Salmonella Enteritidis RfbD interferes with autophagy through REDD1 to promote bacterial survival

Background: Salmonella enterica serovar Enteritidis is an important food-borne intracellular pathogen, which seriously threatens the life and health of humans and other animals. Salmonellosis can lead to the morbidity and death of livestock and poultry, causing serious economic losses. Autophagy can be exploited to eliminate intracellular pathogens. Previously, we reported that dTDP-4-dehydro-β-ւ-rhamnose reductase (RfbD) was able to enhance bacterial colonisation in vivo and in vitro by regulating autophagy. Results: In the present study, we found that RfbD inhibited autophagy by regulating REDD1. Through RNA-sequencing (RNA-seq), we found that REDD1 was affected by RfbD. The results of qRT-PCR and western blotting showed that, the REDD1 RNA and protein levels were notably elevated in the Z11Δ rfbD infection group compared to both the Z11 and Z11Δ rfbD :: rfbD infection groups. REDD1 knockdown decreased the autophagy levels induced by Z11Δ rfbD strongly increased bacterial survival. In contrast, REDD1 overexpression increased the autophagy levels induced by Z11Δ rfbD is higher and bacterial survival was reduced. Conclusions: These findings indicate that REDD1 may be a key factor in the suppression of autophagy by RfbD. Our study provides new insights into the mechanism underlying the interaction between Salmonella enterica and the host.