Attenuation of Streptococcus suis virulence by the alteration of bacterial surface architecture.
NeuB, a sialic acid synthase catalyzes the last committed step of the de novo biosynthetic pathway of sialic acid, a major element of bacterial surface structure. Here we report a functional NeuB homologue of Streptococcus suis, a zoonotic agent, and systematically address its molecular and immunological role in bacterial virulence. Disruption of neuB led to thinner capsules and more susceptibility to pH, and cps2B inactivation resulted in complete absence of capsular polysaccharides. These two mutants both exhibited increased adhesion and invasion to Hep-2 cells and improved sensibility to phagocytosis. Not only do they retain the capability of inducing the release of host pro-inflammatory cytokines, but also result in the faster secretion of IL-8. Easier cleaning up of the mutant strains in whole blood is consistent with virulence attenuation seen with experimental infections of both mice and SPF-piglets. Therefore we concluded that altered architecture of S. suis surface attenuates its virulence.
Department of Epidemiology, Research Institute for Medicine of Nanjing Command, Nanjing 210002 China.
Youjun
Y
Feng
Min
M
Cao
Jie
J
Shi
Huimin
H
Zhang
Dan
D
Hu
Jing
J
Zhu
Xianyun
X
Zhang
Meiling
M
Geng
Feng
F
Zheng
Xiuzhen
X
Pan
Xianfu
X
Li
Fuquan
F
Hu
Jiaqi
J
Tang
Changjun
C
Wang
D000595:Amino Acid Sequence; D000818:Animals; D001422:Bacterial Adhesion / Q000235:genetics; D016667:Bacterial Capsules / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D054884:Host-Pathogen Interactions; D006863:Hydrogen-Ion Concentration; D016209:Interleukin-8 / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D007652:Oxo-Acid-Lyases / Q000172:deficiency / Q000235:genetics*; D010587:Phagocytosis; D012794:Sialic Acids / Q000378:metabolism; D013290:Streptococcal Infections / Q000382:microbiology / Q000662:veterinary*; D017011:Streptococcus suis / Q000235:genetics* / Q000472:pathogenicity*; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*; D014774:Virulence
D001426:Bacterial Proteins; D016209:Interleukin-8; D012794:Sialic Acids; C018730:N-acetylneuraminate synthase; D007652:Oxo-Acid-Lyases