Salmonella spv locus suppresses host innate immune responses to bacterial infection.
Salmonella enterica serovar typhimurium (S. typhimurium) is globally distributed and causes massive morbidity and mortality in humans and animals. S. typhimurium carries Salmonella plasmid virulence (spv) locus, which is highly conserved and closely related to bacterial pathogenicity, while its exact role in host immune responses during infection remains to be elucidated. To counteract the invaders, the host has evolved numerous strategies, among which the innate immunity and autophagy act as the first defense. Recently, zebrafish has been universally accepted as a valuable and powerful vertebrate model in analyzing bacteria-host interactions. To investigate whether spv locus enhances the virulence of Salmonella by exerting an effect on the host early defense, zebrafish larvae were employed in this study. LD50of S. typhimurium to zebrafish larvae and bacterial dissemination were analyzed. Sudan black B and neutral red staining were performed to detect the responses of neutrophils and macrophages to Salmonella infection. Autophagy agonist Torin1 and inhibitor Chloroquine were used to interfere in autophagic flux, and the protein level of Lc3 and p62 were measured by western blotting. Results indicated that spv locus could decrease the LD50of S. typhimurium to zebrafish larvae, accelerate the reproduction and dissemination of bacteria by inhibiting the function of neutrophils and macrophages. Moreover, spv locus restrained the formation of autophagosomes in the earlier stage of autophagy. These findings suggested the virulence of spv locus involving in suppressing host innate immune responses for the first time, which shed new light on the role of spv operon in Salmonella pathogenicity.
Medical College of Soochow University, Department of Medical Microbiology, No. 199, Ren Ai Road, Suzhou, Jiangsu, 215123, PR China.
Shu-Yan
SY
Wu
Medical College of Soochow University, Department of Medical Microbiology, No. 199, Ren Ai Road, Suzhou, Jiangsu, 215123, PR China.
Li-Dan
LD
Wang
Medical College of Soochow University, Department of Medical Microbiology, No. 199, Ren Ai Road, Suzhou, Jiangsu, 215123, PR China.
Jin-Ling
JL
Li
Medical College of Soochow University, Department of Medical Microbiology, No. 199, Ren Ai Road, Suzhou, Jiangsu, 215123, PR China.
Guang-Mei
GM
Xu
Medical College of Soochow University, Department of Medical Microbiology, No. 199, Ren Ai Road, Suzhou, Jiangsu, 215123, PR China.
Mei-Ling
ML
He
Medical College of Soochow University, Department of Medical Microbiology, No. 199, Ren Ai Road, Suzhou, Jiangsu, 215123, PR China.
Yuan-Yuan
YY
Li
Medical College of Soochow University, Department of Medical Microbiology, No. 199, Ren Ai Road, Suzhou, Jiangsu, 215123, PR China. Electronic address: hruisdm@163.com.
Rui
R
Huang
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004195:Disease Models, Animal; D006801:Humans; D012480:Salmonella Infections / Q000382:microbiology* / Q000503:physiopathology; D012486:Salmonella typhimurium / Q000235:genetics* / Q000472:pathogenicity*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism; D015027:Zebrafish
D001426:Bacterial Proteins; D037521:Virulence Factors
Autophagosome; Innate immunity; S. typhimurium; Zebrafish; spv locus