Monster Seminar JAM - The influence of a viral hyperparasite on withering syndrome, a rickettsial disease of abalone
Dr. Carolyn Friedman, School of Aquatic and Fishery Sciences, University of Washington
Withering Syndrome, WS, is a bacterial disease of abalone caused by a Rickettsia-like organism, WS-RLO, resulting in up to 99% losses of black abalone in central and southern California, including San Nicolas Island, SNI. Since 2002, abalone densities have increased 2.5x compared to the minimum in 2001. We exposed juvenile black abalone from SNI (WS selection) and Carmel (no WS selection) to RLO-infected red abalone and monitored them for 17mo. More exposed abalone from Carmel died from WS than did those from SNI (p<0.05), while no differences in survival were observed between control groups (p>0.05). Microscopic examination suggests that resistance may be more related to the host response to initial infection than to the ability to resist infection. During this study, we observed what appeared to be a novel bacterium, morphologically distinct from but shares the same tissue tropism as the WS-RLO. Electron microscopic examination suggests that the novel-RLO may be the WS-bacterium infected with a phage hyperparasite. Based on a second study in which these same groups of abalone were exposed only to WS-RLO, similar losses were observed in both groups after only 7 mo. These data further illustrate disease resistance in the SNI populations but also suggest that phage infection may reduce pathogenicity and dampen losses with the WS-RLO.
Date and Time:
February 10, 2011,
11:00 am - 12:00 pm