HPV-Based Screening, Triage, Treatment, and Followup Strategies in the Management of Cervical Intraepithelial Neoplasia

Table 1

Major functions of HPV proteins.

HPV proteins	Functions	Reference
E1	Involved in productive HPV replication.	[9]
E2	Regulates transcription from different HPV promoters.	[13]
E3	Recently identified gene located in early gene region and found only in a few papillomavirus types (HPV1, 11, 16, 31, 33); its function has not been identified.	[24]
E4	Represent up to 30% of total wart protein produce by HPV-1a and might serve as scaffold, transport, or structural protein.	[14]
E5	Inactivates with cellular host proteins (MHC I, Bap31); these interactions are important for the biological activity of the protein in cell transformation and evasion of the immune response.; Play a role in regulation of transduction pathways through up-regulation of phosphatidylinositol-3′-kinase.	[16, 17, 19]
E6	Inactivates the tumor suppressor protein p53, involved in the control of cell proliferation and cell response to genotoxic stress and in DNA damage.	[20]
E7	Interacts with the pRb tumor suppressor protein. These interactions influence the gene expression involved in progression to S-phase of the cell cycle, such as cyclin A, cyclin D, and cyclin E genes.	[20, 22]
E8	Recently identified gene located in early gene region and found only in a few papillomavirus types (HPV 1, 11, 16, 31, 33). A fusion protein, E8^∧E2C, functions as a negative regulator for HPV DNA replication playing a role in the control of viral copy number as well as in the stable maintenance of HPV episomes.	[24]
L1; L2	Major capsid protein.; Minor capsid protein.	[26]