Background: More than 100 HPVs have been fully characterized, and phylogenetically classified into genera and species based on nucleotide sequence homology. Infection with certain human papillomavirus types induces warts with specific macroscopic and microscopic features. Epidermodysplasia-Verruciformis (EV) is a genodermatosis characterized by widespread and persistent cutaneus lesions caused by beta-papillomaviruses. Rare cases of acquired EV-like eruption associated with beta-papillomavirus infection have been reported.

Objectives: We report a 56-year-old man, who was in the immunocompromised status with adult T-cell leukemia (ATL), had EV-like eruption in chest, neck and extremities. Histologically, there were the typical histological feature of EV and some areas disclosed presence of characteristic homogenous intracytoplasmic inclusion bodies, which is the characteristic feature of gamma-papillomavirus (especially in HPV 60). So, we tried to determine the causative HPV type.

Methods and Results: Although beta-papillomavirus was not detected by highly sensitive polymerase chain reaction (PCR) and mu-papillomavirus, which also shows characteristic intracytoplasmic inclusion bodies, was not detected by PCR, a segment of a putatively novel type of HPV was amplified by gamma-papillomavirus-specific primers (Dermatology 219:274-8, 2009). The entire HPV genome was amplified by PCR and the independent clones were sequenced to avoid PCR errors. Phylogenetic analysis of the sequence data indicated that the virus is a novel type of gamma-papillomavirus (assigned as HPV126). The HPV 126 genome consists of 7326 base pairs and has seven ORFs, potentially encoding the genes E6, E7, E1, E2, E4, L2 and L1. None of any similarity with known E5 genes was shown, which is a characteristic feature of gamma-papillomaviruses.

Conclusion: We identified a novel type of human papillomavirus (HPV 126). HPV 126 showed distinct intracytoplasmic inclusion bodies like other gamma-papillomaviruses. This is the first documentation of an association between EV-like eruption and gamma-papillomavirus infection.