Stability of the point mutation of the Salmonella Typhimurium rcsC11 attenuated strain

Abstract

The foodborne diseases are usually caused by Escherichia coli, Shigella, Listeria and Salmonella, which is the most prevalent bacterium in Argentina. The Salmonella infection involves many steps where the modulation of genes located in different pathogenesis islands are coordinately controlled. The RcsCDB system of Salmonella controls the colanic acid, flagellar and biofilm synthesis, as well as others virulence processes. Previously, we have studied the rcsC11 mutant harboring a point mutation in the histidine kinase domain of RcsC sensor. This change produces the RcsCDB system constitutive activation, resulting in a mutant with mucoid phenotype and attenuation of virulence. Here, we evaluated the ability the rcsC11 mutant to infect non-phagocytic and phagocytes eukaryotic cells. We also investigated the reversion degree of the rcsC11 mutant to wild-type state by loss the mucoid phenotype, by means of temperature changes, crop aging and chemical mutagenic agent challenges. We found that the rcsC11 mutant produced strong immunogenic response and it was unable to replicate in macrophages. Moreover, no revertant strains were isolated in any of the treatment analyzed, strongly suggesting that the rcsC11 mutation would be fairly stable. The results of this study represent a significant contribution that supports the use of the rcsC11 mutant as candidate for vaccines development.