单核细胞增生李斯特菌弱毒株主要毒力基因表达水平分析

Expression Levels of Major Virulence Genes in a Low-pathogenicity Isolate of Listeria monocytogenes

单核细胞增生李斯特菌是重要的食源性病原菌,可引起人与动物的胃肠炎、脑膜炎、败血症、流产等。其感染过程的每一步均由特定的毒力因子介导。本试验应用荧光定量PCR,比较分析单核细胞增生李斯特菌弱毒株H4(4a型)与强毒株10403S(1/2a型)、681(4b型)主要毒力基因(prfA、plcA、hly、mpl、ac-tA、plcB、inl A、inlB和sigB)的表达水平差异。除应激调控因子σB(sigB)外,H4株主要毒力基因的表达水平均显著高于10403S与681。膜裂解因子的高表达导致H4更易暴露于宿主免疫系统而被清除,从而引起毒力下降。本研究为探明这类菌株的弱毒机制奠定了基础。

Listeria monocytogenes is an important foodborne pathogen with manifestations ranging from gastroenteritis to meningitis,septicemia and abortion.Each step of its infection process is mediated by specific virulence factors.This study was attempted to compare the expression levels of major virulence-associated genes(prfA,plcA,hly,mpl,actA,plcB,inlA,inlB and sigB) in low-pathogenicity isolate H4(4a) with those in pathogenic strains 10403S(1/2a) and 681(4b) using real-time PCR assay.Major virulence-associated genes in H4 were expressed at higher levels than those in strains 10403S and 681,except for alternative sigma factor σB(sigB).Due to over-expression of membrane-damaging factors,the bacteria are more likely to be exposed to the host immune systems and readily eliminated from the body.This study presents some clues of the molecular mechanisms of low-pathogenicity of L.monocytogenes.