Characterization of tick viromes collected from dogs in China

In this study,we explored the viral diversity and community structures of the ticks collected from dogs and detected possible tick-borne viruses(TBVs)using metagenomic analysis.Additionally,full-length sequences and the structural,phylogenetic andmolecular features of the possible TBVs were characterized using bioinformatics tools.The sequence run produced 12,254,268 reads and 6,667,259 unique reads from the tick pools.Further analysis of the viral reads revealed that 92.73%were similar to ssRNA viruses,and 90.5%of the total viral sequences belonged to Non-classified viral families.Of the 29 classified viral families,most virome sequenceswere homologouswith vertebrate viruses from Circoviridae,plant viruses from Virgaviridae,phages fromMicroviridae,insect viruses from Baculoviridae,and giant viruses from Mimiviridae.In the process of assembly of reads,large contigs representing four virus families were identified,including Phenuiviridae,Chuviridae,Parvoviridae and Non-classified families.Some sequences of Non-classified family shared a highly divergent amino acid sequence identities from existing virus sequences.The importance of these newly identified virus contigs to public and veterinary health needs additional researches.Because of the lack of the acquired viral reads from these families,we only demonstrated the complete sequences of Circoviridae in detail.The complete canine circovirus(CaCV)-NC21 genome detected from police dogs was 2,063 bp long with a GC content of 53.6%.Our results suggested that tick viromes collected fromdogs contained diverse sequences with a broad range of animal,insect,plant,and phage viruses,which may reflect the ecological characteristics of the dogs and their ticks.Furthermore,our study revealed the existence of the partial contigs belonging to the four virus families in ticks.More researches are needed to verify their importance to public and veterinary health.As well,our detection of CaCv-NC21 demonstrated that ticks can harbor and potentially transmit canine circoviruses.