Study On Secretory Proteins Of Streptococcus Suis Serotype 2 At Different Temperature

Streptococcus suis is an important swine pathogen that causes a number of pathological conditions,such as fever,meningitis,endocarditis,arthritis,pneumonia, septicemia,neurosis symptom and so on.There are currently 35 serotypes of Streptococcus suis,among which serotype 2 is the most popular and pathogenic.At present,there are more study on SS2,but the mechanism on surviving,reproduce and infection in vivo is poorly understand.Thus the topic purpose of our study is exploring some new virulence-related proteins and clarifying pathogenesis by proteomics and real time quantitative PCR.In our study,we established the secretory proteins profile at 37℃of SS2 isolated from Sichuan(named as SC-21) and investigated changes of secretome of SC-21 incubated at 42℃by two-Dimentional Electrophoresis(2-DE) and Image Master^TM 2D Platinum software.As compared secretory proteome at normal temperature with rice plants treated with high temperature(42℃),five differentially expressed proteins which were detected high temperature-up-regulated in 2-D gel and characterized by LC/ESI-MS/MS were DNA nuclease SsnA,protein hydrolase CHAP,ABC-transporter substrate-binding protein-glutamine transport,hypothetical protein SSU05-2101, Unknown protein.To investigate the transcript level of differentially expressed proteins,we detected the relative concentration of SsnA and CHAP genes at different temperature by real-time quantitative PCR.The results as follows:The mRNA expression of two genes at 42℃were up-regulated in vitro.Furthermore,both genes in the brains,lungs,spleens and blood of pigs infected with SC-21 were also up-regulated at transcript level,but the extent of the increasing wasn't identical:SsnA and CHAP were expressed most in brains and lungs respectively.These results indicated that some secretory proteins of SC-21 were expressed differently at the state of diease.Further study of these differential expressed proteins may contribute to understand the pathogenesis of SS2 infection and develop strategies for prevention or therapy.