Effects of siRNA silencing on the susceptibility of the fish cell line CHSE-214 toYersinia ruckeri

Abstract

AbstractBacterial pathogens are known to co-opt mechanisms of the host cells’ physiology to gain intracellular entrance. Among the facultative intracellular bacteria isYersinia ruckeri, an enterobacterium mostly known as the causative agent of enteric redmouth disease in salmonid fish. In the present study, we applied RNA inhibition to silence twenty pre-selected genes on the genome of a fish cell line (CHSE-214) followed by a gentamycin assay to quantify the effect of this silencing on the susceptibility of the cells to infection. It was found that silencing of 16 out of 20 genes significantly reduced the number ofY. ruckerirecovered at the end of the gentamycin assay. Among the genes with the strongest impact were Rab1A, actin and Rac1, which is consistent with our previous findings that N-acetylcysteine, a chemical inhibitor of Rac1, completely prevented invasion of cells byY. ruckeri. Conversely, silencing of the Rho GTPase activating protein had no statistically significant effect, possibly becauseY. ruckeri, like some other members of theYersiniagenus is able to activate Rho GTPase directly. Similarly, the effect of silencing E-cadherin was not statistically significant, suggesting that this might not be a target for the adhesion molecules ofY. ruckeri. Taken together, these findings improve our understanding of the infection process byY. ruckeriand of the interactions between this bacterial pathogen and host cells.ImportanceIntracellular invasiveness is a mean for bacterial pathogen to gain shelter from the immune system as well as access nutrients. The enterobacteriumY. ruckeriis well characterised as a facultative intracellular pathogen. However, the mechanisms of invasion scrutiny. Investigations have mostly focused on the bacterial virulence rather than on the host’s mechanisms hicjacked during invasion. The present findings therefore allow us to better understand the interaction between this important potentially zoonotic pathogen of fish and host cells in vitro.