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Completed Project

Linking Ranavirus Infection Dynamics and Microbiome Diversity in Larval Wood Frogs

Jillian Hornbeck ‘20, Claire Stutzman ‘21, and Professor Myra Hughey

Ranavirus is an infectious viral disease that causes severe mortality in fishes, amphibians, and reptiles. In northeastern North America, ranavirus causes mass die-offs of larval wood frogs (Rana sylvatica), but die-offs are not observed in all locations where wood frogs breed. The microbiome plays a critical role in host health, and, in amphibians, the microbiome appears to play a role in protecting hosts from pathogens. Amphibian populations in Europe that coexist with ranavirus have microbiomes that differ in composition from populations that have experienced die-off events. However, little is known about interactions between ranavirus infection and the microbiome in other parts of the world. We conducted a field survey to assess if variation in the bacterial symbiont communities of larval wood frogs is related to the incidence and severity of ranavirus infections. The survey was conducted at eight ponds on the campus of Vassar College. At each sampling point, we measured pond abiotic conditions: temperature, conductivity, pH, and water depth. Additionally, we collected samples from tadpoles to determine the diversity of the skin and gut bacterial communities and ranavirus infection levels. Samples were collected both before and during observed outbreaks of ranavirus. We found ranavirus at all of our sites and ranavirus-related mortality events were observed at all but one site. The timing and severity of outbreaks differed between ponds—ponds that were more permanent had higher viral loads earlier in the season and, also, experienced earlier outbreaks. Data on bacterial community diversity will be presented.