THE PERFORMANCE OF OYSTER FAMILIES EXPOSED TO DERMO DISEASE IS CONTINGENT ON THE SOURCE OF PATHOGEN EXPOSURE  

Dina A. Proestou*, Tal Ben-Horin, Jessica Moss Small, and Standish K. Allen Jr.
 
USDA Agricultural Research Service Northeast Area
National Cold Water Marine Aquaculture Center
Shellfish Genetics Laboratory
Kingston, RI 02881
Dina.Proestou@ars.usda.gov

Here we report preliminary results from a course of research integrating pathology, feeding ecology, genetics and genomics to address resistance to Dermo disease in eastern oysters. We challenged six oyster families with Perkinsus marinus, the etiological agent of Dermo disease, through either direct injection or feeding. These families were derived from dams determined to be either resistant or susceptible to the parasite in a previous study crossed with sires from either selected lines (hANA, CROSBreed) or the unselected line (WTS).  We sampled mortality daily, and to explore variability in the host immune response and disease progression, we censored oysters for transcriptome and disease analyses at four time points (6hr, 36hr, 7d, 28d) following initial exposure. All animals were sacrificed on day 42 of the experiment. As expected, we found the mortality hazard was greatest in oysters exposed to P. marinus through direct injection. In this group, the mortality hazard was greatest in families with sires originating from CROSBreed and WTS lines while predicted dam susceptibility had no effect.  In contrast, when exposed to P. marinus occurred through feeding sire had no effect on mortality. Here, mortality in families with Dermo-susceptible dams was over four times that of families with a resistant dam. These counterintuitive results implicate a range of processes that are likely to vary among individuals and collectively shape the ability for oyster hosts to resist and/or tolerate pathogens. Our upcoming analysis of transcriptomic and disease progression data will yield crucial insights into these complex patterns of Dermo resistance in oysters.