Advances in Non-Viral DNA Vectors for Gene Therapy

Abstract

Uses of viral vectors have thus far eclipsed uses of non-viral vectors for gene therapy delivery in the clinic. Viral vectors, however, have certain issues involving genome integration, the inability to be delivered repeatedly, and possible host rejection. Fortunately, development of non-viral DNA vectors has progressed steadily, especially in plasmid vector length reduction, now allowing these tools to fill in specifically where viral or other non-viral vectors may not be the best options. In this review, we examine the improvements made to non-viral DNA gene therapy vectors, highlight opportunities for their further development, address therapeutic needs for which their use is the logical choice, and discuss their future expansion into the clinic.

Keywords: DNA vaccine; antibiotic-free plasmid; minicircle; minimized vector; miniplasmid; minivector.

Figure 1

Generation of DNA minivectors. To generate minivectors, any target sequence or expression cassette is cloned between the attB and attP sites located in direct orientation in a minivector-producing parent plasmid. λ integrase mediates the intramolecular recombination of the attB and attP sites, producing two catenated rings: the minivector containing the target sequence or expression cassette, and a miniplasmid containing all the other undesired sequences. The catenanes are unlinked by topoisomerase IV. λ Int: lambda integrase; Topo IV: topoisomerase IV; bla: β lactamase (encoding ampicillin resistance); ori: bacterial origin of replication; attP: phage attachment site; attB: bacterial attachment site; attL: hybrid attachment site to the "left" of the recombined sequence; attR: hybrid attachment site to the "right" of the recombined sequence.