Viruses and Cancer

Question 1

What does the retroviral genome consist of?

Answer 1

2 RNA molecules of around 10,000 bases with polyA tails

RNase H enzyme = reverse transcriptase enzyme

Question 2

What does Gag encode?

Answer 2

A viral capsid protein-protease polyprotein (the protease cleaves itself out)

Question 3

Viruses encode cancers

Answer 3

Viruses that encode cancers have additional genes
eg) Rous sarcoma virus has Src
Src gene encodes a protein-tyrosine kinase
V-src gene is a viral version of a host proton-oncogene c-src

Question 4

How can proto oncogenes be converted to a cancer causing gene?

Answer 4

Mutation or Overexpression
V-Src is overexpressed (constitutively expressed-lacks site for inhibitory phosphorylation)
v-erbB for avian erythroblastosis (encodes EGF receptor)

Question 5

What is the inhibitor for Src?
EGF
Src causes cell proliferation

Answer 5

Dasatinib

Targets src activity and can treat various cancers in humans by down-regulating src activity

Question 6

Avian Leukosis Virus (ALV)

Answer 6

ALV replicated B cells and can cause B cell lymphomas
ALV does not carry an oncogene yet in lymphomas it is often integrated adjacent to the c-myc gene causing c-myc overexpression
c-myc over expression by ALV insertion causes increased cell proliferation

Question 7

Type of DNA!!! virus that can induce tumours in rabbits?

Answer 7

Shope Papillomavirus

Question 8

Epstein-Barr Virus is a member of what family?

Answer 8

Herpesvirus family
replicates in epithelial cells in your mouth
EBV causes glandular fever-kissing diease
In the lymph nodes EBV infects B cells and this gives rise to B cell lymphoma (can also cause DNA damage in the lymph nodes)

INDUCES CHROMOSOMAL TRANSLOCATIONS

Question 9

What two chromosomes does the EBV translocate?

Answer 9

ch14 IgH locus

ch8 myc

Question 10

What type of vaccine is GARDASIL?

Answer 10

a quadrivalent vaccine which has HPV 16, 18, 6 and 11 L1 VLPs
Protection against some cervical cancers and genital warts

Another bivalent vaccine 16/18 protects against cervical cancer

E6 and E7 can be integrated into the hosts genome and they transform the normal cell into a cancer cell.

Question 11

E7 protein -papillomavirus

Answer 11

E7 binds to pRb suppressor protein
Rb gene is mutated in familial retinoblastoma
it is a tumour suppressor gene
Binds with E2F

Question 12

E6 protein -papillomavirus

Answer 12

E6 binds to p53 TSP

p53 is mutated in 50% of all tumours