Gene Therapy

Question 1

What are the advantages of a retroviral vector and an adenoviral vector?

Answer 1

Long-term expression
High efficiency of gene delivery

High titres
No integration –> no risk of oncogenic activation
Up to 30kB as gutless.

Question 2

What are the disadvantages associated with retroviral and adenoviral vectors?

Answer 2

Viral proteins evoke immune response
Recombination –> replication competent
Oncogenic activation

Transient expression
Inflammatory and immune response
Replication competent virus by recombination.

Question 3

What are the main barriers to successful gene therapy?

Answer 3

Poor uptake, transport, and uncoating
Short term persistence of vector genome
Poor transcriptional activity and inadequate transgene expression.
Immuno response to vector or transduced cells –> loss of transduced cells.

Question 4

How has gene therapy been useful for HIV?

Answer 4

CXCR5 required for HIV infection - if mutated individuals are HIV resistant. Give infected individuals a BMT. OR using CRISPR take out HSCs and knock out receptor. Then autologous replacement

Question 5

What factors contribute to T cell leukaemia in SCID-XI patients?

Answer 5

Growth advantage of T cells expressing YC.
Retroviral Use
Immunosuppressed status of host
Anti-apoptotic effect of YC expression.

Question 6

What strategies are used to combat insertional mutagenesis?

Answer 6

Self-inactivating Y-retroviral and lentiviral vectors.
Non-integrating vectors
Preferred integration sites e.g. AAV.
Episomally maintained vectors.
Engineering suicide genes into into vectors.

Question 7

How did Y-retroviral therapy affect CGD patients?

Answer 7

long term correction but myelodysplasia in 4/4 patients.

Question 8

What other way can we target cancer cells?

Answer 8

Tumour microenvironment - Inject AAVs containing angiostatin or endostatin - reduced tumour growth in animal models.