Papillomaviruses Lecture Notes

Flashcards of key vocabulary terms and definitions from the Papillomaviruses lecture.

Human Papillomavirus (HPV)

More than 200 strains. Cause common warts, verrucas, or genital warts. High-risk strains are associated with specific types of cancer.

Virion structure

dsDNA, Baltimore Group 1; Icosahedral (T=7), non-enveloped; 60 nm diameter, composed of 72 pentamers; 360 copies of major capsid protein L1; 76 copies of minor capsid protein L2.

E1

Origin binding helicase.

E2

DNA binding protein; E1 helicase loader; tethers viral genomes to host chromosomes; transcriptional regulator.

L1

Major capsid protein, 360 per virion.

L2

Minor capsid protein, escorts genome through the endocytic pathways into the nucleus; packages the viral DNA in the capsid.

E6

Immune evasion; degrades p53 and PDZ binding proteins; upregulates telomerase.

E7

Immune evasion; degrades pRb family members; epigenetic modulator.

E5

Only encoded by alpha-HPVs; promotes cell growth; immune evasion.

Integration of HPV genome

On rare occasions the HR-HPV genome may randomly insert into the host chromosome. Only part of genome is inserted – if it contains E6/E7 coding region in absence of E2 this can lead to neoplasia.

Cervical disease: pathology

Cervical cancer is preceded by cervical disease, which has 3 stages termed ‘cervical intraepithelial neoplasia’ (CIN) or squamous intraepithelial lesion (SIN).

Transmission of HPV

HPV is primarily transmitted through direct skin-to-skin contact, often during sexual intercourse.

HPV vaccine

There are vaccines available that protect against certain high-risk and low-risk strains of HPV, significantly reducing the risk of cervical cancer.

CIN stages

Cervical intraepithelial neoplasia (CIN) is categorized into three stages: CIN 1 (mild dysplasia), CIN 2 (moderate dysplasia), and CIN 3 (severe dysplasia or carcinoma in situ).

HPV-related cancers

In addition to cervical cancer, HPV is associated with cancers of the oropharynx, anus, vulva, vagina, and penis.

Role of E2 in HPV

E2 protein plays a crucial role in regulating the transcription of viral genes and ensuring proper viral replication