A novel lineage of polyomaviruses identified in bark scorpions

Polyomaviruses are non–enveloped viruses with circular double-stranded DNA genomes that range in size from ∼4–7 kilobasepairs. Initially identified in mammals, polyomaviruses have now been identified in birds and a few fish species. Although fragmentary polyomavirus-like sequences have been detected as apparent ‘hitchhikers’ in shotgun genomics datasets for various arthropods, the possible diversity of these viruses in invertebrates remains unclear. In general, polyomaviruses are host-specific, showing strong evidence of host-virus co–evolution. Identification of polyomaviruses in a broader range of animals could shed useful light on the evolutionary history of this medically important group of viruses. Scorpions are predatory arachnids that are among the oldest terrestrial animals. Thus far, viromes of arachnids have been under–sampled and understudied. Here, high–throughput sequencing and traditional molecular techniques were used to explore the diversity of circular DNA viruses associated with bark scorpions ( Centruroides sculpturatus ) from the greater Phoenix area, Arizona, USA. The complete genomes of eight novel polyomaviruses were identified. Analysis of Centruroides transcriptomic datasets elucidated the splicing of the viral late gene array, which is more complex than that of vertebrate polyomaviruses. Phylogenetic analysis provides further evidence of co-divergence of polyomaviruses with their hosts, suggesting that at least one ancestral species of polyomaviruses was circulating amongst the primitive common ancestors of arthropods and chordates.