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Aquaculture Environment Interactions

    AEI prepress abstract   -  DOI: https://doi.org/10.3354/aei00450

    Increased growth metabolism promotes viral infection in susceptible oyster population

    Bruno Petton, Marianne Alunno-Bruscia, Guillaume Mitta, Fabrice Pernet*

    *Corresponding author:

    ABSTRACT: The magnitude of epidemics depends on host susceptibility to the disease, a trait influenced by the genetic constitution of the host and its environment. While the genetic basis of disease susceptibility is often associated with immune capacities, environmental effects generally reflect complex physiological trade-offs. We suggest here that in the case of obligate pathogens whose proliferation depends on the cellular machinery of the host (e.g. viruses), disease susceptibility is directly influenced by host growth. To test our hypothesis, we focused on a viral disease affecting an ecologically relevant model exploited worldwide, the Pacific oyster Crassostrea gigas. Oysters originating from 3 lines with contrasting resistance to the disease were divided into 3 groups displaying different growth rates and acclimated to 3 food levels and 2 temperatures to generate different growth rates. Then, these oysters were exposed to the virus and we estimated survival and viral shedding. Finally, we developed a risk model to prioritise the relative importance of temperature, food, genetic selection and growth on disease-induced mortality. We found that increasing growth through temperature, food level, or selection of fast-growing animals all increased mortality, especially in host populations where susceptible phenotypes dominate. Food provisioning was the most influential factor and associated with higher viral shedding, followed by temperature, resistance phenotype and growth rate. We suggest that growth-forcing factors may promote the development of obligate intracellular pathogens and epidemic risk, thus opening up perspectives for disease management based on manipulative metabolism.