Betapapillomavirus

Betapapillomavirus is a genus of papillomaviruses within the family Papillomaviridae. Betapapillomaviruses (beta-HPV) primarily infect the skin of humans and are one of several genera that cause human papillomavirus infections. More than a dozen beta types have been described, with HPV-5 and HPV-8 among the best studied; types are genetically related but type-specific.

Genome and biology: Beta-HPVs are non-enveloped icosahedral viruses with circular double-stranded DNA genomes of roughly 8 kilobases. They encode early genes E1, E2, E6, E7, sometimes E5, and late genes L1 and L2. The infection targets basal keratinocytes in the epidermis; replication occurs as infected cells differentiate, with late genes expressed in suprabasal layers. The viruses establish long-term colonization of skin and typically cause no overt disease in most individuals.

Clinical features and disease associations: Most infections are asymptomatic or result in minor cutaneous warts. In people with epidermodysplasia verruciformis (EV) or in severely immunocompromised individuals, beta-HPV infection can lead to widespread flat warts and has been linked to an increased risk of non-melanoma skin cancer, particularly when combined with ultraviolet light exposure. The precise role of beta-HPV in sporadic skin cancers remains uncertain; evidence suggests it may act as a cofactor rather than a primary cause. Serology is unreliable for diagnosis; detection relies on molecular methods such as PCR.

Diagnosis and prevention: Diagnosis is through detection and typing of HPV DNA from skin lesions. There are no licensed vaccines targeting beta-HPV types; current HPV vaccines protect against several alpha-HPV types associated with mucosal cancers and warts. Research into multivalent vaccines aims to broaden protection against cutaneous HPV types. Management of beta-HPV infections focuses on treating lesions and monitoring skin cancers in high-risk individuals.

Taxonomy: Betapapillomavirus is one genus within Papillomaviridae, comprising multiple species and numerous types. The taxonomy is under ongoing refinement.