Studies of human papillomaviruses (HPV) are hampered by the lack of a conventional culture system, because HPV completes its life cycle only in fully differentiated human tissue. To overcome this obstacle, the athymic mouse xenograft system has been used to study the pathogenesis of a limited number of HPV types. We recently reported the propagation of a novel HPV type in the mouse xenograft system and the cloning of its genome. Consensus primer PCR had previously identified this virus as MM7, LVX82, or PAP291. Here we report the nucleotide sequence of the 8104-bp genome of this virus, now called HPV 83. HPV 83 is most closely related to HPV 61 and HPV 72, placing it in the papillomavirus genome homology group A3. Based on limited epidemiological data, the histological appearance of infected human foreskin implants, and the structure of the predicted HPV 83 E7 protein, this virus is probably of at least intermediate cancer risk. Like other papillomaviruses, HPV 83 produces an E1 /\ E4, E5 transcript, but the position of the splice acceptor differs from that of other HPVs. The presence of an E5 open reading frame in the HPV 83 genome is uncertain; the most likely candidate to be the HPV 83 E5 protein has some structural similarity to the bovine papillomavirus 1 E5 oncoprotein, and is unlike most other HPV E5 proteins. HPV 83 is a relatively prevalent genital papillomavirus that has the largest genome of any characterized HPV and several other novel structural features that merit further study.
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