Question
Explain the process of gene therapy using viral vectors.
▶️Answer/Explanation
Process of gene therapy:
- Gene therapy treats genetic diseases caused by faulty or missing genes.
- Scientists modify a virus to make it safe by removing harmful parts of its genome.
- The healthy gene is inserted into the virus, creating a viral vector.
- A common viral vector is a retrovirus, which carries RNA instead of DNA.
- When the retrovirus infects a cell, its RNA is converted into DNA by reverse transcriptase.
- This DNA is permanently inserted into the host cell’s genome, allowing the cell to make the correct protein.
- Sometimes, adenoviruses carrying DNA are used; their DNA does not integrate into the genome, so treatment may need repeating.
- Gene therapy can target body cells (somatic) or sex cells (germline).
- Example: Gendicine is an adenovirus-based gene therapy for treating head and neck cancer.
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a. used on genetic diseases caused by defective genes/lack of enzyme/ protein
b. viral vector (genetically) modified for (safe) use
c. virus genome is altered and missing gene/allele is introduced into virus
d. a retrovirus is used to introduce RNA and reverse transcriptase in a host cell
e. RNA is copied into DNA and introduced (permanently) into the cells genome
f. could use adenovirus/virus with DNA to introduce genetic material
g. in this technique DNA is not attached to cell genome
h. thus not replicated during host cell replication / treatment has to be repeated
i. it could be done in somatic treatment (body cells) or in sex cells (egg cells)
j. example (ie Gendicine, is an adenovirus used for treatment of head and neck cancer)