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Historically, the papillomaviruses and polyomaviruses have been discussed together in microbiology textbooks, lumped under the category of papovaviruses. Papovaviruses are now split into two separate families: Papillomaviridae and Polyomaviridae. The unique characteristics that distinguish them from each other are shown in Table 19–1.
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Overview
Human papillomaviruses (HPVs), the most common sexually transmitted infections in the United States, are naked capsid, icosahedral, double-stranded circular DNA viruses that replicate in the nucleus of the infected cell by using host RNA polymerase for transcription and host DNA polymerase for genome replication. More than 100 genotypes of HPVs have been identified in human specimens. The genotypes are antigenically different, and groups of genotypes are associated with specific lesions, and low-risk or high-risk genotypes for cancers. HPVs are transmitted through skin-to-skin contact and through vaginal, anal or oral sex. HPVs have been identified in common hand warts, plantar warts, flat cutaneous warts of other skin areas (HPV 1-4, 7, 10); in juvenile laryngeal papillomas (HPV 6, 11); and in a variety of genital hyperplastic epithelial lesions, including cervical, vulvar, and penile warts and papillomas (HPV 6, 11, 16, 18). In addition, they are associated with premalignant cervical intraepithelial neoplasia (CIN) and malignant disease, cervical cancer (HPV 16, 18). Lesions comparable to those occurring in the cervix are now recognized in the anus, especially among men who have sex with men (MSM) and those who are infected by HIV. HPV 6 and 11 (low risk) are most common genotypes associated with genital infections and cause benign condylomas and condylomata acuminate, HPV 16 and 18 are considered the high-risk genotypes because of their potential to cause malignant cancers such as cervical cancer in women and oropharyngeal cancer mainly in men. While a majority of HPV-associated infections are benign and cleared by the immune system over time, some progress to malignancies. HPV can be detected on ...