Streptococcus suis (S. suis) is an important zoonotic pathogen, which can not only cause severe porcine infectious diseases, including arthritis, meningitis, and pneumonia but also can be transmitted to humans, causing meningitis, permanent hearing loss, septic shock and even death. The two recent large-scale outbreaks of severe S. suis epidemics in China made it well-known to the world. The newly emerging streptococcal toxin shock syndrome (STSS) caused by S. suis has posed serious public health risks. However, the cause of the new emerging STSS of S. suis is still unknown.

In order to uncover the cause of STSS caused by S. suis and track the evolutionary route of S. suis, researchers in the Institute of Microbiology, Chinese Academy of Sciences (IMCAS) initiated comparative genomic analysis of S. suis by Roche Nimblegen tilling microarrays. The results demonstrated that the genome of S. suis is highly variable. The ABC-type transport systems positioned at the recently gained pathogenicity island (PAI) were predicted to greatly contribute to the catastrophic features of STSS. Moreover, many candidate virulence genes were uncovered. Gene gain was found to be the main force of evolution, accompanying with massive genomic rearrangement. A model of the microevolution of S. suis was proposed.This whole-genome comparative analysis provides new insight into the pathogenicity and evolution of SS2 and will contribute to the development of potential therapies and novel preventive measures to the control S. suis infection.

This work was supported by National Program on Key Basic Research Project of China (973 Program), a grant from the Open Fund of State Key Lab of Infections and Diagnostics in Zhejiang University Medical School and a grant of the Innovative Research Group of the National Natural Science Foundation of China. This study was published in BMC Genomics 2011, 12:219 (doi: 10.1186/1471-2164-12-219).

RESEARCHER CONTACT:
Prof. ZHU Baoli, Ph.D.
Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
E-mail: zhubaoli@im.ac.cn