Non-viral vectors
Viral vectors are highly efficient but when it comes to large scale production at the commercial level, non-viral serve as a better choice. These methods produce low immunogenic response and hence are also considered to be safe. With the recent advancement in this area the efficiency of transfection has also improved (Anderson, N.D). The best examples of non viral vectors include:
- Naked DNA: Plasmid DNA is the best example of naked DNA whose structure is simple and commercial production is relatively cheap. They get easily incorporated into the host genome and do not produce immune response. This naked DNA is directly injected into the desired cells (Gould and Favorov, 2003).
Apart from these few other non viral methods include, the use of DNA complexing reagents, liposomes etc.
Table 1: A table showing comparison of vectors (Gould and Favorov, 2003, Table 1)
|
Vector
|
Transgene capacity
|
Immunogenicity
|
Genome integration
|
Long-term expression
|
Transfer into dividing (D) and quiesent (Q) cells
|
|
Plasmid-naked
|
Unlimited
|
Low
|
No
|
Only in muscle
|
D and Q
|
|
Plasmid-complexed
|
Unlimited
|
Low
|
No
|
No
|
D and Q
|
|
Ad 1st generation
|
5 kb
|
High
|
No
|
No
|
D and Q
|
|
Ad 2nd generation
|
8 kb
|
High
|
No
|
No
|
D and Q
|
|
Ad gutless
|
37 kb
|
Less
|
No
|
Longer
|
D and Q
|
|
AAV
|
4 kb
|
High
|
Yes and episomal
|
Yes
|
D and Q
|
|
HSV
|
35 kb
|
High
|
No
|
Yes
|
D and Q
|
|
Retrovirus
|
Up to 8 kb
|
Low
|
Yes
|
Yes
|
D
|
|
Lentivirus
|
Up to 8 kb
|
Low
|
Yes
|
Yes
|
D and Q
|