Gammaretroviruses, novel viruses and pathogenic bacteria in Australian bats with neurological signs, pneumonia and skin lesions

More than 70 bat species are found in mainland Australia, including five species of megabat from a single genus (family Pteropodidae) and more than 65 species representing six families of microbats. The conservation status of these animals varies from least concern to endangered. Research directed at evaluating the impact of microorganisms on bat health has been generally restricted to surveillance for specific pathogens. While most of the current bat virome studies focus on sampling apparently healthy individuals, little is known about the infectome of diseased bats. We performed traditional diagnostic techniques and metatranscriptomic sequencing on tissue samples from 43 individual bats, comprising three flying fox and two microbat species experiencing a range of disease syndromes, including mass mortality, neurological signs, pneumonia and skin lesions. We identified reads from four pathogenic bacteria and two pathogenic fungi, including Pseudomonas aeruginosa in lung samples from flying foxes with peracute pneumonia, and with dermatitis. Of note, we identified the recently discovered Hervey pteropid gammaretrovirus, with evidence of replication consistent with an exogenous virus, in a bat with lymphoid leukemia. In addition, one novel picornavirus, at least three novel astroviruses and bat pegiviruses were identified. We suggest that the most likely cause of peracute lung disease was Pseudomonas aeruginosa, while we suspect Hervey pteropid gammaretrovirus was associated with lymphoid leukemia. It is possible that any of the novel astroviruses could have contributed to the presentation of skin lesions in individual microbats. This study highlights the importance of studying the role of microorganisms in bat health and conservation. ### Competing Interest Statement The authors have declared no competing interest.