Isolation of equine papillomavirus type 1 from racing horse in Japan.

Although many studies have been conducted worldwide for Equus caballus papillomavirus (EcPV), limited information is available on the virus in Japan. We recently collected one classical viral papillomatosis sample (E150904) from a racing horse in Japan. Papillomavirus infection was confirmed by histopathology, immunohistochemistry and PCR assays, and the sample was diagnosed as epithelial papilloma. Full-length genome of the virus was cloned and sequenced. It was 7,613 bp in length and had the same genome organization with reported EcPV-1. Moreover, phylogenetic analysis based on L1 gene revealed that the infection was caused by a variant of EcPV-1. This is the first report of EcPV infection in Japan, and would further contribute to the molecular epidemiological and pathological studies for EcPV.