Human papillomavirus DNA replication

Abstract

Human papillomaviruses (HPV) are a family of double-stranded circular DNA viruses with a genomic size of around eight kilobases. HPV are highly species–specific and infect only stratified squamous epithelial cells or mucosal membranes. Similar to many other aspects of HPV molecular biology, the DNA replication of bovine papillomavirus type 1 (BPV) has been the most studied and has become the paradigm for HPV–DNA replication. DNA replication studies with various HPVs have shown that although the BPV paradigm is often accurate, differences do exist between the viral DNA replication of BPV and some HPVs. Viruses infect at the basal layer of epidermal tissue and the virus undergoes three stages of replication. Within the basal and first suprabasal epidermal layers, the viral DNA is propagated until there are 50–100 copies per cell. During the second stage, the maintenance stage, viral DNA replication is replicated in synchrony with the host cell cycle, only occurring during S phase of the host cell cycle. During both of these stages the HPV DNA is maintained as episomal plasmids in the nuclei of infected cells. The third and final stage is the vegetative stage of viral replication. The vegetative stage only occurs in terminally differentiated tissues, and includes both an increase in the number of viral genome copies, as well as the expression of late genes and assembly of new virus.. The chapter also discusses E1 protein binding sequence (E1BS), E2 protein family, HPV–DNA replication in terminally differentiated cells, and so on.