Host cell tropism, genome characterization, and evolutionary features of OaPV4, a novel Deltapapillomavirus identified in sheep fibropapilloma

- OaPV4 is a Deltapillomavirus 3 able to infect both epithelial cells and fibroblasts.
- OaPV4 genome full sequence and organization allow identifying OaPV1 as the closest relative.
- Phylogeny and divergence times provide indication for early speciation of ovine PVs.
- OaPV4 discovery allowed reviewing main biological features of ovine PVs.
- Findings are relevant to PV evolution and add up to biology, pathology, and evolution knowledge of animal PVs.

Investigating papillomavirus (PV) diversity is crucial to fully comprehend pathogenicity, genetic features, and evolution of taxa hosted by domestic and wild animal species. This study reports the identification of OaPV4, a novel ovine PV type within Deltapapillomaviruses 3. The study of OaPV4 genomic features combined to in situ hybridization and immunohistochemistry investigations allowed extrapolating several general biological features of ovine PVs, such as their cellular tropism, pathogenicity, and evolutionary history. Based on results, ovine PVs can be grouped into a polyphyletic ancient group of viruses, which splits in two main subgroups having peculiar cellular tropism and pathogenicity. Results add up to animal PV diversity and are crucial to future studies aimed to investigate the correlation between animal PV and cutaneous benign and malign proliferations.