Table 1.
Overview of gene therapy vectors.
| Genetic material | Packaging capacity | Vector genome forms | Advantages | Disadvantages | |
| Retrovirus | RNA | 8 kb | Integrated | - High efficiency integration | - Transduction only in dividing cells |
| - No viral immune response | - Insertional carcinogenesis | ||||
| - Long-term expression | |||||
| Lentivirus | RNA | 8 kb | Integrated | - Non-dividing cells | - Integration into active genes |
| - Long-term expression | - Risk of replication competent HIV | ||||
| Adenovirus | dsDNA | Up to 35 kb (HDAd) | Episomal | - Non-dividing cells | - Acute toxicity |
| - Large cloning capacity | |||||
| - High transduction levels | |||||
| - Long-term expression (HDAd) | |||||
| Adeno-associated vectors | ssDNA | 5–9 kb | Episomal (> 90%) | - Non-dividing cells | - Limited cloning capacity |
| Integrated (< 10%) | - Long-term expression | - CTL-mediated immune reaction | |||
| Naked plasmid DNA | dsDNA | Unlimited | Episomal | - Non dividing cells | - Low efficiency of transduction |
| - No inflammatory response | - Efficient and clinically relevant delivery method still to be developed | ||||
| - Large cloning capacity | |||||
| - Long-term expression | |||||
| - Ease preparation |
dsDNA = double stranded DNA; ssDNA = single stranded DNA; HDAd = helper-dependent adenoviral vector; CTL = cytotoxic T lymphocyte.