Table 1.

Human papillomavirus (HPV) genome and viral proteins.

Genome regions	Viral protein	Function
URRa/LCRb		Origin of viral replication; site for viral and cellular transcription factors
Late ORFsc	L1	Constituent of viral capsid
	L2	Constituent of viral capsid; DNA encapsidation and virus entry and transit in the nucleus
Early ORFsc	E1	Replication and amplification of the viral genome in the nucleus of infected cells
	E2	Regulates the viral cycle and transcription factor for proteins E6 and E7
	E4	Binds to cytokeratins, contributes to virus release and transmission
	E5	Plays a role in evading the immune response and apoptosisd
	E6	Amplification of the viral genome and carcinogenesise
	E7	Amplification of the viral genome and carcinogenesise

^aUpstream regulatory region.

^bLong control region.

^cOpen read frames.

^dPresent in the alpha genus.

^eFunction in some types of HPV.

Source: Prepared by the authors based on references (Egawa et al., 2015⁷ and Van Doorslaer et al., 2018²¹).