Genetic analysis of bovine papular stomatitis and pseudocowpox viruses circulating in Hokkaido, Japan's largest cattle-producing region.

Abstract

Parapoxvirus infections caused by bovine papular stomatitis virus (BPSV) and pseudocowpox virus (PCPV) are globally distributed zoonoses in ruminants. Although parapoxviruses have been isolated and genetically characterized in several regions of Japan, no sequence data are available from Hokkaido, which has the country's largest cattle population. Consequently, the genetic characteristics of strains circulating in Hokkaido remain unclear. This study analyzed the genetic relationships and molecular epidemiology of 11 BPSV and two PCPV strains isolated in Hokkaido between 2005 and 2022. Full-length sequences of open reading frames (ORF) 11 and 32 were determined and compared with previously reported strains. The deduced amino acid identities of ORF11 ranged from 95 to 100% among 11 BPSV strains and 98% between the two PCPV strains. ORF32 amino acid identities among BPSV strains ranged from 88% to 100%. This study reports the first ORF32 sequences of Japanese parapoxviruses. Phylogenetic analysis based on ORF11 showed that 10 BPSV strains formed a single cluster, whereas one strain was distinct; the two PCPV strains also formed separate clusters. ORF32 analysis indicated that most BPSV strains clustered together, except for one strain with an amino acid deletion. Comparisons with domestic and foreign strains demonstrated that ORF11 is highly conserved, whereas ORF32 exhibits greater genetic diversity, supporting its suitability for molecular epidemiological analysis. These findings indicate that genetically related parapoxviruses are circulating in Hokkaido.