The status of Lyssaviruses in Bats of Australia and Melanesia.

Australian Bat Lyssavirus (ABLV) is closely related to rabies virus and has caused human and animal fatalities in Australia. Two variants have been identified, one circulating in flying foxes and the other in the microbat Saccolaimus flaviventris. As surveillance in other Australian microbats has been limited, this project sought to determine whether additional Australian Bat Lyssavirus variants or microbat hosts exist in Australia by testing bats that came into veterinary care and did not survive. Furthermore, given the geographic proximity to Melanesia and the diversity of bat species, the project sought to assess whether ABLV extends into the region by testing museum specimens of bat species from the Solomon Islands.

This project tested >600 sick and/or injured microbats submitted from Queensland, the Northern Territory and Western Australia. ABLV was detected in only one microbat submitted – an S. flaviventris from Far North Queensland. This study found no evidence for additional microbat hosts of ABLVi beyond this species. As some of the bats that came into care in Australia displayed clinical signs consistent with lyssavirus infection, these were tested for other pathogens using deep sequencing. The results showed these microbats in care were predominantly impacted by bacterial pathogens. Viruses belonging to Circoviridae were also detected and to our knowledge this is the first report of a bat-associated circovirus and cyclovirus in Australia.

This project also tested brain tissue from >400 bat specimens from the Solomon Islands. Although no lyssavirus was detected, several bats featured encephalitis and/or parasitic infections, validating the use of museum specimens for pathogen surveillance. Histological examination of brain tissue and deep sequencing of these specimens indicates apicomplexan, bacterial, and viral infections impacting flying foxes in the Western Province of the Solomon Islands.