Papillomavirus-Associated Focal Oral Hyperplasia in Wild and Captive Asian Lions (Panthera leo persica)

Abstract

Four Asian lions (Panthera leo persica), two wild and two captive, were diagnosed with focal oral hyperplasia affecting the ventral surface of their tongues. Focal, flat, sessile lesions consisted of hyperplastic, stratified squamous epithelium. Koilocytotic atypia was evident in the upper layers of cells, some of which contained characteristic intranuclear papillomavirus particles visible by electron microscopy. In addition, large amphophilic cytoplasmic inclusions were evident in the koilocytes and were considered to be a product of the viral E4 gene. Papillomavirus group-specific antigens were detected by immunohistochemistry in the atypical cell nuclei. Conserved papillomavirus antigenic epitopes differed from epitopes found in cutaneous papillomavirus-induced lesions from domestic cats. An 8,000-base pair DNA fragment, linearized by Bam HI digestion, was detected by Southern blot hybridization probed with a mixed human papillomavirus genomic probe. Limited restriction endonuclease studies of DNA prepared using an oral hyperplastic lesion from an Asian lion indicate that this is a novel feline papillomavirus different from the domestic cat cutaneous papillomavirus. This new virus has been designated "P1PV".