Gene Therapy Flashcards
What was the first ex vivo therapy used to treat?
Treating Adenosine Deaminase Deficiency Syndrome (bubble boy syndrome)
What was the first in vivo gene therapy used to treat?
Cystic fibrosis, using adenovirus
What are the two types of classical gene therapy?
Somatic and Germline, with only somatic done in humans currently
Explain the overall process of ex vivo therapy
A tissue is removed, and treated with a retrovirus. The cells that incorporated the virus are then selected and injected back into the patient.
What are types of problems treated by gene therapy or in clinical trials?
Genetic deficiencies (i.e. OTC deficiency), Viral Infxns, Cancer, Autoimmunity, Diseases with genes and environmental intxn.
What are the most commonly research health issues being researched for gene therapy?
Cancer, monogenic diseases and cardiovascular diseases
What is the first gene therapy to be approved for treatment of disease? Where is it?
Glybera is used to treat lipoprotein lipase deficiency in Europe, and treats congenital blindness
What are the two types of intervention strategies for gene therapy applications?
Therapeutic strategies and cytolytic strategies
What is the most significant challenge in gene therapy?
Delivery of the gene therapy to a given target in a specific, safe and efficient manner
What are the two general methods of gene therapy
Using vectors from modified viruses or non-viral vectors
What is a challenge of using viral vectors
One must remove the disease causing agents of the virus and insert recombinant genes that will be therapeutic
What are examples of non-viral vectors?
Liposome transfection - complexes of DNA and lipis
Gene Gun technology - delivery of DNA on gold particles (primarily for vaccines
What is a concern when needing to do multiple doses?
If it’s a vector that doesn’t integrate into the host DNA, it cannot cause an immune response or the person will be immune to future doses.
What are the five categories of Vectors?
Adenovirus, adeno-associated virus, herpesvirus, liposomes/naked dna, retrovirus
What are the most commonly used vectors in gene therapy?
Adenoviruses and retroviruses
What types of cells can adenoviruses infect?
Retroviruses?
Adenoviruses infect replicating and non-rep cells
Retroviruses can only target replicating cells
What is the one retrovirus can enter into replicating and non-replicating cells?
HIV
Must add card based on the creation of retroviruses
yea…
What are three big problems to be solved for gene therapy to take off?
How to avoid immune responses, how to get genes into non-dividing cells like liver, muscle, and neurons, and how to get gene integrated so it will be expressed indefinitely
What are lentiviruses?
Viruses that have latency or extended periods that they remain in the body like HIV
What are four important differences between AAVs and other vectors?
AAVs:
- don’t stimulate inflammation in the host
- don’t elicit antibodies against itself
- can enter non-dividing cell
- integrates successfully into one spot in the genome of its host (still low freq)
What is an example of gene therapy success?
SCID, which resulted in 90% of treated infants becoming better
How is the treatment of leber congenital amaurosis?
Mutations of RPE65. A recombinant adeno-assoc. virus vector, altered to fix gene, restored vision in animal models.
What is insertional oncogenesis?
Possible risk with type of vector, because they repeatedly insert into cell’s chromosomes, the process that is most likely to lead to a malignant change.
Adenovirus vector properties
episomal, high transductino efficiency, infects replicating and non-replicating cells, elicits an immune response, insert capacity 8-36 kb
adeno-associated vector properties
gold standard, integrates genome into specific region on human chromosome 19 long lasting, low immunogenicity, no associated disease, infects both dividing and non-dividing tissues, limited insertion capacity
Herpes vector properties
large insertional capacity, broad host range, infects dividing and non-dividing cells
liposomes/naked dna vector properties
no limit to size of genes, low immunogenicity, poor levels of gene transfer
retrovirus vector properties
non-pathogenic, in dividing cells, inserts into genome, long term expression, insert capacity of 8 kb, inactivated by human complement
