The dynamics of microbiome and virome in migratory birds of southwest China.

Migratory birds carry pathogens, posing a significant threat to environmental and human health. We documented the metatranscriptome and RNA virome of 896 stool samples from migratory birds and environmental samples over four consecutive years in southwest China. Our analysis identified Catellicoccus marimammalium as the predominant bacterium in the gut of black-headed gulls, with an average relative abundance of 79.3%. Strain-level analysis of C. marimammalium revealed a dominant population with some longitudinal diversity over the four years. Additionally, the gut of black-headed gulls was found to harbor numerous viruses, including a novel hepatovirus. Lysates of cells of C. marimammalium but not other bacteria derived from black-headed gulls could inhibit the replication of human hepatovirus, suggesting a potential regulatory role for gut commensal bacteria in modulating viral carriage. These findings enhance our understanding of the microbiome and RNA virome diversity in migratory birds and provide insights into the modulation of asymptomatic infections.