Identification of a cell wall-associated subtilisin-like serine protease involved in the pathogenesis of Streptococcus suis serotype 2.
Streptococcus suis is an important swine and human pathogen, and also an emerging zoonotic agent. A surface-associated subtilisin-like serine protease (SspA) of S. suis was identified by screening a genomic expression library as fragments of this protein reacted most strongly with convalescent-phase pig sera. The sspA gene is present in 29 of 33 S. suis serotypes reference strains and is expressed on the surface of S. suis. Relative real-time quantitative PCR assay demonstrated that sspA mRNA expression in vivo was several thousand fold of that in vitro. A sspA(-) mutant was generated from a S. suis serotype 2 strain SC19 by allelic exchange. The mutant was not different from the wild type strain in subcellular structures and in hemolytic phenotype. However, the virulence of the sspA(-) mutant was markedly lower than the wild type in pigs as demonstrated in experimental infections. These data indicated that the surface-associated protein SspA is a conserved virulence factor of S. suis and is involved in the pathogenesis of S. suis.
Hu
Qiaoyun
Q
College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.
Liu
Peng
P
Yu
Zhengjun
Z
Zhao
Gang
G
Li
Jun
J
Teng
Liu
L
Zhou
Mingguang
M
Bei
Weicheng
W
Chen
Huanchun
H
Jin
Meilin
M
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000201:enzymology*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D005798:Genes, Bacterial; D006801:Humans; D008565:Membrane Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D016254:Mutagenesis, Insertional; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013290:Streptococcal Infections / Q000382:microbiology / Q000662:veterinary*; D017011:Streptococcus suis / Q000201:enzymology* / Q000302:isolation & purification / Q000472:pathogenicity*; D020860:Subtilisin / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D016019:Survival Analysis; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*; D014774:Virulence
D001426:Bacterial Proteins; D008565:Membrane Proteins; D020860:Subtilisin