How may β-genus HPVs contribute to nonmelanoma skin cancer development?
β-HPVs comprise a similarly large group of HPVs. The most extensively studied are HPV5 and HPV8. These are associated with EV, a rare skin disease that can eventually progress to squamous cell carcinoma, particularly in sun-exposed areas of the body. Infection with HPV5 or HPV8 is not sufficient for EV development, and individuals are genetically predisposed to developing this condition. It is an autosomal recessive, genetically heterogeneous disease, and loci on the X chromosome—17q25 (EV1) and 2p21-p24 (EV2)—have been implicated. Two candidate genes for EV1 on 17q25, EVER1 and EVER2, have been identified. It is likely that EV patients cannot effectively control or clear β-genus HPV infections (reviewed by Orth, 2006). The importance of immune surveillances to control β-HPV-associated disease and cancer is supported by the finding that the incidence of β-genus HPV-associated squamous cell carcinomas is sharply increased in immunocompromised patients; HPV-associated skin cancers are a
