title: MARTX of Vibrio vulnificus biotype 2 is a virulence and survival factor.
abstract: Vibrio vulnificus biotype 2 is a polyphyletic group whose virulence for fish relies on a plasmid. This plasmid contains an rtxA gene duplicated in the small chromosome that encodes a MARTX (Multifunctional, Autoprocessing Repeats-in-Toxin) unique within the species in domain structure (MARTX type III). To discover the role of this toxin in the fitness of this biotype in the fish-farming environment, single- and double-knockout mutants were isolated from a zoonotic strain and analysed in a series of in vivo and in vitro experiments with eel, fish cell lines and amoebae isolated from gills. Mice, murine and human cell lines were also assayed for comparative purposes. The results suggest that MARTX type III is involved in the lysis of a wide range of eukaryotic cells, including the amoebae, erythrocytes, epithelial cells and phagocytes after bacterium-cell contact. In fish, MARTX type III may act as a toxin involved in the onset of septic shock, while in mice it may promote bacterial colonization by preventing phagocytosis of bacterial cells. Moreover, this toxin could protect bacteria from predation by amoebae, which would increase bacterial survival outside the host and would explain the fitness of this biotype in the fish-farming environment.
authors.affiliation: Department of Microbiology and Immunology, College of Medicine, National Cheng-Kung University, Tainan 701, Taiwan.
authors.forename: Chung-Te
authors.initials: CT
authors.lastname: Lee
authors.forename: David
authors.initials: D
authors.lastname: Pajuelo
authors.forename: Amparo
authors.initials: A
authors.lastname: Llorens
authors.forename: Yi-Hsuan
authors.initials: YH
authors.lastname: Chen
authors.forename: José M
authors.initials: JM
authors.lastname: Leiro
authors.forename: Francesc
authors.initials: F
authors.lastname: Padrós
authors.forename: Lien-I
authors.initials: LI
authors.lastname: Hor
authors.forename: Carmen
authors.initials: C
authors.lastname: Amaro
mesh_terms: D000656:Amoeba / Q000382:microbiology; D000818:Animals; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D004524:Eels / Q000382:microbiology; D004847:Epithelial Cells / Q000382:microbiology; D005393:Fish Diseases / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D054884:Host-Pathogen Interactions; D006801:Humans; D051379:Mice; D010586:Phagocytes / Q000382:microbiology; D010587:Phagocytosis; D010957:Plasmids / Q000235:genetics; D014735:Vibrio Infections / Q000382:microbiology / Q000662:veterinary*; D041261:Vibrio vulnificus / Q000235:genetics* / Q000472:pathogenicity*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001427:Bacterial Toxins; C434464:RtxA protein, Vibrio cholerae; D037521:Virulence Factors