Deck 37: Eukaryotic Virus Vectors

Question 1

Viruses make good gene therapy vectors because they are highly efficient at delivering nucleic acids to a particular kind of cell.

Answer 1

True

Question 2

Virus vectors that contain large transgenes do not require a helper virus to be propagated.

Answer 2

False

Question 3

RNA virus vectors do not require the same enhancer/promoter sequences as DNA virus vectors.

Answer 3

True

Question 4

In the first generation of adenovirus vectors the E3 gene was deleted.How could the virus replicate in the absence of the E3 gene products?

A)A plasmid containing the E3 gene is transfected along with the viral DNA.
B)The cell line that the recombinant viruses are grown in carries the E3 gene.
C)The E3 gene products are not required for adenovirus replication.
D)The transgene inserted into the virus complements for the E3 gene.
E)The E3 gene products are packaged into the virions.

Question 5

Which of the following is the primary reason why it is difficult to produce packaging cell lines for both retrovirus and adenovirus vectors?

A)The proteins are degraded by the proteasome in the cell.
B)It is difficult to express high levels of the proteins.
C)Many of the required viral proteins are toxic to the cell.
D)The immune system recognizes the proteins and kills the cell.
E)The proteins stimulate the RNAi defenses in the cell.

Question 6

Zinc finger nucleases could be used to solve one major disadvantage of using retrovirus vectors in gene therapy treatments.Which of the following disadvantages could they solve?

A)The low levels of transgene expression.
B)The stimulation of the immune system by the virus vector.
C)The random integration into the host genome.
D)The ability to only insert small transgenes in the vector.
E)The toxicity of the viral proteins to the transduced cell.

Question 7

A mammalian expression cassette used to produce an exogenous gene in a virus vector must have which of the following components?

A)Splicing signals.
B)Strong enhancer.
C)Polyadenylation signal
D)Translational leader sequence
E)All of the above are correct.

Question 8

Which of the following is NOT an objective for which virus vectors have been designed?

A)As anticancer agents that specifically kill tumor cells.
B)To create genetically modified animals.
C)To vaccinate animals and humans against specific diseases.
D)To produce specific proteins in cultured cells.
E)To provide functional genes in people with genetic diseases.

Question 9

What is the purpose of gene replacement therapy?

A)To change the frequency of genes in the human population.
B)To give animals useful traits.
C)To treat diseases caused by an inherited mutation.
D)To produce adult stem cells for medical treatments.
E)To produce proteins to be used as drug treatments.

Question 10

Adenoviruses that lack which of the following genes can replicate poorly in normal cells but well in many tumor cells?

A)E1A
B)E1B
C)E2
D)E3
E)E4

Question 11

Which of the following viral proteins controls the types of cells that a retrovirus can infect?

A)Capsid protein
B)Gag proteins
C)Protease
D)Envelope protein
E)Reverse transcriptase

Question 12

The EBNA-1 protein from the Epstein-Barr virus is being developed to help improve virus vectors.Which of the following describes how this protein could be used?

A)It allows a vector that contains oriP to be maintained as an episome.
B)It stimulates transcription of the transgene incorporated in the vector.
C)It inhibits the intrinsic cellular defenses against the vector.
D)It allows the cell to tolerate the toxic viral proteins.
E)It stimulates cellular DNA replication.

Question 13

Production of adeno-associated virus (AAV)vectors requires several of the proteins from adenovirus.What is the major advantage of expressing these proteins from plasmids rather than infecting the packaging cells with live adenovirus?

A)There will be no immune response against the infected cells.
B)There will be no adenovirus particles in the AAV virus preparations.
C)There will be no release of interferon from the infected cells.
D)The packaging cells will not become transformed.
E)The packaging cells will produce a higher amount of recombinant AAV particles.

Question 14

A recombinant adenovirus,called Gendicine,has been approved to treat cancer in China.Which of the following proteins does this virus express?

A)p53
B)pRb
C)p300
D)Cre recombinase
E)E1A

Question 15

Which of the following is a major disadvantage of using a vector based on adeno-associated virus (AAV)rather than an adenovirus or a retrovirus?

A)The DNA of the AAV vectors integrates into specific location in the genome.
B)The virus is toxic to human cells.
C)It infects cells of the immune system,causing a strong immune response.
D)The immune system reacts very strongly to the AAV proteins.
E)The small genome can only tolerate an insert of 4.5kb.

Question 16

SV40 was the first virus used to express a foreign protein in a cultured cell.But SV40 has which of the following limitations?

A)The small genome can only accommodate a small gene.
B)It can only infect monkey cells.
C)It does not integrate its genome into the host cell genome.
D)It replicates very slowly.
E)It does not have a strong promoter/enhancer for gene expression.

Question 17

Which of the following viruses has been used to produce the best characterized and mostly commonly used virus vectors?

A)Lentivirus
B)Herpes simplex virus
C)Adeno-associated virus
D)Adenovirus
E)Retrovirus

Question 18

Which of the following viruses has been used to express large proteins in cultured cells?

A)Adenovirus.
B)Baculovirus
C)Herpes simplex virus
D)Both adenovirus and baculovirus
E)Both adenovirus and herpes simplex virus

Question 19

Which of the following describes the primary benefit of the third generation adenovirus vectors that lack all of the viral genes?

A)They can not replicate and kill the cell.
B)They do not produce any toxic viral gene products.
C)They have more room for a large transgene.
D)They do not stimulate an immune response to the virus.
E)All of the above are correct.

Question 20

Which of the following can be used to express a second transgene from a single mRNA?

A)Downstream AUG.
B)IRES
C)Alternative mRNA splicing signals.
D)RNA editing sequences
E)All of the above.

Question 21

Retrovirus vectors have been used to treat children who have the genetic disease severe combined immunodeficiency,which results from a mutated T cell receptor gene.What is the advantage of using a retrovirus vector over an adenovirus vector in this situation? Some of the children got T leukemia years after their treatment.How did the treatment cause their cancer?

Question 22

The genes to treat most of the severe genetic diseases could fit in the AAV genome.

Question 23

Since vectors based on lentiviruses can infect nondividing cells,they have an advantage over vectors based on the genomes of other retroviruses.

Question 24

Describe two advantages that the third generation adenoviral vectors have over the original first-generation vectors.Explain the methods used to produce a recombinant adenovirus using these third generation vectors.

Question 25

The plasmids that are used to express the retroviral proteins in the packaging cell lines contain the packaging signal ( $\Psi$ ).

Question 26

Adeno-associated virus can infect dividing as well as nondividing cells.