A glimpse of streptococcal toxic shock syndrome from comparative genomics of S. suis 2 Chinese isolates.
BACKGROUND
Streptococcus suis serotype 2 (SS2) is an important zoonotic pathogen, causing more than 200 cases of severe human infection worldwide, with the hallmarks of meningitis, septicemia, arthritis, etc. Very recently, SS2 has been recognized as an etiological agent for streptococcal toxic shock syndrome (STSS), which was originally associated with Streptococcus pyogenes (GAS) in Streptococci. However, the molecular mechanisms underlying STSS are poorly understood.


RESULTS
To elucidate the genetic determinants of STSS caused by SS2, whole genome sequencing of 3 different Chinese SS2 strains was undertaken. Comparative genomics accompanied by several lines of experiments, including experimental animal infection, PCR assay, and expression analysis, were utilized to further dissect a candidate pathogenicity island (PAI). Here we show, for the first time, a novel molecular insight into Chinese isolates of highly invasive SS2, which caused two large-scale human STSS outbreaks in China. A candidate PAI of approximately 89 kb in length, which is designated 89K and specific for Chinese SS2 virulent isolates, was investigated at the genomic level. It shares the universal properties of PAIs such as distinct GC content, consistent with its pivotal role in STSS and high virulence.


CONCLUSIONS
To our knowledge, this is the first PAI candidate from S. suis worldwide. Our finding thus sheds light on STSS triggered by SS2 at the genomic level, facilitates further understanding of its pathogenesis and points to directions of development on some effective strategies to combat highly pathogenic SS2 infections.
Chen
Chen
C
Beijing Genomics Institute, Chinese Academy of Sciences, Beijing, China.
Tang
Jiaqi
J
Dong
Wei
W
Wang
Changjun
C
Feng
Youjun
Y
Wang
Jing
J
Zheng
Feng
F
Pan
Xiuzhen
X
Liu
Di
D
Li
Ming
M
Song
Yajun
Y
Zhu
Xinxing
X
Sun
Haibo
H
Feng
Tao
T
Guo
Zhaobiao
Z
Ju
Aiping
A
Ge
Junchao
J
Dong
Yaqing
Y
Sun
Wen
W
Jiang
Yongqiang
Y
Wang
Jun
J
Yan
Jinghua
J
Yang
Huanming
H
Wang
Xiaoning
X
Gao
George F
GF
Yang
Ruifu
R
Wang
Jian
J
Yu
Jun
J
D000818:Animals; D002681:China; D004269:DNA, Bacterial / Q000235:genetics; D004195:Disease Models, Animal; D004196:Disease Outbreaks; D016680:Genome, Bacterial; D006801:Humans; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D012772:Shock, Septic / Q000453:epidemiology / Q000382:microbiology*; D013290:Streptococcal Infections / Q000235:genetics / Q000382:microbiology; D017011:Streptococcus suis / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology; D014774:Virulence
D004269:DNA, Bacterial