Oral Presentation Lorne Infection and Immunity 2021

Infectious KoRV-related retroviruses circulating in Australian bats (#6)

Joshua A Hayward 1 2 , Mary Tachedjian 3 , Claudia Kohl 4 , Adam Johnson 1 , Megan Dearnley 3 , Brianna Jesaveluk 1 , Christine Langer 1 , Philip D Solymosi 4 , Georg Hille 4 , Andreas Nitsche 4 , Cecilia A Sánchez 3 5 6 , Adam Werner 1 , Dimitri Kontos 1 , Gary Crameri 3 , Glenn A Marsh 3 , Michelle L Baker 3 , Pantelis Poumbourios 1 , Heidi E Drummer 1 , Edward C Holmes 7 , Lin-Fa Wang 8 , Ina Smith 3 , Gilda Tachedjian 1 2 9
  1. Life Sciences, Disease Elimination, Burnet Institute, Melbourne, VIC, Australia
  2. Department of Microbiology, Monash University, Melbourne, VIC, Australia
  3. Australian Centre for Disease Preparedness, Commonwealth Scientific and Industrial Reseach Organisation, Geelong, VIC, Australia
  4. Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, Germany
  5. Odum School of Ecology, University of Georgia, Athens, Georgia, USA
  6. Center for the Ecology of Infectious Diseases, University of Georgia, Athens, Georgia, USA
  7. School of Life and Environmental Sciences and Sydney Medical School, University of Sydney, Sydney, NSW, Australia
  8. Emerging Infectious Disease Program, Duke-NUS Graduate Medical School, Singapore
  9. Department of Microbiology and Immunology at the Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia

Bats are reservoirs of emerging viruses that are highly pathogenic to other mammals including humans. Despite the diversity and abundance of bat viruses, they had previously not been shown to harbor exogenous retroviruses. Here we report the discovery and characterisation of a group of Koala retrovirus-related (KoRV-related) gammaretroviruses in Australian and Asian bats (1). These include the Hervey pteropid gammaretrovirus (HPG), the first reproduction-competent retrovirus found in bats, a close relative of KoRV and the Gibbon ape leukemia virus (GALV). The host animals of KoRV (koalas) and GALV (gibbons) respectively exist in non-overlapping habitats in Australia and Asia, separated by an oceanic boundary.      

In this study we extracted and assembled the complete HPG genome from the scat of a single black flying fox, captured in Hervey Bay (QLD). We then chemically synthesized a proviral molecular clone that is capable of generating reproduction-competent virions. Electron microscopy and virion-associated reverse transcriptase (RT) assays reveal that HPG has the virion morphology and Mn2+-dependent RT activity typical of a gammaretrovirus, and that in vitro, HPG is capable of infecting bat and human cells, but not mouse cells. Through an envelope protein pseudotyping assay, HPG displays a similar pattern of cell tropism as KoRV-A and GALV. Population studies reveal the presence of HPG and KoRV-related sequences in several locations across north-east Australia, as well as serological evidence for HPG in multiple pteropid bat species.

Combined, these results reveal bats to be important reservoirs of KoRV-related gammaretroviruses that can potentially be transmitted to other mammalian species, and positions bats as the most likely transmitters of KoRV-related retroviruses between Asia and Australia.

  1. Hayward, J. A., et al. (2020). "Infectious KoRV-related retroviruses circulating in Australian bats." Proceedings of the National Academy of Sciences 117(17): 9529-9536.