Lecture 19- Viral Vectors & Gene Therapy I Flashcards
(31 cards)
What is the main purpose of gene therapy?
The treatment of a genetic disease by introducing specific functional genetic altering material into a patient.
What are the types of gene therapy?
Gene Replacement, Gene Silencing, Gene Addition, Gene Editing.
What is Gene Replacement?
Delivery of a functional gene to replace a non-functional gene.
What is Gene Silencing?
Inactivation of a mutated gene that has become toxic to cells.
What is Gene Addition?
Over-expression of an exogenous gene to impact cellular function.
What is Gene Editing?
A permanent manipulation of a gene in a patient’s genome.
What is the overall aim of gene therapy?
Expression of the therapeutic protein for the whole life of the patient.
What are the desired properties of viral vectors for gene therapy?
Efficient gene delivery to target tissues/cells.
What are the two groups of viruses based on expression?
Transient expression and Integrative.
What is transient expression?
Short term expression; foreign genetic material is not integrated into the host genome.
What is integrative expression?
Permanently incorporated into host cell/DNA genome.
What is the general strategy for engineering a virus into a viral vector?
Involves Vector DNA, Helper DNA, Viral Proteins, and Viral Structural Proteins.
What does Vector DNA contain?
The therapeutic expression cassette along with non-coding viral cis-acting elements.
What is the function of Helper DNA?
Contains genes essential for viral replication.
What is the role of Viral Proteins?
Required for replication of the vector DNA.
What do Viral Structural Proteins do?
Recognize the vector to result in packaging of just the vector DNA.
What are adenoviral vectors known for?
Infecting dividing and non-dividing cells with high efficiency and low pathogenicity.
What are the advantages of first-generation adenoviral vectors?
Can carry large inserts and have low pathogenicity.
What is a disadvantage of first-generation adenoviral vectors?
They are very immunogenic and can be cleared by cytotoxic T lymphocytes.
What are the advantages of second-generation adenoviral vectors?
More space for larger transgene cassettes and elicited less of a host immunogenic response.
What is a disadvantage of third-generation adenoviral vectors?
Production requires additional adenoviral ‘helper’ virus.
What is a key characteristic of adeno-associated viruses (AAV)?
They are non-integrative and have a single stranded DNA genome.
What is a disadvantage of AAV vectors?
Many people have prior exposure to AAVs, giving them immunity.
What is a key feature of retroviruses?
They have a ssRNA genome and can only infect dividing cells.
