Table 1. Frequently used approaches to transduction in tumors.

	Viral vectors				Nonviral vectors
Features	RV	LV	AV	AAV	liposomal	mRNA	transposon/ transposase
Structure	ssRNA	ssRNA	dsDNA	ssDNA
Infected cell	dividing cells	dividing and quiescent cells	dividing and quiescent cells	dividing and quiescent cells		dividing and quiescent cells
Integration	Yes	Yes	No	Yes	No	No	poor
Clinical applications	most widely used now				most widely used nonviral vectors		less been applied but have great potential
General advantage	higher infection rate				safety, ability to transfer large size gene, less toxicity
General chanllege	immunogenicity, carcinogenicity, poor target cell specificity, inability to transfer large size genes				low transfection efficiency, poor transgene expression
Cost of production	costly and laborious				cheap and relatively simple

AAV, adeno-associated virus vector; AV, adenovirus vector; dsDNA, double-stranded deoxyribonucleic acid; LV, lentiviral vector; mRNA, messenger ribonucleic acid; RV, retroviral vector; ssDNA, single-stranded deoxyribonucleic acid; ssRNA, single-stranded ribonucleic acid.