Table 2.

The advantages and disadvantages of main viral vectors used to transfer hSSTr2.

Vectors	Advantages	Disadvantages	References
Adenovirus	(1) Stability (2) High titers (3) Infecting dividing and nondividing cells (4) High level expression of transgene (5) Not integrating into host chromosome	(1) Strong immune response (2) Potential replication competence (3) Short-term expression (4) Demanding packaging cell line (5) Small insert size (6) No targeting	[103–105]
Adenoassociated virus	(1) No associated disease (2) Long-term gene expression (3) Integrating into human chromosome 19	(1) Extensive antiviral immunity (2) Helper-dependent replication (3) Poor host tropism (4) Small insert size: about 5 kb	[106]
Retrovirus	(1) Integrating into host cell genome (2) Reverse transcription of the RNA genome (3) Infecting dividing cells (4) Long-term expression (5) Fairly high titers	(1) Immune-related toxicity (2) Infecting dividing cells (3) Potential replication competence (4) Insertion mutation (5) No targeting	[107, 108]
Vaccinia virus	(1) Cytolytic viral vector (2) Preferentially infecting rapid dividing cells (3) Difficult to leak from normal vasculature (4) The vector itself serving as a therapeutic method (5) Large insert size: ≥25 kb DNA	(1) Live infectious lytic virus (2) Replication competence (3) Short-term gene expression (4) Postvaccinal encephalitis and progressive complications (5) No targeting	[109, 110]