Genetic Background And Relatedness Of Streptococcus Suis Isolated From Different Districts Of China

Four virulence factors (mrp, epf, sly, orf2) from 3 strains of Streptococcus suis serotype 2 isolated from Sichuan were amplified by PCR using specific primers. Nucleotide Sequencing and analysis results revealed that the 4 virulence factors genes (mrp, epf, sly, orf2) existed in the 3 strains of SS2 Sichuan isolates and have high homology of more than 99.5% to the strain 9801 isolated in Jiangsu in 1998 and all other reference isolates, it suggested that the 3 strains of SS2 isolated in Sichuan maybe origined from Jiangsu isolates or have the same origin.Forty-one strains of S. suis serotype 1/2, 2, 7 and 9 isolated from China were identified by multilocus sequence typing (MLST) and virulence-associated gene profiling technique, which allowed the detection of gdh,cps,mrp(mrp~*), epf(epf~*),sly,off2,fops and gapdh. Ten genotypes including 9 virulence-associated genotype and 8 Sequence Types (STs) were founded in 41 strains. 2 newly discovered STs (STN1, STN2) were disvovered.. The genotype ST7 of S. suis serotype 2 is the most prevalent strains, whose virulence-associated genotype is gdh+/cps2+/mrp+/epf+/sly+/orf2+/fbps+/gapdh+. The genotypes isolated from diseased pigs were different from those isolated form healthy pigs. Further more, dendrogram of S. suis isolated in China were constructed by MLST tools.To understand the epidemiology of Streptococcus suis in Chongqingm, one thousands three hundreds and sixty tonsils from healthy pigs in abattoirs of 20 districts and 116 samples from ill pigs were collected for bacterium isolation of Streptococcus suis. And the characterization of isolated bacteria were examined by agglutination test, PCR assays and virulence-associated gene profiling and Multilocus sequence typing (MLST). One hundred and thirty strains of Streptococcus suis were isolated, including 4 trains of SS2, 3 trains of SS7, 2 trains of SS9 and 2 trains of SS1/2. The genotyping of the SS2 strains isolated from Chongqing were notably different from those of strains isolated from clinical ill pigs in Chongqing.