Oncogenic Viruses Flashcards
Which DNA virus was identified in Burkitt’s lymphoma?
Epstein-Barr Virus (HHV4)
Name the two main HHV4 viral proteins that are implicated in immortalization and describe their function.
EBNA3C overcomes the Rb cell cycle checkpoint and LMP1 continuously stimulates CD40 which increases bcl-2 to encourage cell proliferation and discourages apoptosis
Which DNA virus was identified in Kaposi sarcoma?
KSHV aka HHV8
Which groups experience an elevated risk of developing cancer from HHV8 infection?
Immunosuppressed individuals such as AIDS patients and transplant patients
Name some ways that KSHV/HHV8 interfere with p53 activity
secrete vIL6 which inhibits the apoptotic pathways and up-regulates Bcl-2 which promotes cell survival.
Name some ways that KSHV/HHV8 interfere with Rb activity
viral cyclin phosphorylates Rb rendering it inactive AND virus contain c-myc which is a proto-oncogene that encourages progression of the cell cycle
Which DNA virus is associated with hepadnaviral oncogenesis (HBV) and development of heptocellular carcinoma (HCC)?
Hepatitis B
Hepatitis B targets which organ in the body?
The liver is the major site of viral replication. This causes a lot of inflammation which results in liver damage.
What is the name of the viral oncoprotein in hepatitis B? What does it do?
HB X protein activates src tryosine kinase and inhibits p53 function.
How is hepatitis B transmitted?
sex, needles, blood transfusions, mother-to-fetus
In what way is hepatitis B similar to AIDS?
Hepatitis B behaves like a retrovirus by using a reverse transcriptase to form DNA from RNA
What are two pathways that HBV and HCV cause cell transformation?
Hepatitis B and C can employ a direct pathway that uses a spliced protein to directly transform cells and cause cancer.
It can also employ an indirect pathway that causes chronic hepatitis, cirrhosis (liver failure), AND THEN transform cells and cause cancer.
What is a benefit of possessing a reverse transcriptase?
Can make DNA from RNA in the cytoplasm
What is the benefit of possessing an RNA dependent RNA polymerase? *Seen in HCV
The RNA polymerase will produce a - RNA strand in the cytoplasm and then use that strand as a template to produce the + RNA strand which is basically the copies of the viral genome
Which cancer(s) is/are associated with human papilloma virus (HPV)? Which types?
HPV 16/18 –> cervical cancer in women
Oral cancer in males
Others: anal, vulvar, vaginal, penile, pharynx
What is the name of the vaccine created to protect against HPV?
Gardasil (93-100% effective)
How many early genes and how many late genes does HPV 16 have?
7 early genes and 2 late genes
When are early (E) viral genes expressed? What do they code for?
Early viral genes are expressed before the synthesis phase and they code for regulatory proteins
When are late (L) viral genes expressed? What do they code for?
Late viral genes are expressed after the synthesis phase. They code for capsid proteins that are responsible for viral assembly. (L1 and L2)
Why does HPV remain in the S phase for so long?
So that it can amplify the virus as much as possible
When discussing HPV, in which layer of the stratified squamous epithelium does S phase occur?
stratum basale
When discussing HPV, in which layer of the stratified squamous epithelium does shedding of the viral particles occur?
stratified corneum
When discussing HPV, which 2 early viral proteins are responsible for cell transformation (G1 –> S phase) and which 2 late viral protein are responsible for capsomere formation/ viral assembly?
E6 and E7
L1 and L2
In HPV, when is E6 and E7 expressed?
After the virus is integrated into the genome, before synthesis.