title: First evidence for a Vibrio strain pathogenic to Mytilus edulis altering hemocyte immune capacities.
abstract: Bacterial isolates were obtained from mortality events affecting Mytilus edulis and reported by professionals in 2010-2013 or from mussel microflora. Experimental infections allowed the selection of two isolates affiliated to Vibrio splendidus/Vibrio hemicentroti type strains: a virulent 10/068 1T1 (76.6% and 90% mortalities in 24 h and 96 h) and an innocuous 12/056 M24T1 (0% and 23.3% in 24 h and 96 h). These two strains were GFP-tagged and validated for their growth characteristics and virulence as genuine models for exposure. Then, host cellular immune responses to the microbial invaders were assessed. In the presence of the virulent strain, hemocyte motility was instantaneously enhanced but markedly slowed down after 2 h exposure. By contrast, hemocyte velocity increased in the presence of the innocuous 12/056 M24T1. At the same time interval, 10/068 1T1 invaded hemocytes and was more rapidly internalized than the innocuous strain. Extracellular products (ECPs) prepared from 10/068 1T1 cultures significantly inhibited phagocytic activity while 12/056 M24T1 ECPs had no effect. Furthermore, the pathogenic strain and its ECPs inhibited oxidative burst unlike 12/056 M24T1 strain/ECPs which enhanced ROS production. Taken together, our results suggest that the mussel pathogen 10/068 1T1 may escape immune response by altering hemocytes functions.
authors.affiliation: Laboratory of Ecotoxicology- Aquatic Environments, UMR-I 02, SEBIO, University of Le Havre, F-76063, Le Havre Cedex, France.
authors.forename: Yosra
authors.initials: Y
authors.lastname: Ben Cheikh
authors.affiliation: Ifremer, SG2M-LGPMM, Laboratoire de Génétique et Pathologie des Mollusques Marins, Avenue de Mus de Loup, 17390, La Tremblade, France.
authors.forename: Marie-Agnès
authors.initials: MA
authors.lastname: Travers
authors.affiliation: Ifremer, SG2M-LGPMM, Laboratoire de Génétique et Pathologie des Mollusques Marins, Avenue de Mus de Loup, 17390, La Tremblade, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Morga
authors.affiliation: Ifremer, SG2M-LGPMM, Laboratoire de Génétique et Pathologie des Mollusques Marins, Avenue de Mus de Loup, 17390, La Tremblade, France.
authors.forename: Yoann
authors.initials: Y
authors.lastname: Godfrin
authors.affiliation: Laboratory of Ecotoxicology- Aquatic Environments, UMR-I 02, SEBIO, University of Reims Champagne Ardenne, Campus Moulin de la House, F-51100, Reims, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Rioult
authors.affiliation: Laboratory of Ecotoxicology- Aquatic Environments, UMR-I 02, SEBIO, University of Le Havre, F-76063, Le Havre Cedex, France. Electronic address: frank.lefoll@univ-lehavre.fr.
authors.forename: Frank
authors.initials: F
authors.lastname: Le Foll
mesh_terms: D000818:Animals; D002465:Cell Movement; D006434:Hemocytes / Q000276:immunology* / Q000382:microbiology; D057131:Immune Evasion; D007111:Immunity, Cellular; D007113:Immunity, Innate; D056747:Immunomodulation; D049880:Mytilus edulis / Q000276:immunology*; D018384:Oxidative Stress; D010587:Phagocytosis; D013045:Species Specificity; D014733:Vibrio / Q000276:immunology* / Q000472:pathogenicity; D014735:Vibrio Infections / Q000276:immunology*; D014774:Virulence
keywords: Bacterial infections; Cell-mediated immune response; Green fluorescent protein; Innate immunity; Molluscs