Table 1.

Classification of the vectors used in suicide gene therapy of cancer.

Vector Type	Vector Subtype	Advantages	Disadvantages	References
Viral vectors	Retrovirus/Lentivirus	Long-term transgene expression, Integrates the gene into host genome, Low immunogenicity.	Safety concerns (insertional mutagenesis).	(Yi et al. 2011; Dass, Choong 2007; Braybrooke et al. 2005).
	Adenovirus	Effect on dividing and non-dividing cells, Lower risk of host genome integration.	Safety concern (high immunogenicity), Transient transgene expression.	(Wold, Toth 2013; Kim et al. 2012; Majhen et al. 2014).
	Adeno-associated virus	Medium to high transgene expression, Effect on dividing and non-dividing cells, No significant immunogenicity.	Low DNA loading capacity, Safety concerns (possibility of insertional mutagenesis).	(Santiago et al. 2016; Mingozzi, High 2013; Dass, Choong 2007; Münch et al. 2013).
Non -viral vectors	Synthetic polymers and lipids	Ease of preparation, Lower cost, Lower immunogenicity.	Lower transfection efficiency.	(Voges et al. 2003; Kang et al. 2009; Cortez et al. 2015).
	Amino acid-based vectors	Monodisperse and uniform constructs, ability to fine tune structure.	Lower transfection efficiency.	(Canine et al. 2009; Wang et al. 2011; Nouri et al. 2013).
	Bacteria-based vectors	Large capacity for suicide enzyme loading, Bacterial minicells (BMCs) are non-infectious.	Safety concern (Infection by using live bacteria).	(Hoffman, Zhao 2014; MacDiarmid, Brahmbhatt 2011; Tsuji et al. 2016).
	Cell-based vectors	Tumor tropism, Self-isolated cells without the immunogenicity concerns	Low efficiency of tropism, High costs Safety concern (Unknown fate).	(Aboody et al. 2013; On et al. 2001; Nouri et al. 2015).