Immune responses in hibernating little brown myotis () with white-nose syndrome.

White-nose syndrome (WNS) is a fungal disease responsible for decimating many bat populations in North America. (), the psychrophilic fungus responsible for WNS, prospers in the winter habitat of many hibernating bat species. The immune response that elicits in bats is not yet fully understood; antibodies are produced in response to infection by , but they may not be protective and indeed may be harmful. To understand how bats respond to infection during hibernation, we studied the effect of inoculation on the survival and gene expression of captive hibernating with varying pre-hibernation antifungal antibody titres. We investigated gene expression through the transcription of selected cytokine genes (, , , and ) associated with inflammatory, Th1, Th2 and Th17 immune responses in wing tissue and lymph nodes. We found no difference in survival between bats with low and high anti- titres, although anti- antibody production during hibernation differed significantly between infected and uninfected bats. Transcription of and was higher in the lymph nodes of infected bats compared with uninfected bats. Increased transcription of these cytokines in the lymph node suggests that a pro-inflammatory immune response to WNS is not restricted to infected tissues and occurs during hibernation. The resulting Th17 response may be protective in euthermic bats, but because it may disrupt torpor, it could be detrimental during hibernation.