| Vector |
Advantages |
Disadvantages |
| Retrovirus |
Efficient transfer |
Transfers DNA only to dividing cells, inserts randomly; risk of producing wild-type viruses |
| Adenovirus |
Transfers to nondividing cells |
Causes immune reaction |
| Adeno-associated virus |
Does not cause immune reaction |
Holds small amount of DNA; hard to produce |
| Herpes virus |
Can insert into cells of nervous system; does not cause immune reaction |
Hard to produce in large quantities |
| Lentivirus |
Can accommodate large genes |
Safety concerns |
| Liposomes and other lipid-coated vectors |
No replication; does not stimulate immune reaction |
Low efficiency |
| Direct injection |
No replication; directed toward specific tissues |
Low efficiency; does not work well within some tissues |
| Pressure treatment |
Safe, because tissues are treated outside the body and then transplanted into the patient |
Most efficient with small DNA molecules |
| Gene gun (DNA coated on small gold particles and shot into tissue) |
No vector required |
Low efficiency |
| Source: After E. Marshall, Gene therapy’s growing pains, Science 269:1050-1055, 1995. |