Molecular characterization of Canis familiaris oral papillomavirus 1 identified in naturally infected dogs from Northeast Brazil.

Background: Canine papillomavirus (CPV) has 20 described types associated with papillomas or squamous cell carcinoma (SCC). Knowledge about CPV diversity is scarce. Studies on papillomaviruses that infect other hosts show substantial diversity with some types and variants being associated with cancer.

Hypothesis/objectives: The aim of this study was to assess the genetic variability of the capsid L1 gene of CPV identified in lesions of naturally infected dogs from Brazil.

Animals: Six dogs presenting with oral and cutaneous warts from different veterinary clinics in Sergipe state, Northeast Brazil.

Methods And Materials: Nine skin biopsy samples were collected for histopathological and molecular analyses. Bioinformatics tools were used for genotyping and diversity analysis. Mutations were characterized based on their impact on the L1 protein structure.

Results: Sequences of CPV1 were obtained from exophytic papillomas. These sequences had at least five different mutations showing that all sequences were putative CPV1 variants. One CPV1 sequence, obtained from an oral SCC, had a highly destabilizing substitution in the L1 protein which was likely to be associated with changes in protein function.

Conclusions And Clinical Importance: Despite the small number of cases analysed and the partial analysis of L1 nucleotide and amino acid sequences, this study has demonstrated diversity in CPV samples from Northeast Brazil. A putative new CPV1 variant associated with oral SCC, with novel protein structure changing mutations, was identified which may be important for understanding papillomavirus pathogenesis.