Meeting Abstract

P3.120  Wednesday, Jan. 6  Escape from the pond: Stress response to ranavirus infection in wood frogs WARNE, R.W.*; CRESPI, E.J.; BRUNNER, J.L.; Vassar College, NY; Vassar College, NY; State University of New York, Syracuse rw.warne@gmail.com

Ranaviruses are widespread, directly transmitted viruses of ectothermic vertebrates that cause mass die-offs in amphibians. Despite these often dramatic and lethal impacts, little is known about how amphibian physiology mediates ranavirus infection. In an LD-50 experiment, in which prometamorphic wood frog tadpoles (Rana sylvatica) were infected with varying doses of a ranavirus isolated from a recent frog die-off in the Hudson Valley, NY, we found that the odds of dying increased with Gosner stage at the time of exposure. Because glucocorticoids (CORT) play an important role in both regulating metamorphic development, as well as the mounting of an immune response, we hypothesized that virus infected tadpoles would exhibit increased levels of CORT relative to controls. Here we test this hypothesis through examination of development and the daily CORT profile of tadpoles infected with ranavirus over 6 days relative to uninfected tadpoles. We found that development, measured as progression through Gosner stages, was significantly faster in infected tadpoles relative to controls. Infected tadpoles in advanced developmental stages also had significantly lower body condition relative to controls at the same stage. These results suggest that elevated CORT levels needed to mount an immune response may also drive increased development rates at a cost to nutritive condition. From a life history perspective, the advancement of development may also provide a mechanism by which tadpoles could escape a pond with an epidemic ranavirus outbreak. These results provide basic insight into the physiological mechanisms by which amphibians mediate the costs of immune function and survival in the face of emerging infectious diseases.