Propagation of human papillomavirus type 59 in the athymic mouse xenograft system

Studies of human papillomavirus (HPV) infection are hampered by the lack of an adequate culture system. The athymic mouse xenograft system permits propagation of HPV, but only a few HPV types have been grown in this manner. To produce an oncogenic type for studies of HPV pathogenesis, a condylomata acuminata lesion from an immunosuppressed patient was used to prepare an infectious extract. The patient's lesion was shown by PCR analysis to contain abundant HPV 59 (an oncogenic type) and a lesser amount of HPV 11, a nononcogenic type. The extract was used to infect human foreskin tissue which was subsequently implanted into athymic mice. Characterization of implants recovered after 3-4 months of growth revealed the presence of HPV 59 exclusively. A second extract was prepared from one of these implants and used in an additional experiment to demonstrate the passage of HPV 59. Compared to the histopathologic changes induced by the prototypic nononcogenic HPV 11, infection with HPV 59 caused a higher degree of basal cell crowding, less acanthosis, minimal papillomatosis and less pronounced koilocytosis.