Changes Of Cytokines Expression Progile In Pigs Infected By Streptococcus Suis Type 2 And Biologic Proerty Study Of Secreted Nuclease A

Streptococcus suis(S.suis) is an important pathogen responsible for a wide variety of infections in pigs,such as meningitis,septicemia,arthritis,and pneumonia.S.suis 2 can also cause serious enzootic infections in humans,which are associated with septicemia, meningitis,and endocarditis So far,35 different capsular types of S.suis have been described.And S.suis 2 is the most frequently capsular type in diseased pigs all over the world.Over production of several proinflammatory cytokines and chemokines have been considered to be associated with bacteria-induced meningeal inflammation.The up-regulation of proinflammatory mediators in blood by Streptococcus suis 2 may also contribute to the breakdown of the blood-brain barrier.In this study,real-time RT-PCR was performed to quantify the transcripts of various cytokines(IL-1α,IL-1β,TNF-α,IL-8; IL-10,IFN-γ) relevant to proinflammatory cytokines and to analyze the cytokines expression differences in blood of pigs infected by S.suis 2 isolated from strains in Sichuan,China.These results show that,IL-1α,TNF-α,IL-8 and IFN-γvaried more significantly than IL-1βand IL-10.IL-1βalways presented weaker expression compared with others in every time-course.TNF-αbegan to increase at 9 h postinfection with a peak at 42 h postinfection.The change of IL-10 expression was similar to that of TNF-αexcept that it was much slighter.IL-8 mRNA expression had an earlier starting point of increase with a peak at 9 h.With this result,it provided information on variation of cytokines in S.suis infected pig and might help us to explain the characteristic of pathogenesis.At pesent,a number of potential virulence factors have been identified and partially characterized,including Extracellular factor,Murimidase-released protein,Suilysin, Immunoglobulin G-binding Protein,Capsular Polysaccharide,Bacterial Adherence and Now there were some Potential virulence factors has been found they include Secreted Nuclease A,orf 2,38-Kilodalton Inununogenic and so on.SS2 secreted nueleaseA(SsnA) activity detection showed that clinical isolates from surface or internalo locations revealed a significant relationship between expression of nuclease and isolation from an internal site.From this result,we concluded that SsnA was considered as a index which discriminated the infected-serum and immun-serum.The purfied SsnA protein was used to antigen for establishing the method of detecting the antibodies of SsnA.384 immun-serum which showed positive had been detected,and the positive rate was 22.9%.37 infect-serum also had been dectected,and the positive was 81.1%.This result indicated that the purfied SsnA protein was used to discriminate the infected-serum and immun-serum.