Flashcards in Human Papillomaviruses and Associated Diseases Deck (16)
What percent of cancers are associated with infection?
12-15% are viral
Structure of HPV
Non-enveloped double stranded DNA virus
Capsid protein L1: 360 molecules (72 X 5)
Capsid protein L2: ~ 72 molecules
What are the oncogenes in HPV?
E6, E7, E8: cell proliferation, transformation, immune escape
Only infects undifferentiated proliferating basal layer cells
Produced only from fully differentiated upper layer cells
Epidemiology of HPV
70-85% lifetime risk
Even bigger prevalence in developing countries
Risk factors of HPV infection
Early onset intercourse
Multiple Sex Partners
History of Genital Warts
No pap smears
What are the high-risk HPV types?
HPV16, HPV18, 31, 33, 45
What cancers can HPV cause and what percent of them is it responsible for?
Cervical cancer (100%)
Head and Neck cancer (25%)
Other anogenital cancers
Non-melanoma skin cancer?
Cytology of cervical cancer
ASCUS: atypical squamous cell of undetermined significance
LSIL: Low-grade squamous intraepithelial lesion
HSIL: High-grade squamous intraepithelial lesion
How does HPV cause cancer
High-risk HPV is frequently integrated into host chromosome
Inhibits tumor suppressors p53 and Rb (E2F also)
How does HPV testing work?
DNA detection (PCR)
Used if pap smear is abnormal
To get a better look and take biopsies of abnormal areas
Treatment for patients at high risk of cervical cancer
Surgery (Cryosurgery, Loop electrosurgical excision procedure (LEEP))
For girls and boys 11-12 years old (before sexually active)
How to make HPV vaccine
Inject HPV L1 capsid protein expressing gene into yeasts, , do mass culture, purify vaccine
By only having L1 protein, get empty virus that can make immune response without risk of infection (virus-like particle)