Expression,purification and protective antigen analysis of cell wall protein MRP of Streptococcus suis type 2

AIM: To amplify the mrp gene of Streptococcus suis type 2 05ZYH33,express it in E.coli BL21 in order to acquire high purity recombinant protein MRP,then evaluate the protective antigen of recombinant protein MRP.METHODS: Using PCR technology to obtain the product of mrp gene of 05ZYH33,and then cloned it into the expression vector pET28a(+).The recombinant protein was purified by affinity chromatography,later immunized New Zealand rabbit to gain anti-serum,then test the anti-serum titer by ELISA.The opsonophagocytic killing test demonstrated the abilities of protective antigen of MRP.RESULTS: The truncated of MRP recombinant protein in E.coli BL21 expressed by inclusion bodies,and purified it in high purity.After immunoprotection,the survival condition of CD-1 was significantly elevated.The survival rate of wild-type strain 05ZYH33 in blood was apparently decreased after anti-serum opsonophagocyticed,but the mutant ΔMRP showed no differences.CONCLUSION: MRP represent an important protective antigen activity.