Bat species tolerant and susceptible to fungal infection show transcriptomic differences in late hibernation and healing

Much of the research into white-nose disease has focused on the hibernation period, while the pathogenic fungus Pseudogymnoascus destructans is actively infecting the bat host. Previous research has found large differences between the susceptible North American Myotis lucifugus and the tolerant European Myotis myotis, suggestive of immunopathology in the former, and a beneficial lack of strong response in the latter. Here, we examined gene expression in these species both during the late-hibernation period and a month after emergence from hibernation, during healing from infection. We utilised paired sampling, collecting wing tissue that was positive and negative for fungal infection fluorescence, to examine changes in whole-transcriptome gene expression that were local to sites of infection at two time points: pre-emergence and 30 days post-emergence from hibernation. Positive samples were contrasted between the two time points to examine longitudinal changes. During the pre-emergence period, local inflammatory responses were observed in both M. myotis and M. lucifugus. Immune responses between the tolerant and susceptible species were dissimilar, favouring Th1 and Th17 cytokine responses, respectively. This lends weight to immunopathology as a contributing factor to mortality in M. lucifugus. Continual immune responses may not only contribute to immunopathology and host mortality but also have important carry-over effects on reproduction and subsequent pre-winter fattening, affecting population viability over a longer period of time than previously considered.