Virulence of Enterococcus faecalis dairy strains in an insect model: the role of fsrB and gelE
Virulence of Enterococcus faecalis dairy strains in an insect model: the role of fsrB and gelE
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DOI：
10.1099/mic.0.030775-0
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发表时间：
2009-11-01
期刊：
影响因子：
2.8
通讯作者：
Serror, Pascale
中科院分区：
文献类型：
--
作者：
Gaspar, Frederic;Teixeira, Neuza;Serror, Pascale
尽管肠球菌属中存在多种毒力因子，但肠球菌的毒力仍然是一个有争议的问题。一个主要的考虑因素是在从医院或社区获得性感染以及从食品中分离的菌株中检测相同的毒力基因。本研究的目的是评估两个特征良好的肠球菌毒力因子，FSR和明胶酶，在粪肠球菌食品菌株的潜在毒力的作用。在大蜡螟昆虫模型中比较了不相关的肠球菌分离株（包括携带fsr和gelE操纵子的乳制品菌株）的毒力。粪肠球菌乳制品菌株能够杀死幼虫，并与最广泛用于毒力研究的菌株OG1IRF一样毒力。与此相反，肠球菌durans和屎肠球菌菌株是无毒或弱毒力的G。梅隆内拉为了评估fsrB和gelE在粪肠球菌乳制品菌株毒力中的作用，在两个菌株中独立地缺失这两个基因。Delta fsrB和Delta gelE缺失突变体均产生明胶酶阴性表型。虽然这两个突变都显著减弱了G.在大蜡螟中，Delta fsrB菌株的减毒更强。这些结果与先前的研究结果一致，表明fsrB参与了与毒力相关的其他细胞功能的控制。我们的工作表明，在乳制品肠球菌中存在功能性fSRB和较小程度的gelE，应谨慎考虑。
Despite the existence of various virulence factors in the Enterococcus genus, enterococcal virulence is still a debated issue. A main consideration is the detection of the same virulence genes in strains isolated from nosocomial or community-acquired infections, and from food products. The goal of this study was to evaluate the roles of two well-characterized enterococcal virulence factors, Fsr and gelatinase, in the potential virulence of Enterococcus faecalis food strains. Virulence of unrelated Enterococcus isolates, including dairy strains carrying fsr and gelE operons, was compared in the Galleria mellonella insect model. E faecalis dairy strains were able to kill larvae and were as virulent as strain OG1IRF, one of the most widely used for virulence studies. In contrast, Enterococcus durans and Enterococcus faecium strains were avirulent or poorly virulent for G. mellonella. To evaluate the role of fsrB and gelE in virulence of E faecalis dairy strains, both genes were deleted independently in two strains. The Delta fsrB and Delta gelE deletion mutants both produced a gelatinase-negative phenotype. Although both mutations significantly attenuated virulence in G. mellonella, the Delta fsrB strains were more strongly attenuated. These results agree with previous findings suggesting the involvement of fsrB in the control of other cell functions relevant to virulence. Our work demonstrates that the presence of functional fsrB, and to a lesser extent gelE, in dairy enterococci should be considered with caution.