A HUMAN-PAPILLOMAVIRUS RELATED TO HUMAN-PAPILLOMAVIRUS MM7 LVX82 PRODUCES DISTINCT HISTOLOGICAL ABNORMALITIES IN HUMAN FORESKIN IMPLANTS GROWN AS ATHYMIC MOUSE XENOGRAFTS/

Studies of human papillomaviruses (HPVs) 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 HPV 11 and to develop neutralizing assays for vaccine development. Recently, HPV 40 has been produced in this system, and HPV 16 has bee n produced using mice with severe combined immune deficiency. To ident ify and characterize additional genital HPV types for similar studies, condylomata acuminata lesions containing a high copy number of HPV an d detectable L1 major capsid protein were used to prepare infectious v irus stocks. Human foreskin fragments were infected with the virus pre parations and implanted under the renal capsules of athymic mice. Afte r 5 months of growth, implant tissue was removed and processed for stu dies to detect HPV infection. Evidence of HPV infection was noted in s ome of the implants, but in contrast to HPV ii-infected epithelium, th e implants derived from the new virus preparations contained a lesser degree of acanthosis, less developed koilocytosis, and a reduced numbe r of preserved nuclei in the hyperkeratotic material within the cyst l ining. The L1 consensus region was amplified by polymerase chain react ion from implant DNA and sequenced. Alignment of the amplified sequenc es with those in the HPV sequence database showed that the 452-bp ampl imer was closely related but not identical to HPV LVX82 and HPV MM7 (a lso called Pap 291). The entire 7.9-kb genome was amplified by polymer ase chain reaction and cloned. The presence of virions of the new isol ate (named HPV IU) in the implants was verified by immunohistochemical detection of L1 major capsid protein and by demonstration of virion p articles by electron microscopy. A second extract was made from one of the new implants and used to successfully propagate HPV IU. These exp eriments demonstrate that experimental infection of human epithelium w ith the new isolate, HPV IU, is associated with histological abnormali ties that differ in potentially important ways from the changes observ ed in experimental HPV 11 infection. (C) 1998 Academic Press.