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A single regulatory gene is sufficient to alter V ibrio aestuarianus pathogenicity in oysters
Author(s) -
Goudenège David,
Travers Marie Agnès,
Lemire Astrid,
Petton Bruno,
Haffner Philippe,
Labreuche Yannick,
Tourbiez Delphine,
Mangenot Sophie,
Calteau Alexandra,
Mazel Didier,
Nicolas Jean Louis,
Jacq Annick,
Le roux Frédérique
Publication year - 2015
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12699
Subject(s) - biology , virulence , pathogenicity island , genetics , gene , oyster , genome , microbiology and biotechnology , outbreak , virology , fishery
Summary Oyster diseases caused by pathogenic vibrios pose a major challenge to the sustainability of oyster farming. In F rance, since 2012 a disease affecting specifically adult oysters has been associated with the presence of V ibrio 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 V ibrio species, we show here that VarS is a key factor of pathogenicity.