Retrovirus Oncogenesis

Question 1

DNA viruses that cause cancer (5)

Answer 1

1. Herpes
2. Hepadna
3. Adeno
4. Papova
5. Pox

Question 2

RNA viruses that cause cancer (2)

Answer 2

1. Flavi

2. Retro

Question 3

Whats an oncogene

Answer 3

Any genetic element that causes cancer

Question 4

What is a c-oncogene

Answer 4

A cellular (host) oncogene

Involved in regulation of cell growth, division, differentiation

Activated via:

• Insertional mutagenesis
• Transposition
• Gene amplification
• Mutation

Question 5

What is a v-oncogene

Answer 5

Viral oncogene

Usually code only for exons

Under control of LTRs

Question 6

Mutations of LTRs can cause what

Answer 6

Uncontrollable amplification

Question 7

What is replication competent

Answer 7

Virus can replicate entirely by itself

Question 8

What is replication defective

Answer 8

Virus requires interaction with another virus (helper virus) to complete infectious cycle

Question 9

Are retroviruses replication competent or defective? Which cause cancer

Answer 9

Can be either - both cause cancer!

Question 10

How are replication competent viruses oncogenic?

Answer 10

Cis-activating

Provirus inserted either on c-onc (knocking it out) or near it (upstream - causing upregulation via LTR)

Question 11

How are replication defective viruses oncogeneic

Answer 11

Transducing

Question 12

Which has shorter tumor latency period (transducing or cis-activating)

Answer 12

Transducing

Question 13

Which has a higher efficacy of tumor formation (transducing or cis-activating)

Answer 13

Transducing

Question 14

Can cis-activating transform cultured cells

Answer 14

No

Question 15

What does cellular and humoral immunity do to virus

Answer 15

Cellular: clears virus

Humoral: protects against re-infection

Question 16

List some ways the immune system can enhance viral damage

Answer 16

1. Increased secondary response to killer T-cells
2. ADCC or complement mediated cell lysis
3. Binding virus-Ab complexes to Fc receptors —> more cells involved
4. Immune complex depositions in eye, brain, etc

Question 17

IgG is dominant maternal antibody in

Answer 17

Cows, horses

Question 18

IgA is dominant maternal antibody in

Answer 18

Dogs, pigs

Question 19

What is translocation cutoff time

Answer 19

Time to absorb maternal antibodies (usually around 2 days)

Question 20

List reasons failure of antibody transfer

Answer 20

1. Premature/weak
2. Delay to suckle
3. Death of dam
4. Low colostrum
   etc etc

Question 21

What is most common immunodeficinecy disease in domestic animals

Answer 21

Failure of transfer

Question 22

Why is vaccinating too early dangerous

Answer 22

Neonate may have maternal antibodies that attack vaccine, reducing titer

Question 23

Why are boosters important

Answer 23

If you vaccinated too early, boosters will boost immune response to titer

Question 24

Why is vaccinating too late dangerous

Answer 24

Maternal antibodies will drop below protective levels and animal will be susceptible to infection

Question 25

What is window of susceptibility

Answer 25

Maternal antibody level that kills vaccine is below the minumum level needed for protection! When you vaccinate in this window, animal is not protected adequately