Meeting Abstract
The fungal pathogen Batrachochytrium dendrobatidis (Bd) infects amphibians and can cause the disease chytridiomycosis. Bd-associated population declines have been reported worldwide, and research into the mechanisms underlying Bd susceptibility is needed. It is thought that long-term exposure to environmental stressors suppresses immunity via release of the stress hormone corticosterone (CORT), thus exacerbating the virulence and lethality of Bd. Therefore, we hypothesized that a repeated elevation of plasma CORT would increase Bd susceptibility and chytridiomycosis development in red-legged salamanders. Plasma CORT was exogenously elevated in animals for 7 consecutive days using dermal patches, then animals were inoculated with sub-lethal doses of Bd or vehicle, after which CORT was elevated for another 7 days. Compared to animals inoculated with vehicle, those inoculated with Bd had similar levels of activity, body weight change and mortality. However, Bd-inoculated animals sloughed their skin much more than control inoculated animals. Furthermore, Bd-treated animals with elevated CORT showed significantly more skin sloughing than Bd-treated animals exposed to oil patches. Skin sloughing may represent a mechanism for eliminating Bd infections. The effects of CORT on infection load, measured using real-time qPCR of skin swabs, will also be presented.
