Controls in the papillomavirus life cycle.

Papillomaviruses cause neoplasia of epithelia and subepidermal fibroblasts which may progress to certain forms of malignancies. During the viral life cycle, papillomavirus genomes receive, process and generate signals. Transcription factors binding to their enhancer carry information about tissue specificity and hormonal regulation, while other factors in the cornified layer of the epidermis activate capsid protein production. Furthermore, products of the viral E2 and E1 genes constitute feedback signals that modulate viral transcription and replication. Proteins derived from the genes E5, E6 and E7 modulate cellular homeostasis so as to induce neoplatic transformation. A molecular understanding of these regulatory events may form a prerequisite for a causal therapy of papillomavirus-induced malignancies.