Oncogenic Viruses

Question 1

Which DNA virus was identified in Burkitt’s lymphoma?

Answer 1

Epstein-Barr Virus (HHV4)

Question 2

Name the two main HHV4 viral proteins that are implicated in immortalization and describe their function.

Answer 2

EBNA3C overcomes the Rb cell cycle checkpoint and LMP1 continuously stimulates CD40 which increases bcl-2 to encourage cell proliferation and discourages apoptosis

Question 3

Which DNA virus was identified in Kaposi sarcoma?

Answer 3

KSHV aka HHV8

Question 4

Which groups experience an elevated risk of developing cancer from HHV8 infection?

Answer 4

Immunosuppressed individuals such as AIDS patients and transplant patients

Question 5

Name some ways that KSHV/HHV8 interfere with p53 activity

Answer 5

secrete vIL6 which inhibits the apoptotic pathways and up-regulates Bcl-2 which promotes cell survival.

Question 6

Name some ways that KSHV/HHV8 interfere with Rb activity

Answer 6

viral cyclin phosphorylates Rb rendering it inactive AND virus contain c-myc which is a proto-oncogene that encourages progression of the cell cycle

Question 7

Which DNA virus is associated with hepadnaviral oncogenesis (HBV) and development of heptocellular carcinoma (HCC)?

Answer 7

Hepatitis B

Question 8

Hepatitis B targets which organ in the body?

Answer 8

The liver is the major site of viral replication. This causes a lot of inflammation which results in liver damage.

Question 9

What is the name of the viral oncoprotein in hepatitis B? What does it do?

Answer 9

HB X protein activates src tryosine kinase and inhibits p53 function.

Question 10

How is hepatitis B transmitted?

Answer 10

sex, needles, blood transfusions, mother-to-fetus

Question 11

In what way is hepatitis B similar to AIDS?

Answer 11

Hepatitis B behaves like a retrovirus by using a reverse transcriptase to form DNA from RNA

Question 12

What are two pathways that HBV and HCV cause cell transformation?

Answer 12

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.

Question 13

What is a benefit of possessing a reverse transcriptase?

Answer 13

Can make DNA from RNA in the cytoplasm

Question 14

What is the benefit of possessing an RNA dependent RNA polymerase? *Seen in HCV

Answer 14

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

Question 15

Which cancer(s) is/are associated with human papilloma virus (HPV)? Which types?

Answer 15

HPV 16/18 –> cervical cancer in women
Oral cancer in males
Others: anal, vulvar, vaginal, penile, pharynx

Question 16

What is the name of the vaccine created to protect against HPV?

Answer 16

Gardasil (93-100% effective)

Question 17

How many early genes and how many late genes does HPV 16 have?

Answer 17

7 early genes and 2 late genes

Question 18

When are early (E) viral genes expressed? What do they code for?

Answer 18

Early viral genes are expressed before the synthesis phase and they code for regulatory proteins

Question 19

When are late (L) viral genes expressed? What do they code for?

Answer 19

Late viral genes are expressed after the synthesis phase. They code for capsid proteins that are responsible for viral assembly. (L1 and L2)

Question 20

Why does HPV remain in the S phase for so long?

Answer 20

So that it can amplify the virus as much as possible

Question 21

When discussing HPV, in which layer of the stratified squamous epithelium does S phase occur?

Answer 21

stratum basale

Question 22

When discussing HPV, in which layer of the stratified squamous epithelium does shedding of the viral particles occur?

Answer 22

stratified corneum

Question 23

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?

Answer 23

E6 and E7

L1 and L2

Question 24

In HPV, when is E6 and E7 expressed?

Answer 24

After the virus is integrated into the genome, before synthesis.

Question 25

Which HPV protein can mimic the PDGF ligand and therefore act as a continuously “on” receptor?

Answer 25

E5