Vibrio

Bacteria from the genus Vibrio are dominant species of the marine ecosystems. Some are human human pathogens (for instance V. cholerae) but the vast majority are species responsible for marine animal diseases.

These bacteria can colonize numerous habitats, thrive as free, planktonic living organisms, live in biofilms, or form various associations with their hosts, from symbiosis to commensalism and pathogeny. This adaptability is linked to their capacity to generate genomic diversity (i.e. genomic plasticity), which implies material genetic acquisition through tranformation (by intake of naked DNA), conjugation (a plasmid is transfered from a donor to a recipient cell), or transduction (a bacteriophage injects its DNA into a bacterial cell). In certain cases, exogenous DNA can establich itself as an independent replicon (plasmid, episome), in other cases, it is integrated into the genome of the recipient (genomic island, transposon, integron). Acquisition of new genetic resources can modify the bacterium genotype, confering a selective advantage (antibiotic resistance, virulence).

Vibrio genome comprises two chromosomes. Chromosome I encodes genes involved in essential cell functions, whereas Chromosome II would be important for genomic variability and hence phenotypic variations. Hence, in Vibrio, evolution of virulence is tightly linked to the genome structural feature.

Our project is to identify genetic elements involved in pathogenic Vibrio virulence and to understand their mode of action. Beyond diagnostic applications, this study will give access to evolutive characteristics of Vibrio genomes and help defining the limits of their plasticity.

The strains of interest belong to the species V. aestuarianus, ptahogenic to the oyster Crassostrea gigas, V. tapetis, pathogenic to the clam Ruditapes phillipinarum and V. nigripulchritudo, pathogenic to the shrimp Litopenaeus stylirostris.