New Developments On The Virulence Mechanisms Of Aeromonas Hydrophila

This chapter covers new virulence factors/mechanisms that are associated with infections caused by Aeromonas species. We focused primarily on the type 3 secretion system (T3SS) effector AexU, which has ADP-ribosyltransferase and GTPase-activating protein activities and operates by inhibiting NF-kappa B in the host cells. Emphasis was also placed on the T6SS and its effectors haemolysin coregulated protein (Hcp) and valine-glycine-repeat G (VgrG) family protein members in terms of their roles in the pathogenesis of Aeromonas infections. While Hcp inhibits bacterial phagocytosis, VgrG1 through its carboxyl-terminal vegetative insecticidal protein-2 (VIP-2) domain, leads to ADP ribosylation of host cell actin, thus preventing its polymerization and cytotoxicity in the eukaryotic cells. Finally, the role is discussed of three quorum-sensing systems (AI-1-AI-3) in modulating bacterial virulence through second messenger cyclic-diguanylate monophosphate (c-di-GMP).