Table 1.
Virus-based gene delivery methods applied to modify human pluripotent stem cells.
| Trait | Vector |
||||
|---|---|---|---|---|---|
| Retrovirus | Lentivirus | Adenovirus | Adeno-associated virus (AAV) | Baculovirus | |
| Viral genome | ssRNA | ssRNA | dsDNA | ssDNA | dsDNA |
| Packaging capacity | 8–8.5 kb | 8–9 kb | Up to 38 kb | <5 kb | No known upper limit |
| Genome integration | Yes | Yes | No | Noa | No |
| Infection | Dividing cells only | Dividing and non-dividing cells | Dividing and non-dividing cells | Dividing and non-dividing cells | Dividing and non-dividing cells |
| Transgene expression | Stable | Stable | Transient | Transient/stable | Transient/stable |
| Advantages | + Long term expression | + High transduction efficiency + Long term expression |
+ Very high transduction efficiency + High packaging capacity |
+ Site-specific integration | + High transduction efficiency + Large transgene capacity |
| Disadvantages | - Random integration site - Instability (due to methylation) |
- Random integration site | - Short term gene expression - Requires helper virus for replication |
- Small packaging capacity - Complicated process of vector production |
- Lack of permanent transgene expression - Random integration site |
kb – kilobase; ss – single stranded; ds – double stranded.
a
AAV vector genomes can persist within cells as episomes, however AAV vector integration has been observed in various experimental settings.30