Towards a better overview of virulence and risk management of Vibrio parahaemolyticus, a marine bacterium potentially pathogenic for humans

• Main Author: Sorée, Marion
• Other Authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-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)-Centre National de la Recherche Scientifique (CNRS), Université de Bretagne occidentale - Brest, Dominique Hervio-Heath
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2022
• Subjects: Vibrio parehaemolyticus; Virulence; Genomic; Crassostrea gigas; Accumulation; Depuration; Vibrio parahaemolyticus; Génomique; Dépuration; [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology
• Online Access: https://theses.hal.science/tel-04213596; https://theses.hal.science/tel-04213596/document; https://theses.hal.science/tel-04213596/file/These-2022-SML-Microbiologie-SOREE_Marion.pdf

Vibrio parahaemolyticus {Vp) is a marine bacterium considered as a leading cause of gasiroenteritis associated with raw or undercooked seafood consumption in humans worldwide.Isolatiod of Vp strains lacking known vimlence factors (TDH, TRH, ty pe I II secretion system (TsSS)) in clinical cases highlighted the need to better characterize these facrors and their expressies in in vivo models. Moreover, factorsassociated to the host, the oyster, Crassostrea gigas, should be considered to better accumulation and depuration of Vp from their tissues. The objectives of this thesis were to better characterize the pathogenic potential of environmental strains of Vp and to identify factors associated to oyster which could impact the contamination levels of these bacteria in their tissues.The genomic analysis combined to phenotypic characterization of virulence in the infant rabbit and Galleria mellonella larvae models revealed that, th e TDH does not seem to be the most relevant indicator of Vp pathogenicity, and that larvae mortality was probably explained by Vp’s T3SS -1. These are very interesting new observations which need do be further addressed. Experiments on C.gigas showed that oysters grown in secured structures accumulated experimentally more Vp than oysters grown in intertidal environment and that the ploidy level of oysters (dipioid vs. triploid) did not impact the natural contamination and the experimental accumulation and depuration of Vp.Finally, the use of Lactic acid bacteria which inhibited the growth of Vp in vitro, provided promising results concerningVp elimination during oyster depuration. Vibrio parahaemolyticus (Vp) est une bactérie marine considérée comme la principale cause bactérienne de gastroentérites liées à la consommation de produits de la mer crus ou insuffisamment cuits chez l’Homme dans le monde entier. L’absence de facteurs de virulence connue (TDH, TRH, système de sécrétion de type III (T3SS)) chez des souches Vp isolées de cas cliniques souligne la nécessité de mieux caractériser ...