Random Amplified Polymorphic DNA Of Swine Streptococcus Suis And Research Of Polyvalent Inactivated Vaccine

Swine streptococcus disease causes huge damage in China as well as in many other countries. It has been reported that this kind of disease can be infected to human beings and some people even died of it. So, finding a simple and fast way to choose certain typical strains by using them producing vaccine is in need.Twelve strains were isolated from disease pigs in Jilin Province for 2002~2003. The pathological, serology cultural characters indicated that the isolated bacteria belonged to genus streptococcus. Most of the strains showed hemolysis a or B on the sheep blood plate, and the result of biochemical experiment was not stable. The isolates could be agglutinated by the Lancefield group A~G latex diagnostic kit. They were identified as group C, D and G. But the rest two strains could not been typed. The pathogenicity to mice of the isolates was different. It demonstrated that group C would not be the only pathogen of swine streptococcus in Jilin Province at present. So it was necessary to produce the polyvalent inactivated vaccine against the swine streptococcus disease.Technique of microbic typing includes traditional method and molecular biology method. Random amplified polymorphic DNA(RAPD)is a new technique based on PCR for DNA polymorphic detecting, and it is extensively applied to gene typing of microbe. This method can amplify genomic DNA segment by random primers, then we analysis its fingerprinting through agarose gel electrophoresis to reveal discrimination among different stains. The results of the present study have shown a relative genetic diversity among the different isolates of streptococcus. In this experiment 7 primers were selected among 20 ones. RAPD is a simple and fast technique, so it has been applied to typing of Streptococcus since it was invented.In this experiment, three families of strains were defined by clustering analysis of RAPD data. The typical isolates were used to make vaccine and experiment showed it worked well.In summary, the results of this study indicate that fingerprinting by RAPD analysis is a useful technique for the choosing typical streptococcus strains.