Table 1.

Summary of human papillomavirus (HPV) open reading frames/genes and function of the viral proteins

Open reading frame/genes	Protein function
E1	Viral replication; mediates episomal DNA replication
E2	Regulates viral transcription and viral replication; regulates viral copy numbers
E4	Interacts with cytoskeletal proteins; facilitates virion release
E5	Downregulates MHC Class I molecules; stimulates cell proliferation; prevents differentiation; activates EGFR
E6	Maintains viral genome; inactivates several host‐cell proteins (e.g. inhibits apoptosis by degradation of p53, induces malignant transformation together with E7)
E7	Maintains viral genome; reactivates cellular replication mechanisms by binding pRB; induces malignant transformation together with E6
E8	Function is not totally known. A fusion protein 16‐E8∧E2 limits the viral copy number but is not required for plasmid persistence and maintenance
L1	Major viral capsid protein
L2	Minor viral capsid protein

EGFR, epidermal growth factor receptor; MHC, major histocompatibility complex; pRB, retinoblastoma tumor suppressor protein.