Microbiomes and zoonoses: dynamics of the black flying fox (Pteropus alecto) gastrointestinal microbiome

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Montana State University - Bozeman, College of Agriculture


Land-use change is increasingly recognized as a driver of spillover of zoonotic pathogens. Australian black flying foxes (Pteropus alecto) are experiencing extensive loss of habitat which reduces available food, particularly in winter. Hendra virus (HeV, family: Paramyxoviridae) was isolated from horses and humans in 1994 and P. alecto was later identified as the reservoir host. As habitat loss threatens these bat populations, and Hendra virus continues to spill over to horses annually, it is important to understand factors that influence bat health and viral shedding. Because gastrointestinal tract (GIT) microbiomes are important for host health and are understudied in flying foxes, the goal of this research was to understand the natural dynamics of the P. alecto GIT microbiome and its associations with diet, body composition, markers of inflammation, and viral shedding. We sampled Pteropus alecto near Brisbane from 2018-2020. We captured bats returning from foraging and collected rectal swabs to determine the GIT microbiome using 16S rRNA amplicon sequencing. In addition to feces for dietary analysis, we also collected samples to measure health and infection, including blood to measure neutrophil-to-lymphocyte ratios, urine to detect Hendra virus, and bioelectrical impedance analysis to measure body fat. These data enabled us to determine how the P. alecto GIT microbiome varied within individuals over time and in the context of physiological, ecological, and dietary shifts. Lastly, we asked if we could predict health outcomes using the GIT microbiome. We found that P. alecto GIT microbiomes are highly dynamic over time, through different life stages, between foraging strategies, and that the type of diet is associated with GIT microbiome diversity. Bats consuming native foods had lower GIT microbiome diversity compared to those consuming introduced and cultivated foods. Despite associations between body fat and HeV infection, the GIT microbiome was not able to predict these health outcomes. These results suggest that P. alecto GIT microbiomes are highly dynamic and may not contribute significantly to host health. Future research should incorporate more health metrics or other approaches to microbiome profiling to determine if the GIT microbiome could be used as a biomarker of health.




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