Gene Therapy (Dr. Whitt)

Question 1

What is the manipulation of gene expression in cells so as to be corrective for the pt but the correction is not inherited in the next generation?

Answer 1

somatic gene therapy

Question 2

What involves the genetic modification of germ cells that will pass the selected change onto the next generation

Answer 2

germline gene therapy

Question 3

Describe ex vivo gene therapy.

Answer 3

A piece of tissue is taken from individ –> applied gene therapy (treated with viral vector) –> corrected tissue incorporated back into indiv

Question 4

What disease is currently beinf treated with gene therapy (in europe)?

Answer 4

LPL deficiency (agent= Glybera)

Question 5

T or F: there are no FDA approved gene therapy products currently on the market

Answer 5

true

Question 6

What is the difference between therapeutic strategies and cytolytic strategies of intervention with gene therapy?

Answer 6

therapeutic: vector carries a gene that encodes for a protein that is either defective or not present bc of mutation(s) in the pt’s gene(s)

Cytolytic: vector designed to kill diseased cells or tissues (ex: virus vector with thymidine kinase + target tissues with prodrug –> toxic product)

Question 7

What are the steps for the development of a gene therapy? (4)

Answer 7

1. ID gene and clone it
2. develop gene vector for delivery of gene
3. develop elements to control expression of therapeutic gene
4. control host immune response to therapy

Question 8

What is the basis of most vectors/ What are they derived from?

Answer 8

MOST are attenuated or modified versions of viruses (some others are liposomes and “gene guns”

Question 9

What are the properties of adenovirus vectors? (7)

Answer 9

1. episomal (i.e. a plasmid)
2. high transduction efficiency
3. infects both replicating and non-replicating cells (BUT later he says they only infect dividing cells)
4. elicits immune response (inflammation= potentially dangerous)
5. insert capacity of 8-36kb
6. non enveloped
7. DNA that does not integrate into chromosome

Question 10

What are the properties of adeno-associated virus vectors? (5)

Answer 10

1. integrates into sp region of chromosome 19
2. low immunogenicity
3. no associated disease
4. infects both dividing and non-dividing cells
5. limited insert capacity to 5kb

Question 11

What are the properties of herpes virus vectors? (3)

Answer 11

1. large insert capacity
2. low immunogenicity
3. poor levels of gene transfer``

Question 12

What are the properties of retrovirus vectors? (6)

Answer 12

1. non-pathogenic in humans
2. stably transduces dividing cells ONLY
3. inserts genome into host DNA
4. long term expression
5. insert capacity of 8kb
6. inactivated by human complement

Question 13

In a retrovirus, the therapeutic gene is inserted betweenv______

Answer 13

packaging sequences

Question 14

Unlike other genen therapy vectors, adeno-associated virus vectors… (4 things are different)

Answer 14

1. does not stimulate inflammation
2. does not elicit Ab against itself
3. can enter non-dividing cells
4. integrates successfully into one spot in the genome (chrom 19 in humans)