(a)[3]
A gene therapy trial for cystic fibrosis used a viral vector. The viral vector triggered a primary immune response and the formation of memory cells. Explain why the formation of memory cells stops the gene therapy from being effective in long-term chronic conditions such as cystic fibrosis.
(b)[4]
With reference to the three types of vectors commonly used, discuss the difficulties involved in selecting suitable vectors for gene therapy. Do not include problems linked to an immune response in your answer.
(c(i))[2]
Explain why the immune system tolerated the vectors well.
(c(ii))[1]
Suggest why it is impossible to produce genetically engineered red blood cells except by using genetically engineered stem cells.