Production of infectious human papillomavirus independently of viral replication and epithelial cell differentiation

Papillomaviruses are small DNA viruses that are associated with benign and malignant epithelial lesions, including >95% of cervical cancers and approximately 20% of head and neck cancers. Because papillomavirus replication and virion production are tied to epithelial cell differentiation, infectious papillomavirus virion production has been limited to cumbersome organotypic cultures and mouse xenografts. Consequent difficulties in obtaining useful amounts of wild-type or mutant human papillomavirus (HPV) virions have greatly limited studies on many aspects of papillomavirus biology. To overcome these limitations, we developed a system to encapsidate the full-length papillomaviral genome into infectious virions, independently of viral DNA replication and epithelial differentiation. This transient-transfection-based system produces >1,000 times more infectious virus per cell culture dish than the much more labor-intensive organotypic culture. Furthermore, we show that this method allows the facile generation of infectious particles containing wild-type, mutant, or chimeric papillomaviral genomes, overcoming barriers to studying many facets of replication, host interactions, and vaccine and drug development, which has been limited by the insufficient availability of infectious virions.