1. DNA Tumour Viruses Flashcards
what type of viruses cause cancer
DNA viruses
how do viruses infect cells to cause cancer?
infect non-dividing cells and forces them into cell cycle to provide machinery for viral replication
how are RNA viruses associated with cancer?
RNA viruses associated with cancer via inflammation
what is the top cancer for men? top cancer for women?
men: liver cancer
women: cervical cancer
3 characteristics of adenovirus?
- non-enveloped
- icosahedral
- 90nm diameter
3 characteristics of adenovirus genome
- dsDNA
- 35-45kb
- linear
who are at high risk for adenovirus? why
military recruits –> high stress environment + lots of exercise + tight conditions = become immunocompromised
what are 8 diseases that adenoviruses cause? what’s the most prominent one?
- acute respiratory issues
- pharyngitis
- gastroenteritis
- conjunctivitis
- pneumonia
- keratoconjunctivitis
- acute hemorrhagic cystitis
- hepatitis
upper respiratory illness is main one
describe adenovirus as a model for cancer biology
when first isolated, found it caused tumours in rodents
but we know now that injecting RODENTS with HUMAN adenovirus means the virus cannot replicate well in rodents but virus produces oncogenes to cause cancer
in humans, human adenovirus replicates very well to kill cells but we also have good immune response against it
what type of cells does adenovirus infect?
epithelial cells
what does adenovirus produce in the nucleus? what does this lead to?
creates inclusion bodies with crystal lattices of the virus in the nucleus to lead to lysis
how can we purify adenovirus?
CsCl gradient
how many proteins does adenovirus genome encode?
dsDNA genome encodes for 40 proteins
what is the role of early adenovirus genes?
sets up the cell so virus can replicate
what is the role of late adenovirus genes?
structural components, etc. for function
how long is the adenovirus life cycle?
12-14h
what did we major discovery came from adenovirus studies? how did we confirm this?
SPLICING –> mRNAs looked different than genome
hybridized viral RNA to genomic DNA and found introns looped out aka spliced out
which gene causes cancer from adenovirus? what type of gene is this?
first gene produced = E1A –> oncogene
what is the role of E1A?
transcription factor –> turns gene transcription ON
what happens if there is no E1A?
no E1A = no replication = dead virus
what are the functional domains of E1A?
- Nterminus
- CR1
- CR2
- CR3
what are the 2 roles of CR3?
- Binds TATA Box Binding Protein (TBP) which binds TATA at promoters to turn on gene expression
- Binds Activating Transcription Factor (ATF) at many promoters for genes required by adenovirus
what are the 2 types of E1A? what is the difference? how does this change the cancer outcome? what does this mean?
289R and 243R
243R does not have CR3 but can still cause cancer –> therefore not just transcription causes cancer
which functional domains of E1A are most important?
CR1, CR2, and N