Transforming Properties of Beta-3 Human Papillomavirus E6 and E7 Proteins.

The beta human papillomaviruses (HPVs) are subdivided into 5 species (beta-1 to beta-5), and they were first identified in the skin. However, the beta-3 species appears to be more highly represented in the mucosal epithelia than in the skin. Functional studies have also highlighted that beta-3 HPV49 shares some functional similarities with mucosal high-risk (HR) HPV16. Here, we describe the characterization of the in vitro transforming properties of the entire beta-3 species, which includes three additional HPV types: HPV75, HPV76, and HPV115. HPV49, HPV75, and HPV76 E6 and E7 (E6/E7), but not HPV115 E6 and E7, efficiently inactivate the p53 and pRb pathways and immortalize or extend the life span of human foreskin keratinocytes (HFKs). As observed for HR HPV16, cell cycle deregulation mediated by beta-3 HPV E6/E7 expression leads to p16INK4a accumulation, whereas no p16INK4a was detected in beta-2 HPV38 E6/E7 HFKs. As shown for HPV49 E6, HPV75 and HPV76 E6s degrade p53 by an E6AP/proteasome-mediated mechanism. Comparative analysis of cellular gene expression patterns of HFKs containing E6 and E7 from HR HPV16, beta-3 HPV types, and beta-2 HPV38 further highlights the functional similarities of HR HPV16 and beta-3 HPV49, HPV75, and HPV76. The expression profiles of these four HPV HFKs show some similarities and diverge substantially from those of beta-3 HPV115 E6/E7 and beta-2 HPV38 E6/E7 HFKs. In summary, our data show that beta-3 HPV types share some mechanisms with HR HPV types and pave the way for additional studies aiming to evaluate their potential role in human pathologies.IMPORTANCE Human papillomaviruses are currently classified in different genera. Mucosal HPVs belonging to the alpha genus have been clearly associated with carcinogenesis of the mucosal epithelium at different sites. Beta HPV types have been classified as cutaneous. Although findings indicate that some beta HPVs from species 1 and 2 play a role, together with UV irradiation, in skin cancer, very little is known about the transforming properties of most of the beta HPVs. This report shows the transforming activity of E6 and E7 from beta-3 HPV types. Moreover, it highlights that beta-3 HPVs share some biological properties more extensively with mucosal high-risk HPV16 than with beta-2 HPV38. This report provides new paradigms for a better understanding of the biology of the different HPV types and their possible association with lesions at mucosal and/or cutaneous epithelia.

Prevalence and Concordance of Cutaneous Beta Human Papillomavirus Infection at Mucosal and Cutaneous Sites.

Background: Cutaneous beta human papillomavirus (HPV) infection across cutaneous and mucosal tissues within individuals has not been examined. Methods: A subcohort of men (n = 87) participating in the HPV Infection in Men (HIM) study provided eyebrow hairs, forearm skin swabs, genital skin swabs, oral rinse samples, and anal swabs. Beta-HPV DNA in the 5 tissues was detected using a multiplex assay, and site-specific beta-HPV prevalence was examined. Results: Any beta-HPV was most prevalent in genital skin (81.6%), followed by forearm skin (64.4%), eyebrow hairs (60.9%), oral mucosa (35.6%), and anal mucosa (33.3%). Most prevalent beta-HPV types included HPV-38 (beta-2) in both genital skin (32.2%) and eyebrow hairs (16.1%), HPV-12 (beta-1) in forearm skin (23%) and oral mucosa (9.2%), and HPV-76 (beta-3) in anal mucosa (14.9%). Concordance of any beta-HPV infection was greater (31.0%) across the 3 keratinized tissue sites (genital skin, eyebrow hairs, forearm skin) than across the 2 mucosal sites (anal and oral mucosa, 6.9%). Conclusions: Prevalence of beta-HPV varied by anatomic site of infection. Biological properties of beta-HPV types detected at mucosal sites and their role in disease pathogenesis should be examined.