Ancestral gene acquisition as the key to virulence potential in environmental Vibrio populations

Type Article
Date 2018-12
Language English
Author(s) Bruto Maxime1, 2, Labreuche Yannick1, 2, James Adele1, 2, Piel Damien1, 2, Chenivesse Sabine2, Petton Bruno1, 3, Polz Martin F.4, Le Roux Frederique1, 2
Affiliation(s) 1 : IFREMER, Unite Physiol Fonct Organismes Marins, CS 10070, F-29280 Plouzane, France.
2 : UPMC Paris 06, Sorbonne Univ, Integrat Biol Marine Models, Stn Biol Roscoff,CNRS,UMR 8227,CS 90074, F-29688 Roscoff, France.
3 : IFREMER, LEMAR, UMR 6539, 11 Presquile Vivier, F-29840 Argenton En Landunvez, France.
4 : MIT, Parsons Lab Environm Sci & Engn, Cambridge, MA 02139 USA.
Source Isme Journal (1751-7362) (Nature Publishing Group), 2018-12 , Vol. 12 , N. 12 , P. 2954-2966
DOI 10.1038/s41396-018-0245-3
WOS© Times Cited 1
Abstract

Diseases of marine animals caused by bacteria of the genus Vibrio are on the rise worldwide. Understanding the eco-evolutionary dynamics of these infectious agents is important for predicting and managing these diseases. Yet, compared to Vibrio infecting humans, knowledge of their role as animal pathogens is scarce. Here we ask how widespread is virulence among ecologically differentiated Vibrio populations, and what is the nature and frequency of virulence genes within these populations? We use a combination of population genomics and molecular genetics to assay hundreds of Vibrio strains for their virulence in the oyster Crassostrea gigas, a unique animal model that allows high-throughput infection assays. We show that within the diverse Splendidus clade, virulence represents an ancestral trait but has been lost from several populations. Two loci are necessary for virulence, the first being widely distributed across the Splendidus clade and consisting of an exported conserved protein (R5.7). The second is a MARTX toxin cluster, which only occurs within V. splendidus and is for the first time associated with virulence in marine invertebrates. Varying frequencies of both loci among populations indicate different selective pressures and alternative ecological roles, based on which we suggest strategies for epidemiological surveys.

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