Rodents as potential reservoirs for toroviruses.

Background: Emerging zoonotic viruses pose a significant threat to global health. The order Nidovirales includes diverse viruses, such as coronaviruses, which are well known for their zoonotic potential. Toroviruses are a less-studied genus within Nidovirales primarily associated with gastrointestinal diseases in ungulates, although some evidence suggests their presence in humans.

Methods: We set out to describe full-length genomes of potentially emerging viruses by collecting feces from dozens of small mammals, mainly rodents, captured in different regions of Spain. Viral reads were obtained by high-throughput Illumina sequencing and analyzed phylogenetically.

Results: In this study, we report the discovery of a novel torovirus from a fecal sample of a dormouse (Eliomys quercinus) in Spain, which we named Dormouse torovirus (DToV). This represents the first complete genome of a rodent-associated torovirus. The 28,555-nucleotide genome encodes the six characteristic torovirus open reading frames, but these exhibit low amino acid sequence identity (44.3-86.3%) compared to other toroviruses, indicating that DToV likely represents a new viral species. Moreover, the basal phylogenetic position of DToV suggests that rodents may represent a reservoir for this viral genus.

Conclusions: Our findings expand the known torovirus host range, underscore their potential for cross-species transmission, and highlight the importance of continued surveillance of wildlife viruses.