Papillomaviridae

Characteristics of Papillomavirus

Unenveloped icosahedral virions (t=7)
DNA Genome
- Circular
- Genome replication is catalyzed by host DNA polymerases
VERY host specific; cross species transmission is rare
VERY difficult to grow in laboratory; replication only occurs in terminally differentiating epithelial cells

Warts

Keratinized skin tumors or proliferative squamous cell lesions on mucosal surfaces
Warts spread by direct contact
Warts are usually benign

Genome Expression

Have a single stranded regulatory region URR
Mrna are transcribed by host RNA pol II
Happens before DNA replication
The first products are E1 (nuclear phosphoprotein) and E2
E1 is required binds to viral DNA replication origin ( do not need DNA polymerase) ○
E2 (regulates viral transcription and is also required)
E5: activates cell proliferation ○
E6: bind p53 ( leads to death) but removing p53 can lead to tumor
E7: bind to Rb prevents phosphorylation ○
In HPV infected cell Rb binds to E7 causing Rb to continue proliferation
In normal cel Rb binds directly to E2F to stop proliferation

Disease:

Virology Exam 3