Human papillomavirus, or HPV, is a very common group of viruses that can infect epithelial cells, like those on your skin and the lining of your mouth, throat, and genitals. There are over 200 known HPV types, and some can cause health problems ranging from warts to certain cancers.
Over 200 human papillomavirus (HPV) strains exist, around 40 types fall into the low risk category and around 12 types are considered high-risk, with HPV 16 and 18 being the most prevalent.
HPV encodes several proteins with critical roles in their life cycle and interactions with host cells.
Early Proteins (Expressed during viral genome replication):
E1 and E2: Play a key role in viral DNA replication and regulate the switch between early and late gene expression.
E5: Helps the virus evade the immune system and promotes cell proliferation.
E6 and E7: These are the main oncoproteins of high-risk HPV types. They disrupt cell cycle control and promote cancerous growth by interacting with host cell proteins like p53 and Rb.
E4 (sometimes classified as Late): May contribute to late viral functions and interactions with the host immune system.
Late Proteins (Expressed during capsid formation):
L1 and L2: These form the viral capsid, the protein shell that protects the viral genome. L1 is the major capsid protein and the main component of HPV vaccines.