Selection of Vibrio crassostreae relies on a plasmid expressing a type 6 secretion system cytotoxic for host immune cells

• Published in: Environmental Microbiology
• Main Authors: Piel, Damien, Bruto, Maxime, James, Adèle, Labreuche, Yannick, Lambert, Christophe, Janicot, Adrian, Chenivesse, Sabine, Petton, Bruno, Mathias Wegner, K, Stoudmann, Candice, Blokesch, Melanie, Le Roux, Frédérique
• Other Authors: Laboratoire de Biologie Intégrative des Modèles Marins (LBI2M), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO), Alfred Wegener Institute Potsdam, Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Université de Lausanne (UNIL), Ecole Polytechnique Fédérale de Lausanne (EPFL), ANR-16-CE32-0008,REVENGE,L'huître comme niche de l'évolution et l'émergence de vibrios pathogènes(2016)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: SEQUENCE; FAMILY; TREE; ACL; SPLENDIDUS; MORTALITY; PATHOGEN; envir; socio; Pacific; Crassostrea gigas; Pacific oyster
• Online Access: https://doi.org/10.1111/1462-2920.14776; https://hal.sorbonne-universite.fr/hal-02298754/file/Piel%20et%20al.%20-%20Selection%20of%20Vibrio%20crassostreae%20relies%20on%20a%20plasm.pdf; https://hal.sorbonne-universite.fr/hal-02298754

International audience Pacific oyster mortality syndrome affects juveniles of Crassostrea gigas oysters and threatens the sustainability of commercial and natural stocks of this species. Vibrio crassostreae (V. crassostreae) has been repeatedly isolated from diseased animals, and the majority of the strains have been demonstrated to be virulent for oysters. In this study, we showed that oyster farms exhibited a high prevalence of a virulence plasmid carried by V. crassostreae, while oysters, at an adult stage, were reservoirs of this virulent population. The pathogenicity of V. crassostreae depends on a novel transcriptional regulator, which activates the bidirectional promoter of a type 6 secretion system (T6SS) genes cluster. Both the T6SS and a second chromosomal virulence factor, r5.7, are necessary for virulence but act independently to cause haemocyte (oyster immune cell) cytotoxicity. A phylogenetically closely related T6SS was identified in V. aestuarianus and V. tapetis, which infect adult oysters and clams respectively. We propose that haemocyte cytotoxicity is a lethality trait shared by a broad range of mollusc pathogens, and we speculate that T6SS was involved in parallel evolution of pathogen for molluscs.