Question

Describe the ideal gene therapy vector and give examples of existing vectors

Answer 1

gene therapy (also called human gene transfer) is the therapeutic delivery of nucleic acid into a patient's cells as a drug to treat disease.

Gene therapy utilizes the delivery of DNA into cells, which can be accomplished by several methods.

Genetic material can be transferred via a vector that is defined as the vehicle that is used to deliver the gene of interest. The ideal vector would transfer a precise amount of genetic material into each target cell, thereby allowing for expression of the gene product without causing toxicity.An ideal vector should deliver gene to a specific cell type, accommodate foreign genes of sufficient size, achieve the level and duration of trans-genic expression sufficient to correct the defect and be non-immunogenic and safe.

Gene transfer via the viral vectors is called transduction while transfer via the non-viral vectors is called transfection.

The viral vectors can be divided into two types: Integrating and non-integrating viral vectors.

The former, such as, retroviral, lentiviral, and adeno-associated viral vectors, can integrate into the human genome; whereas the non-integrating vector (e.g., adenoviralvector) is maintained in the nucleus without integrating into the chromosomal DNA, so that the transgene is apt to lose during cell division and expression of the foreign gene is transient.

In apackaging cell, the essential components for further propagating of viruses can be provided in trans, which enable the viral vectors to be packaged as the viral particles and to deliver genes to the targeted cells. Certainly, this is a dead-end infection, because the vectors lack the essential components for viruses’ propagation. Recombinant viral vectors can lead to the generation of infectious parental viruses. This is a principle frequently used in viral vector design in gene therapy.

Chemical transfection introduces DNA by calcium phosphate, lipid, or protein complexes. Calcium phosphate, DEAE-dextran, liposomes, and lipoplexes (for oral delivery of gene) surfactants and perfluro chemical liquids for aerosol delivery of gene