MMT: gene therapy Flashcards
What is ex vivo delivery?
Gene is delivered to cells outside the body then returned.
What is in situ delivery?
Gene is delivered directly at the site, like a gene injected into a tumor.
What is in vivo delivery?
Gene delivered into the body but not directly into the site, like via IV.
What are advantages of using adenovirus as a vector?
They enter cells effectively.
What is a disadvantage of using adenovirus as a vector?
Activates a strong immune response and produced DNA that sits in the cytosol and doesn’t pass to daughter cells.
What are advantages of using AAV as a vector?
They produce less immune response.
What are disadvantages of using AAV as a vector?
Can only use small proteins and production can be complicated.
What are advantages of using retroviruses as vectors?
Their material can be passed to daughter cells.
What are disadvantages of using retroviruses as a vector?
Random integration (may disrupt normal genome) and can only target dividing cells.
What are advantages of HSV as a vector?
It can code for big proteins.
What are disadvantages of using HSV as a vector?
Potential cytotoxicity/lysing.
Describe how non-integrating viruses function.
- Virus with therapeutic DNA inside is injected and attaches to a cell.
- Virus enters the cell and is taken into an endosome.
- Endosome breaks down the virus, releasing the DNA.
- DNA travels to nucleus or cytosol and forms an episome.
- Episome may be translated and proteins expressed as a result, but it is not incorporated into chromosomes/DNA.
Describe how integrating viruses function.
- Virus with therapeutic RNA inside is injected and attaches to a cell. 2. Virus enters the cell and is taken into an endosome. 3. Endosome breaks down virus and releases RNA. 4. RNA converts to DNA. 5. DNA integrates into nuclear genome and proteins are released.
Describe how oncolytic viruses function.
- Virus containing therapeutic DNA is injected, and preferentially targets tumor cells.
- Virus replicates within tumor cell.
- Tumor cell lyses.
- Immune cells gather to help fight the cancer.
What are characteristics of an ideal vector?
High concentration of virus, convenient and reproducible, transduce dividing and non-dividing cells, can integrate or be a stable episome, target specific cells, doesn’t illicit an immune response.
How do non-viral vectors work?
Protein-coated nanoparticles can target specific cells via using the PEG chains to incorporate various ligands to target specific receptors.
What are limitations of gene therapy?
Difficult biology, short-lived nature, toxicity and immune response, issues with viral vectors.
What are uses for gene therapy?
Replace defective gene, replace normal gene, add a gene that functions in or alters a pathway.
What sequence is important in CRISPR?
PAM (NGG).
