Long term circulation of avian paramyxovirus 4 in Australia revealed by historical and contemporary genomes from wild and domestic birds.

Avian paramyxovirus 4 (APMV4) is detected sporadically in wild birds and poultry, globally. While predominantly detected in waterfowl, the natural reservoir and ecology of APMV4 remains unclear. Herein we report historical and contemporary detections of APMV4 in Australia, and through sequencing demonstrate the likely long-term presence in a diversity of Australian wild bird species. This is evidenced by contemporary Australian genome sequences being more similar to historical Australian genomes rather than contemporary Asian genomes and that these genomes form a single lineage. This suggests that APMV4 has been circulating on the continent for decades. While APMV4 has demonstrable, albeit sporadic, impact on poultry globally, there has never been a report of this virus causing disease in poultry in Australia, suggesting it likely continues to pose a low risk for the poultry industry. As wild birds serve as natural reservoirs for numerous viruses of potential concern to poultry, dedicated surveillance is critical for revealing the risk profile of wild bird viruses, such as APMV4, to poultry.