title: The new insights into the oyster antimicrobial defense: Cellular, molecular and genetic view.
abstract: Oysters are sessile filter feeders that live in close association with abundant and diverse communities of microorganisms that form the oyster microbiota. In such an association, cellular and molecular mechanisms have evolved to maintain oyster homeostasis upon stressful conditions including infection and changing environments. We give here cellular and molecular insights into the Crassostrea gigas antimicrobial defense system with focus on antimicrobial peptides and proteins (AMPs). This review highlights the central role of the hemocytes in the modulation and control of oyster antimicrobial response. As vehicles for AMPs and other antimicrobial effectors, including reactive oxygen species (ROS), and together with epithelia, hemocytes provide the oyster with local defense reactions instead of systemic humoral ones. These reactions are largely based on phagocytosis but also, as recently described, on the extracellular release of antimicrobial histones (ETosis) which is triggered by ROS. Thus, ROS can signal danger and activate cellular responses in the oyster. From the current literature, AMP production/release could serve similar functions. We provide also new lights on the oyster genetic background that underlies a great diversity of AMP sequences but also an extraordinary individual polymorphism of AMP gene expression. We discuss here how this polymorphism could generate new immune functions, new pathogen resistances or support individual adaptation to environmental stresses.
authors.affiliation: Ifremer, UMR 5244, IHPE Interaction Host Pathogen Environment, UPVD, CNRS, Université de Montpellier, CC 80, F-34095 Montpellier, France. Electronic address: ebachere@ifremer.fr.
authors.forename: Evelyne
authors.initials: E
authors.lastname: Bachère
authors.affiliation: Ifremer, UMR 5244, IHPE Interaction Host Pathogen Environment, UPVD, CNRS, Université de Montpellier, CC 80, F-34095 Montpellier, France; Laboratory of Immunology Applied to Aquaculture, Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil.
authors.forename: Rafael Diego
authors.initials: RD
authors.lastname: Rosa
authors.affiliation: Ifremer, UMR 5244, IHPE Interaction Host Pathogen Environment, UPVD, CNRS, Université de Montpellier, CC 80, F-34095 Montpellier, France; Laboratorio de Genética e Inmunología Molecular, Instituto de Biología, Pontificia Universidad, Católica de Valparaíso, Avenida Universidad 330, 2373223 Valparaíso, Chile.
authors.forename: Paulina
authors.initials: P
authors.lastname: Schmitt
authors.affiliation: Ifremer, UMR 5244, IHPE Interaction Host Pathogen Environment, UPVD, CNRS, Université de Montpellier, CC 80, F-34095 Montpellier, France.
authors.forename: Aurore C
authors.initials: AC
authors.lastname: Poirier
authors.affiliation: Ifremer, UMR 5244, IHPE Interaction Host Pathogen Environment, UPVD, CNRS, Université de Montpellier, CC 80, F-34095 Montpellier, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Merou
authors.affiliation: Ifremer, UMR 5244, IHPE Interaction Host Pathogen Environment, UPVD, CNRS, Université de Montpellier, CC 80, F-34095 Montpellier, France.
authors.forename: Guillaume M
authors.initials: GM
authors.lastname: Charrière
authors.affiliation: Ifremer, UMR 5244, IHPE Interaction Host Pathogen Environment, UPVD, CNRS, Université de Montpellier, CC 80, F-34095 Montpellier, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Destoumieux-Garzón
mesh_terms: D000818:Animals; D049896:Crassostrea / Q000235:genetics* / Q000276:immunology*; D006434:Hemocytes / Q000276:immunology* / Q000378:metabolism; D054884:Host-Pathogen Interactions; D007111:Immunity, Cellular
keywords: Antimicrobial peptide; Defensin; Hemocyte; Immunity; Mollusk