Immune priming and portal of entry effectors improve response to vibrio infection in a resistant population of the European abalone

Type Article
Date 2017-01
Language English
Author(s) Dubief Bruno1, Nunes FlaviaORCID1, 2, Basuyaux Olivier3, Paillard Christine1
Affiliation(s) 1 : UEB, Lab Sci Environm Marin LEMAR, Univ Brest UBO, UMR6539,CNRS,UBO,IRD,Ifremer,Inst Univ Europeen M, Pl Nicolas Copernic, F-29280 Plouzane, France.
2 : Lab Ecol Benth Cotiere LEBCO, IFREMER, Ctr Bretagne, DYNECO, F-29280 Plouzane, France.
3 : Ctr Expt ZAC Blainville, Synergie Mer & Littoral, F-50560 Blainville Sur Mer, France.
Source Fish & Shellfish Immunology (1050-4648) (Academic Press Ltd- Elsevier Science Ltd), 2017-01 , Vol. 60 , P. 255-264
DOI 10.1016/j.fsi.2016.11.017
WOS© Times Cited 15
Keyword(s) Immunity, Hemocyte, Abalone, Disease, Extracellular products, Immune priming, Vibrio harveyi, Flow cytometry, Resistance, Phagocytosis, Bacterial growth, qPCR, Gill
Abstract Since 1997, populations of the European abalone Haliotis tuberculata suffer mass mortalities attributed to the bacterium Vibrio harveyi. These mortalities occur at the spawning season, when the abalone immune system is depressed, and when temperatures exceed 17 °C, leading to favorable conditions for V. harveyi proliferation. In order to identify mechanisms of disease resistance, experimental successive infections were carried out on two geographically distinct populations: one that has suffered recurrent mortalities (Saint-Malo) and one that has not been impacted by the disease (Molène). Furthermore, abalone surviving these two successive bacterial challenges and uninfected abalone were used for several post-infection analyses. The Saint-Malo population was found to be resistant to V. harveyi infection, with a survival rate of 95% compared to 51% for Molène. While in vitro quantification of phagocytosis by flow cytometry showed strong inhibition following the first infection, no inhibition of phagocytosis was observed following the second infection for Saint-Malo, suggesting an immune priming effect. Moreover, assays of phagocytosis of GFP-labelled V. harveyi performed two months post-infection show an inhibition of phagocytosis by extracellular products of V. harveyi for uninfected abalone, while no effect was observed for previously infected abalone from Saint-Malo, suggesting that the effects of immune priming may last upwards of two months. Detection of V. harveyi by qPCR showed that a significantly greater number of abalone from the susceptible population were positive for V. harveyi in the gills, indicating that portal of entry effectors may play a role in resistance to the disease. Collectively, these results suggest a potential synergistic effect of gills and haemolymph in the resistance of H. tuberculata against V. harveyi with an important involvement of the gills, the portal of entry of the bacteria.
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