Tbr Bio Diagnostic Set 2 passage 5 question 30

[javksmith93]

Tbr bio question

Which of the following must be true in order for the technique described in experiment 1 to be effective when used on humans

A) The Adenovirus used must possess the genes necessary to replicate itself
B)the Adenovirus used must lack the genes necessary to replicate itself
C) The CFTR DNA packaged into the virus should encode a non-functional protein
D) The CFTR DNA packaged into the virus should lack exons.

Expirement 1
DNA encoding a functional human CFTR gene was packaged into an adenovirus the virus was then allowed to infect the lungs of a rats injecting its DNA into lung epithelial cells the RNA hybridization experiments were then performed showing that the injected cells now secred CL in response to CMP stimulus while uninjected cells did not.

I thought the correct response should be A but TBR says it is B sense if the virus could replicate it would cause the cell to under go lysis and destroy it. My problem is that if the virus doesn't replicate you would not be able to infect that many cells and I was under the impression that gene therapies usually use replicating viruses so that the gene therapy product can continue to reproduce?

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[RH8448]

This is how I could make sense of this. Someone can elaborate or correct me if I'm wrong.

You do not want your virus that carries the desired information to lyse. This would be a virus in the lysogenic phase and would be pathogenic. We want a non pathogenic virus to "deliver" the gene into the DNA. Once it is incorporated into the DNA it is permanent and will continually be transcribed as long as that region is active. So an infection of the virus would make its way into the local cells and permanently alter the DNA. Genes that make the virus pathogenic by lysing the cell would be too virulent.

So, the desired virus for gene therapy would be one that would infect the cells by incorporating into the DNA allowing for transcription of the desired gene. We don't want it to produce so much of its self that it "hijacks" the cell. In other words we want a virus that has lytic properties.

 

[javksmith93]

This is how I could make sense of this. Someone can elaborate or correct me if I'm wrong.

You do not want your virus that carries the desired information to lyse. This would be a virus in the lysogenic phase and would be pathogenic. We want a non pathogenic virus to "deliver" the gene into the DNA. Once it is incorporated into the DNA it is permanent and will continually be transcribed as long as that region is active. So an infection of the virus would make its way into the local cells and permanently alter the DNA. Genes that make the virus pathogenic by lysing the cell would be too virulent.

So, the desired virus for gene therapy would be one that would infect the cells by incorporating into the DNA allowing for transcription of the desired gene. We don't want it to produce so much of its self that it "hijacks" the cell. In other words we want a virus that has lytic properties.

that makes sense thank you.