Certain viruses are used for this purpose. Though viruses are the most efficient carriers available at present, they, however, have certain disadvantages. One of these is the attack by the immune system of the host resulting in damage to the introduced gene. Other disadvantages include, the limited size of the gene that can be delivered, and the unexpected response of the viral gene as well. The other method is non-viral delivery which includes chemical as well as physical means of delivering the gene.
Cationic liposomes provide a promising vector for use in gene therapy.
There are many advantages to using liposomes. First of all, it does not limit the size of DNA that can be carried into the cell. Also, it is not prone to attack by the immune system, lipid toxicity is relatively low, and it can be produced rather easily. But as of now it is much lower in efficiency compared to the viral method possibly because the optimum conditions of DNA delivery and stability have not yet been fully worked out. The purpose of this lab's research is to find out optimal condition for delivery so as to increase the efficiency of the cationic liposome in delivering the gene into the cell.