Extracellular events impacting human papillomavirus infections: Epithelial wounding to cell signaling involved in virus entry

Human papillomaviruses (HPVs), like all PVs, predominantly cause benign tumors, or warts, in stratifying squamous epithelial tissues. Virions are released from apical surfaces of the skin and mucosa and, to initiate a new infection, must utilize a break in the epithelial barrier to access mitotically active basal epithelial cells. Laboratory models currently used to study the HPV infectious process reveal that heparan sulfate proteoglycans and cellular enzymes are utilized to prime virions and activate cell signaling to coordinate virus association with a receptor complex for uptake into keratinocytes. Conventional cell-based infection systems lack many aspects relevant to determining the role of epithelial wounding in HPV infections. Nevertheless, many cellular factors involved in virion interaction with cells have been shown to actively coordinate their activities in the dynamic state of an epithelial wound. In this review, I summarize the current knowledge regarding how HPVs interact with extracellular components to prime virus particles for eventual disassembly and effectuate association with the viral receptor complex. Additionally, I propose a model to account for how epithelial injury and the wound response may actively participate in successful HPV infection of basal epithelial cells.