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J Vet Sci 2017; 18(4): 439-447  https://doi.org/10.4142/jvs.2017.18.4.439
A serine/threonine phosphatase 1 of Streptococcus suis type 2 is an important virulence factor
Lihua Fang1,2, Jingjing Zhou1, Pengcheng Fan1, Yunkai Yang1, Hongxia Shen1, Weihuan Fang1,*
1Zhejiang University Institute of Preventive Veterinary Medicine and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou 310058, China
2Center for Synthetic Biology Engineering Research, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
Correspondence to: Weihuan Fang
Tel/Fax: +86-571-88982242; E-mail: whfang@zju.edu.cn
Received: March 25, 2016; Revised: September 30, 2016; Accepted: November 23, 2016; Published online: December 31, 2017.
Streptococcus suis is regarded as one of the major pathogens of pigs, and Streptococcus suis type 2 (SS2) is considered a zoonotic bacterium based on its ability to cause meningitis and streptococcal toxic shock-like syndrome in humans. Many bacterial species contain genes encoding serine/threonine protein phosphatases (STPs) responsible for dephosphorylation of their substrates in a single reaction step. This study investigated the role of stp1 in the pathogenesis of SS2. An isogenic stp1 mutant (Δstp1) was constructed from SS2 strain ZJ081101. The Δstp1 mutant exhibited a significant increase in adhesion to HEp-2 and bEnd.3 cells as well as increased survival in RAW264.7 cells, as compared to the parent strain. Increased survival in macrophage cells might be related to resistance to reactive oxygen species since the Δstp1 mutant was more resistant than its parent strain to paraquat-induced oxidative stress. However, compared to parent strain virulence, deletion of stp1 significantly attenuated virulence of SS2 in mice, as shown by the nearly double lethal dose 50 value and the lower bacterial load in organs and blood in the murine model. We conclude that Stp1 has an essential role in SS2 virulence.
Keywords: Streptococcus suis type 2, serine/threonine protein phosphatase, virulence

© 2017 The Korean Society of Veterinary Science.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.