Identification and characterization of a novel hemolysis-related gene in Streptococcus suis serotype 2.
Streptococcussuis serotype 2 (SS 2) is an important zoonotic pathogen that has caused two major infectious outbreaks of streptococcal toxic shock syndrome (STSS) in China. A novel gene located in the 89K pathogenicity island (PAI) encoding a putative hemolysin-III-related protein (Hhly3) has been previously characterized. In this study, the SS2 deletion mutant of the exogenous gene hhly3 was constructed by homologous recombination. This protein was found to exhibit cytolytic activity, and hemolytic activity of the hhly3 gene knockout mutant (Δhhly3) was significantly lower than that in the wild-type strain ZY05719. In addition, qRT-PCR revealed that Hhly3 played an important role in the expression of the secreted hemolysin SLY, which may be the key reason for the decreased hemolytic activity. Consequently, compared with the WT strain, the infection and pathogenicity of Δhhly3 was also decreased, as evidenced by in vitro bacterial growth in whole blood and by the in vivo zebrafish test, suggesting that hhly3 is a novel exogenous hemolysis-related gene in SS2 strains.
Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China.
Jun-xi
JX
Zheng
Yue
Y
Li
Hui
H
Zhang
Hong-jie
HJ
Fan
Cheng-ping
CP
Lu
D000818:Animals; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D023061:Gene Order; D018390:Gene Targeting; D005798:Genes, Bacterial; D006461:Hemolysis; D006801:Humans; D009154:Mutation; D021381:Protein Transport; D012703:Serotyping; D013290:Streptococcal Infections / Q000382:microbiology; D017011:Streptococcus suis / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D013552:Swine; D037521:Virulence Factors / Q000235:genetics; D015027:Zebrafish
D037521:Virulence Factors