The orphan response regulator CovR: a globally negative modulator of virulence in Streptococcus suis serotype 2.
Streptococcus suis serotype 2 is an emerging zoonotic pathogen responsible for a wide range of life-threatening diseases in pigs and humans. However, the pathogenesis of S. suis serotype 2 infection is not well understood. In this study, we report that an orphan response regulator, CovR, globally regulates gene expression and negatively controls the virulence of S. suis 05ZYH33, a streptococcal toxic shock syndrome (STSS)-causing strain. A covR-defective (DeltacovR) mutant of 05ZYH33 displayed dramatic phenotypic changes, such as formation of longer chains, production of thicker capsules, and increased hemolytic activity. Adherence of the DeltacovR mutant to epithelial cells was greatly increased, and its resistance to phagocytosis and killing by neutrophils and monocytes was also significantly enhanced. More importantly, inactivation of covR increased the lethality of S. suis serotype 2 in experimental infection of piglets, and this phenotype was restored by covR complementation. Colonization experiments also showed that the DeltacovR mutant exhibited an increased ability to colonize susceptible tissues of piglets. The pleiotropic phenotype of the DeltacovR mutant is in full agreement with the large number of genes controlled by CovR as revealed by transcription profile analysis: 2 genes are positively regulated, and 193 are repressed, including many that encode known or putative virulence factors. These findings suggested that CovR is a global repressor in virulence regulation of STSS-causing S. suis serotype 2.
Pan
Xiuzhen
X
Department of Epidemiology, Research Institute for Medicine of Nanjing Command, Nanjing, 210002, China.
Ge
Junchao
J
Li
Ming
M
Wu
Bo
B
Wang
Changjun
C
Wang
Jing
J
Feng
Youjun
Y
Yin
Zhimin
Z
Zheng
Feng
F
Cheng
Gong
G
Sun
Wen
W
Ji
Hongfeng
H
Hu
Dan
D
Shi
Peiju
P
Feng
Xiaodan
X
Hao
Xina
X
Dong
Ruiping
R
Hu
Fuquan
F
Tang
Jiaqi
J
D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000382:microbiology; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D006461:Hemolysis; D006801:Humans; D009000:Monocytes / Q000276:immunology; D009504:Neutrophils / Q000276:immunology; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D013290:Streptococcal Infections / Q000382:microbiology; D017011:Streptococcus suis / Q000472:pathogenicity / Q000502:physiology*; D016019:Survival Analysis; D013552:Swine; D014774:Virulence
D001426:Bacterial Proteins; D012097:Repressor Proteins