Plasma microRNA Profiles of Myotis lucifugus from a White-Nose Syndrome-affected Population

Abstract

White-nose syndrome (WNS), caused by the fungus Pseudogymnoascus destructans (Pd), has devastated bat populations across North America by disrupting torpor, accelerating fat depletion, and causing severe winter mortality. Surviving populations of little brown bats (Myotis lucifugus) exhibit altered fat storage and adaptive physiological responses, suggesting potential mechanisms for WNS resistance or tolerance. MicroRNAs (miRNAs) are small, non-coding RNA molecules regulating gene expression that play critical roles in metabolic and immune pathways essential for hibernation physiology and pathogen defense. My thesis integrates insilico analyses and experimental validation to evaluate the role of miRNAs in hibernation physiology to establish a novel, non-lethal method for monitoring bat health. Using DIANA miRPath and a targeted literature review, I identified four miRNAs (miR-543, miR-27a, miR-92b, and miR-328) implicated in metabolic and immune pathways relevant to WNS, including lipogenesis, insulin signaling, and FOXO-mediated stress response. I quantified the presence and seasonal expression patterns of selected miRNAs using reverse transcription quantitative real-time PCR in plasma samples collected from WNS-affected bats during fall pre-hibernation and spring emergence. miR-27a-5p and miR-92b-5p showed increased expression in spring compared to fall, and miR-27a-5p correlated positively with Pd fungal load, suggesting its potential as a biomarker for WNS severity. miR-26a-5p was consistently stable across seasons and conditions and was used as a robust endogenous control for plasma-based miRNA studies. This study is the first to demonstrate stable detection and seasonal variation of circulating miRNAs in plasma from free-ranging little brown bats, and one of only a handful to quantify plasma miRNA levels in any of the nearly 1500 bat species, establishing a novel, non-lethal method for monitoring bat health. Future studies should validate gene targets and assess how miRNA expression varies with host physiological state and hibernation conditions. Importantly, this approach could guide targeted management interventions by enabling early identification of vulnerable populations or individuals. Ultimately, the ability to monitor bat health non-lethally, using plasma miRNAs, offers significant potential to enhance wildlife disease surveillance, guide conservation strategies, and contribute to the broader effort of mitigating WNS impacts across North America.Natural Sciences and Engineering Research Council (NSERC, Canada) Discovery Grant to Dr. Craig Willis; Research Manitoba MSc Studentship; University of Winnipeg Graduate Studies ScholarshipMaster of Science in Bioscience, Technology, and Public Polic