1/△isrE. Then we tested the path- ogenic differences of wild type,ryhB-1 and isrE deletion mutants and complemented mutants by inoculating above strains to 1-day-old chickens and detecting LD56, mortality rate and bacterial dis- tribution in chickens. The results showed that the virulence of Salrnonella enteritidis was de- creased in the ryhB-1 or isrE gene deletion strain,especially in ryhB-1 and isrE double deletionstrain. It indicated that ryhB-1 and isrE gene could enhance pathogenicity of Salmonella enteriti dis. The two sRNAs have a cooperative effect in virulence regulation.