RTX toxin enhances the survival of Vibrio vulnificus during infection by protecting the organism from phagocytosis.

Vibrio vulnificus is a marine bacterium causing serious septicemia and wound infection in humans. It produces an RTX toxin that can lyse a variety of cells and is important for virulence in mice. In this study, we explored the role of RTX in pathogenesis by characterizing an RTX-deficient mutant.

Regulation of cytotoxicity by quorum-sensing signaling in Vibrio vulnificus is mediated by SmcR, a repressor of hlyU.

Cytotoxicity is an important virulence determinant in the pathogenesis of Vibrio vulnificus, and two cytotoxins, RTX (encoded by rtxA1) and cytolysin/hemolysin (encoded by vvhA), have been identified in this organism. We showed that the quorum-sensing regulator LuxO controlled the cytotoxicity of this organism: a ΔluxO mutant exhibited low cytotoxicity, whereas a constitutively activated luxO mutant, luxO(D47E), remained highly cytotoxic. The cytotoxicity of the ΔluxO mutant was restored when smcR, a Vibrio harveyi luxR homologue repressed by luxO, was further deleted.

Comparative genome analysis of Vibrio vulnificus, a marine pathogen.

The halophile Vibrio vulnificus is an etiologic agent of human mortality from seafood-borne infections. We applied whole-genome sequencing and comparative analysis to investigate the evolution of this pathogen. The genome of biotype 1 strain, V.