Available online 17 September 2021, 200226

This is the first report of Equus caballus papillomavirus 2 (EcPV2) identified from equine genital squamous cell carcinoma (SCC) in Asia.

This report also serves to emphasize the importance of EcPV2 in vulvar neoplasia, which is less commonly recognized than EcPV-2-induced penile or preputial neoplasia.

Histopathologically, the SCC described in this mare was an unusual acantholytic variant that has not been reported previously in horses.

Equus caballus papillomavirus type 2 (EcPV2) infection has been associated with genital squamous cell carcinoma (SCC) development in horses. However, very few reports on EcPV2-associated disease in Asia exist. Our study characterizes pathological and virological features of an EcPV2-associated vulvar SCC from a Japanese mare. Conventional PCR, in situ hybridization, reverse-transcriptase PCR and immunohistochemistry confirmed the presence and distribution of EcPV2 within the lesion and suggested that p53 degradation may not be the mechanism by which this virus induces neoplastic transformation. The complete viral sequence in this Japanese case shows near perfect sequence homology with European reference strains of EcPV2, which may be useful when considering the target for future EcPV2 vaccine development. This report also serves to highlight the importance of EcPV2 in female (vulvar) neoplasia, which is less commonly recognized than EcPV2-induced male (penile or preputial) neoplasia. Finally, the SCC described in this mare was an unusual acantholytic variant that has not been reported previously in horses. It is the first report of EcPV2 identified from genital SCC in Asia and underscores the likely worldwide distribution of this virus and its consistent association with equine genital neoplasia.

EcPV2

genital

vulva

papillomavirus

carcinoma

SCC

© 2021 The Authors. Published by Elsevier B.V.