The Clinical, Experimental Differences Between Sequence Type 1 And Sequence Type 7 Streptococcus Suis

A large outbreak due to S.suis serotype 2 emerged in the summer of 2005 in Sichuan Province,China.In this outbreak,mortality and morbidity due tO STSLS were surprisingly high(62.3%).Much evidence indicated that the virulence of serotype 2 ST7 strains emerged in the summer of 2005 in China increased.The reason needs to be investigated in order to better understanding the pathogenic mechanism of Streptococcus suis sequence type 7 that was isolated from shock patients during the outbreak and high pathogenic ST1 strains were used to compare mutually.The present studies demonstrate that mechanism of inducing cytokines production was different between two type strains. ST7 strain possessed stronger capacity to stimulate T-cell,naive T-cell and PBMC proliferate than ST1 strain did.The T-cell response to two strains was dependent upon the presence of APCs.Histoincompatible APCs were sufficient to provide accessory signals to naive T- cell stimulated by two strains,indicating that both strains possess mitogens. But the mitogenic effect was different between them.We proposed that the difference in mitogenic effect between ST1 stains and ST7 strains contributed to the difference in virulence between them.The mitogenic effect should be emphasized when explained the mechanism of Streptococcus suis.