Mucosal junctions: open doors to HPV and HIV infections?

Throughout adult life, new developmental commitment of adult stem cells causes reversible epithelial replacements in various mucosal surfaces, including the uterine cervix and the anal canal. Located at the squamocolumnar junctions, these metaplastic conversions are associated with chronic inflammation and deregulated expression of soluble and cell-membrane factors important for antiviral immune response. In this paper, we propose that these histological and immunological features increase the susceptibility of these metaplastic microenvironments to human papillomavirus and human immunodeficiency virus infections. Identification of the anatomical sites and cell populations within the anogenital tract, which is the site primary infected by these viruses, is crucial for the understanding of the pathogenesis of viral disease and development of antiviral strategies.