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12 results on '"Chang, Peixi"'

11. A Streptococcus suis Live Vaccine Suppresses Streptococcal Toxic Shock-Like Syndrome and Provides Sequence Type-Independent Protection.

Author

Li, Zhiwei, Chang, Peixi, Xu, Jiali, Tan, Chen, Wang, Xiaohong, Bei, Weicheng, and Li, Jinquan

Subjects
*STREPTOCOCCUS, *PATHOGENIC microorganisms, *VACCINES, *POLYSACCHARIDES, *IMMUNIZATION
Abstract

Background: Streptococcus suis is an encapsulated zoonotic pathogen. Increasing antimicrobial resistance invokes the need for effective vaccines. Despite many attempts to develop an effective vaccine, none is currently available.Methods: A capsular polysaccharide (CPS)-expressing attenuated mutant 2015033 was constructed by deleting 5 virulence-associated factors (sly, scpA, ssnA, fhb, and ssads) in an infective S. suis strain SC19. The safety and immune effect of 2015033 were determined both in vitro and in vivo.Results: Deletion of 5 genes did not impact the growth ability and CPS generation of 2015033, and the mutant exhibited no cytotoxicity in different cell models. 2015033 was more easily eliminated by innate immunity both in vitro and in vivo. In addition, 2015033 showed a diminished invasive ability in different mouse organs (brain, lung, and liver) and avirulent properties in mice associated with weak inflammation-inducing ability. Immunization with 2015033 triggered T cell-dependent immunity, suppressed streptococcal toxic shock-like syndrome, and conferred sequence type-independent protection to mice during infection.Conclusions: This study presents the feasibility of the strategy of multigene deletion for the development of promising live vaccines against invasive encapsulated pathogens. [ABSTRACT FROM AUTHOR]

Published
2019
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12. The VraSR regulatory system contributes to virulence in Streptococcus suisvia resistance to innate immune defenses

Author

Chang, Peixi, Li, Weitian, Shi, Guolin, Li, Huan, Yang, Xiaoqing, Xia, Zechen, Ren, Yuan, Li, Zhiwei, Chen, Huanchun, and Bei, Weicheng

Abstract

ABSTRACTStreptococcus suisis a highly invasive pathogen that can cause sepsis and meningitis in pigs and humans. However, we have limited understanding of the mechanisms S. suisuses to evade innate immunity. To investigate the involvement of the two-component signal transduction system of S. suisin host immune defense, we examined the expression of 15 response regulators of S. suisfollowing stimulation with polymorphonuclear leukocytes (PMNs). We found that several response regulators were significantly up-regulated including vraR. Thus, we constructed an isogenic deletion mutant of vraSRgenes in S. suisand demonstrated VraSR promotes both bacterial survival in human blood and resistance to human PMN-mediated killing. The VraSR mutant was more susceptible to phagocytosis by human PMNs and had greater sensitivity to oxidant and lysozyme than wild-type S. suis. Furthermore, in vitrofindings and in vivoevidence from a mouse infection model together strongly demonstrate that ΔvraSRhad greatly attenuated virulence compared with wild-type S. suis. Collectively, our data reveal that VraSR is a critical regulatory system that contributes to the survival of S. suisand its ability to defend against host innate immunity.

Published
2018
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