Research Area 3: Oysters act as vectors for disease pathogens

The oyster lives in coastal waters that have highly variable water quality (e.g., low dissolved oxygen, high pH) and substantial pollutant loadings (e.g., metal and organic pollutants). Like other filter-feeding bivalves, oysters harbor and concentrate pathogens that occur in their marine habitat and transfer them to humans when the oysters are eaten. Postdoctoral fellow Brett Macey develop an in vivo assay that quantifies the persistence and degradation of live bacterial pathogens in the eastern oyster, Crassostrea virginica, as well as externalization of live bacteria from the oyster to the environment. He found that water quality factors such as pH and O2 levels and seasonal variation can impact the ability of oysters to inactivate bacterial pathogens, in this case Vibrio campbellii, within the tissues of the animal (Macey et al., 2008). He also led a team of researchers at the Hollings Marine lab to reveal the impact of metal contaminants on the physiological status of oysters (Macey et al., in preparation). Graduate student Heidi Williams employed a similar assay to evaluate what tissues of the oyster are involved in the inactivation and elimination of internalized bacteria. Surprisingly, while major organs such as the mantle and hepatopancreas play an important role in these processes, gonadal tissues displayed the greatest antibacterial activity in the oyster (Williams et al., 2008). Gonadal tissues develop and are resorbed seasonally, suggesting that disease resistance might be predicted to fluctuate with factors that influence gonadal development. All three of these studies lead to new and exciting questions, as we attempt to model the complex interaction of the oyster with its environment and its potential to serve as a vector for disease in humans and other marine organisms.