Genomic Characterization of a Novel Victorivirus Detected in a Sample Derived From a Human-Biting Tick in Japan

Surveillance of tick-associated viruses may contribute to our understanding of viral diversity and evolution. Here, we identified a novel victorivirus in a sample derived from a human-biting tick, Amblyomma testudinarium, in Japan. The viral sequence was identified by metatranscriptomic sequencing of total RNA extracted from Vero cells treated with tick homogenate. The viral sequence was 4621 bp in length and contained two major open reading frames predicted to encode a putative coat protein (CP) and a putative RNA-dependent RNA polymerase (RdRp), respectively. The two open reading frames overlapped at the tetranucleotide sequence AUGA. The C-terminal region of putative CP was enriched in alanine, glycine, and proline residues. All these features are similar to those commonly observed in victoriviruses. Phylogenetic analyses based on the amino acid sequences of the putative CP and RdRp showed that the virus belongs to the genus Victorivirus of the family Pseudototiviridae. We therefore designated this putative virus as Amblyomma testudinarium-associated victorivirus 1 (ATaVV1). These findings expand our current knowledge of hidden viral diversity in tick-associated samples.