Table 2.

General features of common viral vectors for nucleic acid therapeutic delivery

Viral vector	Basic characteristics	Advantages	Limitations
Adenoviruses	•∼26- to 48-kb double-stranded DNA genome •non-enveloped •non-integrating	•high capacity •transduction of both dividing and non-dividing cells •broad tropism	•high immunogenicity (especially earlier generations) •preexisting immunity prevalent in general population
Lentiviruses	•∼9.7-kb single-stranded RNA genome •enveloped •integrating in nature, non-integrating versions available	•low immunogenicity •integration allows stable gene expression •transduction of both dividing and non-dividing cells •broad tropism	•risk of insertional mutagenesis •moderate capacity
Adeno-associated viruses	•∼4.7-kb single-stranded DNA genome •non-enveloped •non-integrating	•low immunogenicity •minimal health risk as the wild-type virus is not known to cause disease •ease of cloning due to small genome •diffusion through dense tumor mass due to small size •transduction of both dividing and non-dividing cells •broad tropism	•low capacity •requires complementary strand synthesis in host, hence delayed transgene expression, or double-stranded versions need to be generated
HSVs	•∼152-kb double-stranded DNA genome •enveloped •non-integrating	•high capacity •transduction of both dividing and non-dividing cells •broad tropism, including neuronal tropism	•health risk as the wild-type virus is highly dangerous