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ID: 252650 • Letter: C
Question
c, . LL. 1-1 Normal !! No Spac., Heading 1 Title Subtitle Subtie Em.... Emphas Paragraph Styles patient number is so small. This isn't a very common disease, so it would be hard to find patients that have it to begin with. There is also the fact that stem cell research and even gene therapy can be controversial. People also have a hard time with being a "guinea pig" when it comes to something as drastic as what they had to do for these patients In the news and views they mentioned how having the viral agent put the LAMB3 in the cell is random so you don't know if it could lead to mutations that cause cancer (which they pretty much disproved), so people could be weary of trying it. 8. According to the paper's authors, what was a limitation of the previous study? The first patient only had a very small amount of area treated so that therapy is unsuitable for a patient that needs a lot more healthy skins. 9. What was the nature of the mutation in the current patient? He had a homozygous acceptor splice site mutation (C1977. ?GA. Ivs i4-1G>A) within intron 14 of LAMBS 10. Why would a mutation in an intron affect the final protein? Since it was a mutation of the splice site that means the intron could be left in and that would lead to an abnormal protein. 11. TBSA is the abbreviation for Total body surface area 12. What was the original source of the cells for the transplant? They took a piece of healthy (ponblistered) skin from the patient. 13. They used a vinus to introduce what gene into these cells? An unmuted LAMB3 gene (Extra credit) They used a viral systern that could enter the cell only one time, and cause the DNA it carried to be into the host DNA. But the modified virus cannot make new infectious virus. Why do they need a modified vius that can only enter a cell once? 15. For the first grafts, they grew cells in two different ways. For one condition, they grew cells on plastic, rermoved the plastic, put the cells on gauze, then applied the cells+ gauze to the patients dermis, For the second condition, they grew the skin cells on fibrin, which was placed directly on the dermis and degraded over time. What is fbrin? 16. Why did they do the first grafts with plastic or fibrin? 17. Why did they switch to fibrin only? 18. They looked at mRNA in the restored skin for what gene(s)? 19. They looked at protein distribution (using immunofluorescence) in the restored skin for what protein(s)? 20. Do the authors this this technique would be useful for other patients? Why or why not? 21. In class and in our textbook, we discussed a related disease, epidermolysis bullosa simplex What gene(s) are mutated in this disease? 22. (Extra credit) Why do JEB and EBS share symptoms?
Explanation / Answer
In viral based gene therapy, the virus is genetically modified so that it cannot make new infectious virus. The virus genome that is responsible for making new infectious virus particles will be removed and a therapeutic gene will be added in the virus genome. The virus DNA gets integrated into the host (human) cell genome after the host is injected with the engineered virus particles. The virus infected cell will now be able to produce the protein or enzyme that the host cell lacks. It is essential for the therapeutic gene containing viral genome to remain integrated in the host genome inorder to produce the protein or enzyme that the host cell is incapable of producing. If the genes for viral replication and new virus particle assembly are retained in the virus, the viral genome gets excised from the host genome and hence the enzyme or protein will no longer be produced in the host cell.
In conclusion, the modified virus can enter the host cell only once as the genes responsible for new virus particle formation will be removed from the virus genome during engineering of the virus with therapeutic gene. As a result the virus remains integrated in the host genome and this results in the continuous production of the protein or enzyme that the host cell is incapable of synthesizing.
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