AUTHOR=Morga Benjamin , Renault Tristan , Faury Nicole , Lerond Sophie , Garcia Céline , Chollet Bruno , Joly Jean-Pierre , Lapègue Sylvie , Harrang Estelle , Arzul Isabelle 

TITLE=Contribution of in Vivo Experimental Challenges to Understanding Flat Oyster Ostrea edulis Resistance to Bonamia ostreae

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=Volume 7 - 2017

YEAR=2017

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2017.00433

DOI=10.3389/fcimb.2017.00433

ISSN=2235-2988

ABSTRACT=Bonamiosis due to the parasite Bonamia ostreae has been associated with massive mortality outbreaks in flat oyster stocks in Europe. As eradication and treatment are not possible, the control of the disease mainly relies on transfer restriction. Moreover, selection has been applied to produce resistant flat oyster families, which present better survival and lower prevalence than non-selected oysters. In order to better understand mechanisms involved in resistance to bonamiosis, cellular and molecular responses of 2 oyster groups (selected oysters and wild-type oysters) were analysed in the context of experimental injection and cohabitation infections. Cellular responses including non-specific esterases detection, ROS production and phagocytosis activity were analysed by flow cytometry. Four genes homologous to genes shown to be involved in immunity were selected (Inhibitor of apotosis OeIAP, Fas ligand OeFas-ligand, Oe-SOD and OeEc-SOD) and monitored by quantitative reverse-transcription PCR (qRT-PCR). Infected oysters showed higher phagocytosis activity than controls, phagocytosis allow parasite degradation, but it also contribute to spreading of B. ostreae infection. Infected selected oyster show a lower phagocytosis activity might be a solution against the parasite infection. The expression of the OeIAP gene and OeFas-ligand gene was significantly increased in selected oysters at 5 days post injection. OeIAP gene expression appeared significantly increased in wild-type oysters at 8 days post injection. Our results suggest that resistance to bonamiosis partly relies on the ability of the oysters to modulate apoptosis.