Biology of human papillomaviruses.

Human papillomaviruses (HPVs) cause squamous cancers of epithelial surfaces, of which genital cancers are the most common. In this article we have attempted to describe the properties and functions of the viral proteins of HPV type 16, a common cause of genital cancers, and have tried to suggest how their expression may lead to a dysregulated cell which may become malignant. These viruses are attempting to replicate in terminally differentiating keratinocytes and must stimulate G1 to S-phase progression for the replication of their genome. As part of the successful completion of replication and assembly of infectious virus particles, the virus needs at least partial differentiation to occur. Therefore, at the same time as differentiation is occurring, the nuclei of infected cells are in S-phase. While the mechanisms of action of the viral proteins are not completely understood, researchers are making progress and this article strives to bring together the conclusions from some of this work.