Flashcards in L67 Deck (23):
What is the genome and viral structure of polyomavirus & HPV?
- Nuclear replication
Naked + icosahedral
What is the presentation of polyoma virus?
Only seen in IC pts
Polyoma virus transmission
1ary inoculation of lungs
2ary inoculation of trophic organs
What is the reading frame of polyoma virus vs HPV?
Polyoma = open reading frame on BOTH strands
- Coded in counter vs clockwise fashion accordingly
HPV = reading frame on 1 strand only, therefore coded directionally
How is polyoma virus released from host cells?
What are the 3 major parts of the polyoma virus genome?
Early = non-structural
- Large T antigen, inactivates p53 & Rb
Late = structural
What is the polyoma virus that infects the CNS? What disease does it cause?
- Infects oligiodendrocytes
- Demyelinating, white matter
- "Non-enhancing brain lesions"
- Gait, vision, speech changes
What is the polyoma virus that infects the kidneys? What diseases does it cause?
Hemorrhagic cystitis (more common in stem cell transplant pts)
How is HPV transmitted?
Direct contact of warts - hand to hand or sexual contact
What are the 3 major regions of the HPV genome?
Early = E1-7
- Cancer proteins
Late = structural proteins
- L1 = major capsid
- L2 = minor capsid
What are 2 unique features about HPV?
1. Can cause cancer
2. Associated with cells at specific stages of differentiation - actively dividing cells
Explain HPV pathogenesis.
HPV + basal layer epithelium
Codes early genes = host cell growth --> wart
Replicate viral episome with HOST DNApol
Late genes on in terminally differentiated epithelial layers (top, keratinized)
Virus assembles in nucleus - sheds with dead upper layers
What event increases the likelihood of a carcinogenic strain of HPV?
Integration of HPV episome into host cell DNA
- Lose E2
- More direct upregulation of E6&7
Describe how HPV can cause cancer.
@ transition zones
- E6: decreased p53
- E7: degrade Rb
Net: loss of regulation of cell cycle, neoplasia
What types of cancer does HPV cause?
Anal - increased in HIV+ gay men
What disease does HPV cause if newborns get it from the birth canal?
Recurrent respiratory papillomatosis
Which strains of HPV are low risk?
6 & 11
Which strains of HPV are high risk?
16 & 18
What is CIN 1?
Cervical intra-epithelial neoplasia
Overgrowth due to 6 & 11
Lesions that are NOT considered cancer precursor
What types of CIN are considered pre-cancerous lesions?
CIN 2 & 3
What characteristic of an HPV infection is a good predictor of a carcinogenic strain?
Persistence = 2+ infections of the same strain in 6-12mo
Gold standard of detecting HPV
Molecular DNA/RNA detection