Meeting Abstract
An important coral pathogen Vibrio coralliilyticus causes infection of fish and shellfish, including Eastern and Pacific oyster larvae. This bacterium was the cause of multiple recent hatchery crashes in Oregon and Washington states, although its impact on adult oyster populations is not yet clear. The extent of the coastal dead zones is increasing with global warming which can increase oysters’ vulnerability to the pathogen. We examined the effects V. coralliilyticus infection on oysters under normoxic and anoxic conditions including host mortality and immune response and expression of genes involved in virulence and intracellular signaling of the pathogen. The combination of V. coralliilyticus and anoxia resulted in 100% mortality after 6 days of exposure, where 100% of oysters survived 18 days of exposure to anoxia or bacterial stress alone. Concomitant anoxia and pathogen stress resulted in a significant increase in the hypoxia inducible factor, lectin, and key antioxidant enzymes in oyster immune cells. Anoxia exposure led to a significant increase of the expression of a zinc-metalloprotease (vcpA) in V. coralliilyticus. Expression of other putative virulence factors (hemolysin and flagellum) was higher in normoxia. This indicates that different virulence factors are activated in normoxia and anoxia possibly contributing to differential mortality of the hosts. Our findings show the importance of V. coralliilyticus as a potential pathogen for adult oysters and the potentially virulence-enhancing effects of anoxia via increased intracellular signaling enhancing hosts’ morbidity and mortality.
