Identification and characterization of a novel Taupapillomavirus strain in lymphoid tissue of a stray dog.

In this study, viral metagenomic approach was employed to identify a novel canine papillomavirus (CPV) strain in the lymphoid tissue of a stray dog. The complete circular genome (8,297 bp) of a novel papillomavirus strain, designated canpapil01, was characterized and taxonomically assigned to the genus Taupapillomavirus. The genome encodes five early genes (E1, E2, E4, E6, E7) and two late genes (L1 and L2), lacking the E5 gene. Conserved motifs essential for viral replication and host interaction were identified, including ATP-binding and cyclin interaction sites in E1, DNA-binding domains in E2, and zinc-binding domains in E6 and E7. Notably, the pRb-binding motif (LXCXE) was absent in E7. The long control region (LCR) contained predicted E1 and E2-binding sites, indicating regulatory functions. Phylogenetic analysis based on the L1 gene revealed that canpapil01 clustered with Taupapillomavirus 2 strains, which were isolated from nasal swab or blood samples of dogs and wolves in the Switzerland and the USA, forming a separate branch. Genome-wide comparisons showed 71.4% amino acid identity with the Taupapillomavirus 2 reference strain (NC_040578), confirming it as a novel strain within this species. These findings expand the known genetic diversity of canine papillomaviruses and provide valuable genomic data for future research into CPV-associated diseases.