title: Outer membrane vesicles are vehicles for the delivery of Vibrio tasmaniensis virulence factors to oyster immune cells.
abstract: Vibrio tasmaniensis LGP32, a facultative intracellular pathogen of oyster haemocytes, was shown here to release outer membrane vesicles (OMVs) both in the extracellular milieu and inside haemocytes. Intracellular release of OMVs occurred inside phagosomes of intact haemocytes having phagocytosed few vibrios as well as in damaged haemocytes containing large vacuoles heavily loaded with LGP32. The OMV proteome of LGP32 was shown to be rich in hydrolases (25%) including potential virulence factors such as proteases, lipases, phospholipases, haemolysins and nucleases. One major caseinase/gelatinase named Vsp for vesicular serine protease was found to be specifically secreted through OMVs in which it is enclosed. Vsp was shown to participate in the virulence phenotype of LGP32 in oyster experimental infections. Finally, OMVs were highly protective against antimicrobial peptides, increasing the minimal inhibitory concentration of polymyxin B by 16-fold. Protection was conferred by OMV titration of polymyxin B but did not depend on the activity of Vsp or another OMV-associated protease. Altogether, our results show that OMVs contribute to the pathogenesis of LGP32, being able to deliver virulence factors to host immune cells and conferring protection against antimicrobial peptides.
authors.affiliation: Ecology of Coastal Marine Systems, CNRS UMR 5119, Montpellier, F-34095, France; Ecology of Coastal Marine Systems, Ifremer, Montpellier, F-34095, France; Ecology of Coastal Marine Systems, University of Montpellier 1, Montpellier, F-34095, France; Ecology of Coastal Marine Systems, University of Montpellier 2 and IRD, Montpellier, F-34095, France.
authors.forename: Audrey Sophie
authors.initials: AS
authors.lastname: Vanhove
authors.forename: Marylise
authors.initials: M
authors.lastname: Duperthuy
authors.forename: Guillaume M
authors.initials: GM
authors.lastname: Charrière
authors.forename: Frédérique
authors.initials: F
authors.lastname: Le Roux
authors.forename: David
authors.initials: D
authors.lastname: Goudenège
authors.forename: Benjamin
authors.initials: B
authors.lastname: Gourbal
authors.forename: Sylvie
authors.initials: S
authors.lastname: Kieffer-Jaquinod
authors.forename: Yohann
authors.initials: Y
authors.lastname: Couté
authors.forename: Sun Nyunt
authors.initials: SN
authors.lastname: Wai
authors.forename: Delphine
authors.initials: D
authors.lastname: Destoumieux-Garzón
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000942:Antigens, Bacterial / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D018093:Gelatinases / Q000096:biosynthesis; D006460:Hemolysin Proteins / Q000096:biosynthesis; D008666:Metalloendopeptidases / Q000096:biosynthesis; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010125:Ostreidae / Q000276:immunology / Q000382:microbiology*; D010588:Phagosomes / Q000382:microbiology; D011112:Polymyxin B / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000096:biosynthesis; D057057:Serine Proteases / Q000096:biosynthesis; D014617:Vacuoles / Q000382:microbiology*; D014733:Vibrio / Q000235:genetics / Q000472:pathogenicity*; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D006460:Hemolysin Proteins; D037521:Virulence Factors; C121437:Vsp protein, bacterial; D057057:Serine Proteases; D012697:Serine Endopeptidases; D018093:Gelatinases; D008666:Metalloendopeptidases; C030895:caseinase; D011112:Polymyxin B