Gene Therapy-Intoduction to molecular medicine Flashcards
(29 cards)
what is gene therapy?
a novel approach to treating diseases based on modifying the expressionof a person’s genes tworad a therapeutic goal
what are the types of glcassical gene therapy?
1) somatic gene therapy
2) germ line gene therapy
what is somatic gene therapy?
involves the manipulation of gene expressin in cells so as to be corrective for hte patient, but his correction in not inherited by the next generation
what is germ line therapy?
involves teh genetic modficication of germ cells that will pass the selected cahnge onto the next generation (limited to animal models)
What accidentally occured with the blood transfusion in an HIV positive patient?
the patient was given blood from a donor who had a mutation for CCR5 deletion and now the patient is essentially HIV free
what types of diseases are being treated with gene therapy?
genetic diseases; viral infections; autoimmunity; cancer; diseseases in which several genes and they enviornment interact
what are the two types of intervetnion strategies for gene therapy applications?
therapeutic stratigies
cytosolic strategies
what is the therapeutic stratigy?
vectors carry a gene that encode a protein that is either defective or that is not present due to mutations in the patients’s endogenous genes
what is the cytosolic strategy?
vector is designed to destroy or eliminate a diseased cell or tissues
what are the requirments and challenges to develope a genetic therapy?
A) gene identification adn cloning
B) Delivery
C) elements to ensure controlled gene expression
D) understanding of the host immune response
What are the limitations of genetic therapy delivery?
the delivery must be specific to the cell type and efficent and safe
What are the delivery vehicles?
Vectors; most are based on attenuated or modified versions of viruses, some use non-viral vectors (plasmid DNA)
What are the challanges of attenuated or modified viruses in gene therapy?
the challange is to remove the disease cauzeing compontes of the virus and insert recombinant genes that will be therapeutic to the patient
What are the stratageis for non-viral vectors?
plasmid DNA, liposome transfection (complexes of DNA adn lipids) or use gene gun technology
what is gene gun technology?
delivery of DNA on gold particles (primarily for DNA vacines)
why is it important to control gene expression?
to make the correct amount of therapeutic proteins at the right time (not cause other issues for the person)
and is essential for maintaining long-term expression of gene in the correct cells or tissue
What are the properties of Adenoviruses?
- episomal
- hight transduction efficiency
- infects replicating and non-replicating cells
- elicits an immune response
- insert capacity 8-36Kb
What are the properties of Adeno-associated virus?
- integrates genenome into specific region on human chr 19
- low immunogenicity
- no associated disease
- infects both dividing and non-dividing cells
- limited insert capacity ~5Kb
What are the properties of herpesviruses?
- large insert capacity
- broad host range
- infects dividing and nondividing cells
What are the properties of liposomes/ naked DNA?
- no limit to the size of the genes that can be delivered
- low immunogenicity
- poor levels of gene transfer
What are the properties of retroviruses?
- non pathogenic in humans
- stably transduces dividing but non non-dividing
- inserts genome into host cell’s DNA
- longterm expression
- insert capacity of 8Kb
- inactivated by human complement
how is a retroviral vector made?
WT gene b/n packign signals is a survival gene, insert to a cell to make a packaging cell, place the therapeutic gene also b/n the packaging signals and insert into the producer cell and get a gene therapy vector (a little confusing sorry)
what are some important components to initiate a gene therapy trial?
invovles both internal review boards (IRBs) and ferderal apporval from the FDA adn the recombinant DNA advisory committee (RAC)
can take 10-20 yrs
majority of clinical trials are being done is us (63%)
~1579 trials on going
waht is important about AAV? (adeno-associated virus vectors)
- do not stimulate inflammation in the host
- does not elicit antibodies against itself
- can enter non-dividing cells
- integrates successfully into 1 spot int eh genome of its host (chr 19)
