The CodY regulator is essential for virulence in Streptococcus suis serotype 2

Liping Feng1, 2, Jiawen Zhu1, Haitao Chang1, Xiaoping Gao1, Cheng Gao2, Xiaofeng Wei2,Fangyan Yuan3 & Weicheng Bei1,4

Sci Rep. 2016 Feb 17;6:21241. doi: 10.1038/srep21241.

Speaker: Kuang-Yu Chen (陳冠宇)                             Time: 13:00~14:00, May4, 2016

Commentator: Dr. Jenn-Wei Chen (陳振暐 老師)      Place: Room 601

Abstract:

        Streptococcus suis (S. suis) is an important zoonotic disease. Based on the capsular polysaccharides, 33 types have been identified¹. Among these serotypes, S.suis 2 is thought to be the most virulent and also causes serious infection in humans. S.suis serotype 2 can induce meningitis, septic shock and permanent hearing loss. CodY is a global transcriptional regulator found in many bacteria. CodY is involved in primary metabolism, and virulence regulation in various pathogenic gram-positive bacteria. For example, CodY represses the synthesis of many Staphylococcus aureusvirulence factor, but it can positively affect the expression of numerous virulence factor in Streptococcus pyogenes ². Thus, in terms of virulence, CodY has a variety of roles that might be species-dependent.  To understand the role of CodY in S.suis, the authors construct a codY mutant and compared its phenotype with the WT strain. The author demonstrated that mutation of codY decreased the growth rate, adherence, invasion ability in vitro, capsule thickness, and the surface structures of S. suis 2. The codY mutation also reduced the virulence of S. suis 2 in mice model of infection and enhanced macrophage phagocytosis of S.suis 2. Finally, the codY mutation altered the expression of many virulence related genes, including sialic acid synthesis genes, leading to a decreased sialic acid content in the capsule. In summary, CodY in S.suis 2 can modulate bacterial virulence by affecting growth and colonization of as well as regulating sialic acid synthesis and capsule thickness.

References:

1. Zheng C. et al., Two Spx Regulators Modulate Stress Tolerance and Virulence in Streptococcus suis Serotype 2. PloS one 9, e108197, doi: (2014).10.1371/journal.pone.0108197
2. Malke H., Steiner K., McShan W. M. & Ferretti J. J. Linking the nutritional status of Streptococcus pyogenes to alteration of transcriptional gene expression: the action of CodY and RelA. International journal of medical microbiology : IJMM 296, 259–275, doi: (2006).10.1016/j.ijmm.2005.11.008