Development Of Inactivated Vaccine Against Streptococcus Equi Zooepidimicus In Whole Cell Binding M-Like Protein Subunit Vaccines

Streptococcus equi subsp.zooepidemicus(SEZ), a major pathogen causing Swine Streptococcosis, causes meningitis,septicemia,arthritis,endocarditis and sudden death in pigs. The animal disease caused by Streptococcus equi subsp.zooepidemicus is worldwide and is one of the most serious bacterial diseases which hazard pigs in China now. The M-like protein of Streptococcus equi subsp.zooepidemicus is an important surface proteins and virulence factor, having the opsonic function, and can resist the phagocytosis of antibody's phagocytic celles. In this study, the immunogenic M-like protein is expressed in the prokaryotic to create vaccines which can prevent the Swine Streptococcosis caused by Streptococcus equi subsp.zooepidemicus.First of all, the M-like gene was amplified from genomic DNA of Streptococcus equi subsp.zooepidemicus CY strain by polymerase chain reaction(PCR).Then the amplified fragment was cloned in the proper orientation into the site between BamH land Xho I of pGEX-4T-1 via restriction endonuelease BamH land Xho I. The recombinant plasmid was verified by restriction endonuclease analysis to verify the correctness of its reading frame.,and it was transformed into its host E.coli BL21. A recombinant protein of 64000 was expressed after induced by IPTG. The result of Western blotting suggested that fusion proteins could bind with polyclonal antibody against M-like protein which indicated that fusion proteins has an excellent immunogenicity.5 piglets in each group were immunized with inactivated whole cell vaccine of streptococcus equi subspecies which was joined with the different levels' fusion protein. At the same time, the control group piglets were immunized with inactivated whole cell vaccine of streptococcus equi subspecies. Three weeks later, all pigs were infected by lml fresh CY broth (1×105CFU/mL). Results show that the vaccine immune protection system was superior to whole-cell vaccine. Minimum dose of combined vaccine was recombinant protein (0.125 mg)+CY (8×108CFU)...