Viral diversity in synanthropic birds of Southwestern Siberia.

Infectious diseases in birds represent a significant threat to poultry economies, wild bird biodiversity, and public health, underscoring the importance of surveillance within a One Health framework. Synanthropic birds, which live in close proximity to humans and domestic animals, can act as crucial bridge hosts for viral transmission between wild and domestic populations. This study aimed to assess the prevalence and diversity of four key viral families—Orthomyxoviridae, Paramyxoviridae, Coronaviridae, and Astroviridae—in synanthropic birds from the south of Western Siberia, an important convergence zone of major migratory flyways for many bird species. Using molecular detection methods, we identified avian coronaviruses (ACoV) and avastroviruses (AAstV), but found no evidence of avian influenza virus (AIV) or avian paramyxoviruses (APMV). Overall, 3.8% of birds tested positive for at least one of the studied viruses, with ACoV detected in 1.4% and AAstV in 2.4% of samples. Phylogenetic analysis revealed that the detected coronaviruses belong to the genus Deltacoronavirus and form a distinct clade with a previously identified virus from North Siberia, suggesting a stable, regional corvid-associated lineage. The detected astroviruses were highly diverse, falling within a broad group of unclassified passerine-associated avastroviruses with phylogenetic links to viruses from Kazakhstan and China, reflecting the region's role as a migratory crossroads. The absence of AIV and APMV may reflect low prevalence at the time of sampling or host-specific factors like low susceptibility or immunocompetence that suppress viral replication. These findings highlight that synanthropic birds in this key ecological region harbor novel and diverse viruses and represent important, though often overlooked, subjects for expanding our understanding of viral diversity in surveillance programs.