title: The novel virulence-related gene stp of Streptococcus suis serotype 9 strain contributes to a significant reduction in mouse mortality.
abstract: Streptococcus suis is an important swine pathogen responsible for a diverse range of diseases. S. suis serotype 2 (SS2) and S. suis serotype 9 (SS9) are the prevalent serotypes in diseased Chinese pigs. Little is known about SS9 virulence factors. Two strains, GZ0565 and SH040917, were isolated from a diseased pig and a healthy pig, respectively. Suppression subtractive hybridization (SSH) was used to identify SS9 virulence genes associated with pathogenicity. We identified 30 gene fragments unique to GZ0565, including stp which encodes a serine/threonine protein phosphatase known to affect the virulence and morphology of bacteria. To investigate the role of stp in pathogenesis of SS9, an isogenic stp mutant (Δstp) and a complementation strain (CΔstp) were constructed. The results demonstrated that the stp affected the expression of a few genes involving in adhesion and virulence for bacteria. The Δstp exhibited a significant decrease in HEp-2 cell adherence, compared with the wild type, and a reduced survival ratio in whole blood. The Δstp was attenuated in a CD1 murine model of infection and its LD50 values was seven-fold higher than the wild type. Our data suggest that stp is involved in the pathogenesis of SS9.
authors.affiliation: Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Haodan
authors.initials: H
authors.lastname: Zhu
authors.forename: Dongyan
authors.initials: D
authors.lastname: Huang
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Zongfu
authors.initials: Z
authors.lastname: Wu
authors.forename: Yan
authors.initials: Y
authors.lastname: Lu
authors.forename: Hongying
authors.initials: H
authors.lastname: Jia
authors.forename: Ming
authors.initials: M
authors.lastname: Wang
authors.forename: Chengping
authors.initials: C
authors.lastname: Lu
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001770:Blood Bactericidal Activity; D002460:Cell Line; D002681:China; D004195:Disease Models, Animal; D005260:Female; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D022781:Hepatocytes / Q000382:microbiology; D006801:Humans; D007928:Lethal Dose 50; D051379:Mice; D050296:Microbial Viability; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013290:Streptococcal Infections / Q000401:mortality / Q000662:veterinary*; D017011:Streptococcus suis / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D016019:Survival Analysis; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology; D014774:Virulence; D037521:Virulence Factors / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D037521:Virulence Factors; D010749:Phosphoprotein Phosphatases