| Sixteen strains of bacteria were isolated from hearts, livers, spleens, kidneys and bloods of thirty-three pigs with similar symptoms of Swine Streptococcussis and eleven strains were identified as pathogenic Streptococcus suis by morphological observation, hemolysis tests, biochemical tests and challenge tests. In order to establish a highly specific, sensitive and rapid method for detecting Streptococcus suis and typing the bacterial serotypes, Specific primers were designed and synthesized based on serotype 2 ( cps2J ,mrp and ef) gene, serotype 9 (gdh and cps9H) gene, serotype 1 (cps1I) gene and serotype 7 (cps7) gene. A series of PCR methods were established for the detection and the thirty-three strains of bacteria were identified by means of the PCR, it was found that there were eleven strains of the bacteria were positive when detect the gdh gene by using class specific PCR, and eleven gdh positive bacteria were all negative by using serotype 2 multiplex PCR, and three of eleven gdh positive bacteria were positive by using serotype 9 multiplex PCR, also getting the same results by using serotype 9 Taqman FQ-PCR, and three strains of the eleven bacteria were srerotype 9 positive by using sterotype 1,7,9 multiplex PCR, which has the same results with sterotype 9 Taqman FQ-PCR. The target strain of serotype of S. suis could be detected definitely by Taqman FQ-PCR when the template contained as few as 1 copy/μL. The results showed that this method could successfully amplify the recombinant pGEX-T-cps9H plasmids and SS9, while six strains of other bacteria , parasite DNA and SS1, SS2, SS7 which used as a control were all negative, different concentrations of recombinant pGEX-T-cps9H plasmids was amplied 4 times. So Taqman FQ-PCR has a good specificity and repeatability for detecting Streptococcus suis. The PCR assays can be both for diagnostic purposes and in epidemiological and transmission studies of porcine Streptococcus suis. |
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