Water Temperature Affects Susceptibility to Ranavirus.
The occurrence of emerging infectious diseases in wildlife populations is increasing, and changes in environmental conditions have been hypothesized as a potential driver. For example, warmer ambient temperatures might favor pathogens by providing more ideal conditions for propagation or by stressing hosts. Our objective was to determine if water temperature played a role in the pathogenicity of an emerging pathogen (ranavirus) that infects ectothermic vertebrate species. We exposed larvae of four amphibian species to a Frog Virus 3 (FV3)-like ranavirus at two temperatures (10 and 25°C). We found that FV3 copies in tissues and mortality due to ranaviral disease were greater at 25°C than at 10°C for all species. In a second experiment with wood frogs (Lithobates sylvaticus), we found that a 2°C change (10 vs. 12°C) affected ranaviral disease outcomes, with greater infection and mortality at 12°C. There was evidence that 10°C stressed Cope's gray tree frog (Hyla chrysoscelis) larvae, which is a species that breeds during summer-all individuals died at this temperature, but only 10% tested positive for FV3 infection. The greater pathogenicity of FV3 at 25°C might be related to faster viral replication, which in vitro studies have reported previously. Colder temperatures also may decrease systemic infection by reducing blood circulation and the proportion of phagocytes, which are known to disseminate FV3 through the body. Collectively, our results indicate that water temperature during larval development may play a role in the emergence of ranaviruses.
Department of Biomedical and Diagnostic Services, College of Veterinary Medicine, University of Tennessee Institute of Agriculture, Knoxville, TN, USA.
Mabre D
MD
Brand
Center for Wildlife Health, University of Tennessee Institute of Agriculture, Knoxville, TN, USA.
Rachel D
RD
Hill
Department of Biology, Carroll University, Waukesha, WI, USA.
Roberto
R
Brenes
Center for Wildlife Health, University of Tennessee Institute of Agriculture, Knoxville, TN, USA.
Jordan C
JC
Chaney
Veterinary Diagnostic and Investigational Laboratory, University of Georgia, Tifton, GA, USA.
Rebecca P
RP
Wilkes
Department of Biological Sciences, George Washington University, Washington, DC, USA.
Leon
L
Grayfer
Department of Biomedical and Diagnostic Services, College of Veterinary Medicine, University of Tennessee Institute of Agriculture, Knoxville, TN, USA.|Center for Wildlife Health, University of Tennessee Institute of Agriculture, Knoxville, TN, USA.
Debra L
DL
Miller
Center for Wildlife Health, University of Tennessee Institute of Agriculture, Knoxville, TN, USA. mgray11@utk.edu.
Matthew J
MJ
Gray
D000818:Animals; D004266:DNA Virus Infections; D004198:Disease Susceptibility; D017995:Ranavirus / Q000472:pathogenicity*; D011898:Ranidae / Q000821:virology*; D013696:Temperature; D014867:Water
D014867:Water
amphibians; climate change; disease; pathogen; ranavirus; temperature