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.

Brunetti-Pierri Italian Journal of Pediatrics 2008 34:2   doi:10.1186/1824-7288-34-2