Putative Inv Is Essential for Basolateral Invasion of Caco-2 Cells and Acts Synergistically with OmpA To AffectIn VitroandIn VivoVirulence of Cronobacter sakazakii ATCC 29544

Abstract

ABSTRACTCronobacter sakazakiiis an opportunistic pathogen that causes neonatal meningitis and necrotizing enterocolitis. Its interaction with intestinal epithelium is important in the pathogenesis of enteric infections. In this study, we investigated the involvement of theinvgene in the virulence ofC. sakazakiiATCC 29544in vitroandin vivo. Sequence analysis ofC. sakazakiiATCC 29544invrevealed that it is different from otherC. sakazakiiisolates. In various cell culture models, an Δinvdeletion mutant showed significantly lowered invasion efficiency, which was restored upon genetic complementation. Studying invasion potentials using tight-junction-disrupted Caco-2 cells suggested that theinvgene product mediates basolateral invasion ofC. sakazakiiATCC 29544. In addition, comparison of invasion potentials of double mutant (ΔompA Δinv) and single mutants (ΔompAand Δinv) provided evidence for an additive effect of the two putative outer membrane proteins. Finally, the importance ofinvand the additive effect of putative Inv and OmpA were also proven in anin vivorat pup model. This report is the first to demonstrate two proteins working synergisticallyin vitro, as well asin vivoinC. sakazakiipathogenesis.