Comparative viral metagenomics from chicken feces and farm dust in the Netherlands

Livestock animals housed in close proximity to humans can act as sources or intermediate hosts facilitating animal-to-human transmission of zoonotic diseases. Understanding virus diversity in livestock is important for identifying potential zoonotic threats and for ensuring animal health and safe livestock production. Here, we report viral metagenomic characterization of chicken feces (N=51) and paired farm dust samples (N=13) using metagenomic deep sequencing. Samples were collected at 4-5 time points in three broiler farms in the Netherlands. Viruses in the Parvoviridae and Picornaviridae families were the most prevalent, detected in all feces and dust samples and in all feces and 85% of dust samples, respectively. Virus composition found in chicken feces and corresponding dust samples were similar. Great genomic diversity was identified in Picornaviridae and 46 sequences from five picornavirus genera ( Sicinivirus , Megrivirus , Anatvirus , Gallivirus and Avisvirus ) were detected. For calicivirus, Basovirus and an unclassified novel chicken calicivirus were identified in 13 fecal and 1 dust samples. Two distinct types of chicken astroviruses were identified. Phylogenetic analyses of identified virus sequences from Picornaviridae , Astroviridae and Caliciviridae suggested that viral sequences obtained from different farms are often more closely related to each other than global reference sequences, and sequences from feces and paired dust samples also clustered together. Importantly, our sequencing methodology enabled the recover viral genome sequences from farm dusts, allowing the tracking of virus chatter between livestock animals and their farm environment. This study, albeit relative sample size, does expand current knowledge of virus communities in chickens and surrounding dusts. IMPORTANCE Chickens may harbor various zoonotic pathogens, some of which can cause severe clinical outcomes in animals and humans. Farm dust can act as vector to facilitate zoonoses transmission. Here, we report the metagenomic characterization of virus communities of chicken feces and paired farm dust samples collected at multiple time points during the production cycle in broiler farms in the Netherlands. Parvoviridae and Picornaviridae were most frequently detected. We also identified novel astrovirus and calicivirus sequences that would inform future virus taxonomy classification. This is the first study to characterize virus communities in farmed chickens and paired farm dust samples. We also describe a dust sequencing strategy that can be adapted for future dust metagenomic characterization. Our study could help setting up a surveillance baseline for tracking virus flow between chickens and their farm environment which could guide zoonotic outbreak preparedness and health risk assessment of farm exposure.