Molecular cloning and characterization of a novel human papillomavirus, HPV 126, isolated from a flat wart-like lesion with intracytoplasmic inclusion bodies and a peculiar distribution of Ki-67 and p53

Infection with certain human papillomavirus types induces warts with specific macroscopic and microscopic features. We observed multiple flat wart-like lesions on the chest, neck and extremities of an adult T-cell leukemia patient. Histologically, atypical intracytoplasmic inclusion bodies currently known to be pathognomonic for genus gamma or mu papillomaviruses were disclosed in some cells of the epidermis showing histological features compatible with flat warts. In the present study, a novel human papillomavirus was identified and its whole genome, 7326 bp in length, was cloned and characterized. Phylogenetic analysis showed the virus designated as HPV126 to be a novel type of genus gamma papillomavirus. Strikingly, Ki-67 and p53 expression was found to be increased in all layers of the epidermis except for horny layer, contrasting to expression restricted to the basal and lower spinous layers in ordinary flat warts.

► We cloned the whole genome of a novel species of gamma papillomavirus, HPV126. ► HPV126 was isolated from a flat wart-like lesion of an ATL patient. ► Homogeneous intracytoplasmic inclusion bodies were observed in the lesions. ► Strong staining of Ki-67 and p53 was observed in broad layers of the epithelium. ► This is the first report of a link between a gamma papillomavirus and flat warts.