Table 1.

Advantages and limitations of the use of viral vectors in gene therapy.

Used Vectors	The Main Advantages	Limitations
Adenoviruses	High efficiency of in vivo and ex vivo transduction; High level of transgene expression; Possibility of obtaining high titre virus preparations.	Cytotoxicity; Strong immune response to viral proteins restricting repeated administration; Short-term transgene expression (no integration with the genome).
Retroviruses	Long-term transgene expression (integration with the genome).	Introduction of the transgene possible only to dividing cells; Possible insertion mutations (integration into the genome); Application limited mainly to transducing cells ex vivo.
Lentiviruses	Introduction of the transgene possible also to non-dividing cells; Long-term transgene expression;	Possible insertion mutations.
AAV (Adeno-associated viruses)	Low immunogenicity; Introduction of the transgene possible also to non-dividing cells; Long-term transgene expression.	Possible insertion mutations; Difficult quality control.
Herpes virus	Introduction of the transgene possible also to non-dividing cells; Transgenes up to 15 kbp.	Short-term expression of the transgene.