A single regulatory gene is sufficient to alter Vibrio aestuarianus pathogenicity in oysters.
Oyster diseases caused by pathogenic vibrios pose a major challenge to the sustainability of oyster farming. In France, since 2012 a disease affecting specifically adult oysters has been associated with the presence of Vibrio aestuarianus. Here, by combining genome comparison, phylogenetic analyses and high-throughput infections of strains isolated before or during the recent outbreaks, we show that virulent strains cluster into two V. aestuarianus lineages independently of the sampling dates. The bacterial lethal dose was not different between strains isolated before or after 2012. Hence, the emergence of a new highly virulent clonal strain is unlikely. Each lineage comprises nearly identical strains, the majority of them being virulent, suggesting that within these phylogenetically coherent virulent lineages a few strains have lost their pathogenicity. Comparative genomics allowed the identification of a single frameshift in a non-virulent strain. This mutation affects the varS gene that codes for a signal transduction histidine-protein kinase. Genetic analyses confirmed that varS is necessary for infection of oysters and for a secreted metalloprotease expression. For the first time in a Vibrio species, we show here that VarS is a key factor of pathogenicity.
Ifremer, Unité Physiologie Fonctionnelle des Organismes Marins, ZI de la Pointe du Diable, CS 10070, F-29280, Plouzané, France.|UPMC Univ Paris, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Sorbonne Universités, Roscoff, F-29688, France.|Integrative Biology of Marine Models, UMR 8227, CNRS, Roscoff, F-29688, France.
David
D
Goudenège
Laboratoire de Génétique et Pathologie des Mollusques Marins Avenue de Mus de Loup, Ifremer, La Tremblade, F-17390, France.
Marie Agnès
MA
Travers
Ifremer, Unité Physiologie Fonctionnelle des Organismes Marins, ZI de la Pointe du Diable, CS 10070, F-29280, Plouzané, France.|UPMC Univ Paris, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Sorbonne Universités, Roscoff, F-29688, France.|Integrative Biology of Marine Models, UMR 8227, CNRS, Roscoff, F-29688, France.
Astrid
A
Lemire
Ifremer, Unité Physiologie Fonctionnelle des Organismes Marins, ZI de la Pointe du Diable, CS 10070, F-29280, Plouzané, France.
Bruno
B
Petton
Laboratoire de Génétique et Pathologie des Mollusques Marins Avenue de Mus de Loup, Ifremer, La Tremblade, F-17390, France.
Philippe
P
Haffner
Ifremer, Unité Physiologie Fonctionnelle des Organismes Marins, ZI de la Pointe du Diable, CS 10070, F-29280, Plouzané, France.|UPMC Univ Paris, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Sorbonne Universités, Roscoff, F-29688, France.|Integrative Biology of Marine Models, UMR 8227, CNRS, Roscoff, F-29688, France.
Yannick
Y
Labreuche
Laboratoire de Génétique et Pathologie des Mollusques Marins Avenue de Mus de Loup, Ifremer, La Tremblade, F-17390, France.
Delphine
D
Tourbiez
Direction des Sciences du Vivant (DSV), Institut de Génomique (IG), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Evry, F-91057, France.
Sophie
S
Mangenot
Direction des Sciences du Vivant (DSV), Institut de Génomique (IG), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Evry, F-91057, France.|Laboratoire d'Analyse Bioinformatiques en Génomique et Métabolisme (LABGeM), UMR 8030, CNRS, Evry, F-91057, France.
Alexandra
A
Calteau
Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, Institut Pasteur, Paris, F-75015, France.|UMR 3525, CNRS, Paris, F-75015, France.
Didier
D
Mazel
Ifremer, Unité Physiologie Fonctionnelle des Organismes Marins, ZI de la Pointe du Diable, CS 10070, F-29280, Plouzané, France.
Jean Louis
JL
Nicolas
Institut de Génétique et Microbiologie, UMR 8621, CNRS-Université Paris-Sud, Orsay, F-91405, France.
Annick
A
Jacq
Ifremer, Unité Physiologie Fonctionnelle des Organismes Marins, ZI de la Pointe du Diable, CS 10070, F-29280, Plouzané, France.|UPMC Univ Paris, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Sorbonne Universités, Roscoff, F-29688, France.|Integrative Biology of Marine Models, UMR 8227, CNRS, Roscoff, F-29688, France.
Frédérique
F
Le roux
D000818:Animals; D016368:Frameshift Mutation / Q000235:genetics; D005602:France; D005809:Genes, Regulator / Q000235:genetics; D023281:Genomics; D010125:Ostreidae / Q000382:microbiology*; D010802:Phylogeny; D011494:Protein Kinases / Q000235:genetics*; D014733:Vibrio / Q000235:genetics* / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics
D011494:Protein Kinases