Studying On Expression One Section Of Muramidase-released Protein Of Streptococcus Suis Type 2 And Its Biological Activity

Streptococcus suis Serotype 2 (SS₂) is a kind of important cause of many different diseases such as pneumonia,blood poisoning,meningitis and arthritis. It not only impaires pig industry, but also affects human health. The disease had happened at England, Germany, Singapore, Holland, Thailand and other country.In china,it was discovered at Guangdong firstly in 1990, after that,it burst out in 1998 and 2005,caused fairly loss and casualty. At present, it is understanded about the pathogenic mechanism of SS2,but some virulent factors have been discoved,such as CPS,MRP,EF,Sly and so on.It is affirm that MRP is one of the virulent factor which is significant. Investigate indicated that MRP can adhere VEC to make SS2 induce meningitis and conglomerate RBC to make SS2 induce septicaemia.The aim is to search function fragment of MRP to make clear the pathogenic mechanism of SS2 and provid rationale for develing subunit vaccine of SS2.1.Cloning and sequence analysising one gene section of muramidase-released protein.Accoding to the mrp gene in GenBank,the fragment of mrp gene (tmrp) containing function-position were selected by analysis of DNAStar software,then a pair of primers were designed ,the endonuclease of BamHI and EcoR I was added to the end of mrp primers.After amplifying the aim-gene of two strains of SS2 by PCR, cloning and sequence analysising on them ,it was discoved that the homologization of them was 99.8%, it indicated that gene section have nothing to do with the difference of virulence of the two strains.2. Prokaryotic expression fusion protein of GST-TMRP and researching on its immunogenicityThe recombinant plasmids pGEX-3xTmrp was constructed and fusion protein of GST-TMRP was purified by affinity chromatograph with Glutathione Sepharose.The purified fusion protein was sdudied on immunoprotection,and result that 60% immunization BALB/c mouse were protected.3. Purifing TMRP and studing on its adhering activityCut GST tag from fusion protein of GST-TMRP by factor Xa,then purified TMRP by affinity chromatograph with Glutathione Sepharose and Benzamidine Sepharose. Studing on the activity of SS2 adhering epithelial cells mediated by TMRP to study on the adhering activity of TMRP.Experimental result indicated that tmrp is conservatism highly, fusion protein of GST-TMRP has much immunoprotection function, TMRP is one of the function-position which can adhere epithelial cells.