SspH2 as anti-inflammatory candidate effector and its contribution in Salmonella Enteritidis virulence

Makarem O E Shappo; Qiuchun Li; Zhijie Lin; Maozhi Hu; Jingwei Ren; Zhengzhong Xu; Zhiming Pan; Xinan Jiao

doi:10.1016/j.micpath.2020.104041

SspH2 as anti-inflammatory candidate effector and its contribution in Salmonella Enteritidis virulence

Microb Pathog. 2020 Feb 4:142:104041. doi: 10.1016/j.micpath.2020.104041. Online ahead of print.

Authors

Makarem O E Shappo¹, Qiuchun Li², Zhijie Lin², Maozhi Hu¹, Jingwei Ren², Zhengzhong Xu², Zhiming Pan², Xinan Jiao³

Affiliations

¹ Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agri-food Safety and Quality, Ministry of Agriculture of China, Yangzhou University, China; Jiangsu Key Lab of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, China.
² Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agri-food Safety and Quality, Ministry of Agriculture of China, Yangzhou University, China; Jiangsu Key Lab of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, Yangzhou University, China.
³ Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agri-food Safety and Quality, Ministry of Agriculture of China, Yangzhou University, China; Jiangsu Key Lab of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, Yangzhou University, China. Electronic address: jiao@yzu.edu.cn.

PMID: 32027972
DOI: 10.1016/j.micpath.2020.104041

Abstract

Salmonella enterica serovar Enteritidis (S. Enteritidis) is a facultative intracellular pathogen deploying the type III secretion system (T3SS) encoded by Salmonella Pathogenicity Island 2 (SPI2) to transfer effector proteins into host cells to modify its functions and accomplish intracellular replication. To study the effect of SspH2 on immune response induced by S. Enteritidis, we generated a deletion mutant of the effector gene sspH2 and a plasmid mediated complementary strain in S. Enteritidis C50336. The results of LD50 showed that SspH2 has no obvious effect on the virulence of S. Enteritidis. However, deletion of sspH2 decreased the invasion and intercellular colonization of the bacteria in Caco2 BBE cells. Using bacteriological counts from tissue homogenates the result of colonization in internal organs showed that in spleen and liver tissues, at 3rd and 4th day p.i. there is a significance decreased number of C50336-ΔsspH2 compared to the C50336-WT and C50336-ΔsspH2-psspH2, respectively. The qRT-PCR analysis results of both in vivo and in vitro experiments clearly showed that the mutant strain C50336ΔsspH2 significantly promoted expression of IL-1β, INF-γ, IL-12, and iNOS cytokines compared to the groups infected with the wild type or complementary strains, while the IL-8 synthesis was decreased in the mutant strain infected group. All of these findings revealed that SspH2 promotes the colonization of S. Enteritidis in host cells, and it is an important anti-inflammatory biased effector in Salmonella.

Keywords: Anti-inflammatory response; Salmonella enterica serovar Enteritidis (S. Enteritidis); SspH2; Virulence.