Viral gene delivery systems, features

This section will describe the features and clinical applications for each gene delivery system. The description will start with a common feature of both viral and nonviral gene delivery systems, the expression cassette for the therapeutic protein. 

TABLE 15.2. Key features of viral and nonviral gene delivery systems... 

Viruses Viruses provide a unique and extremely efficient method of insertion of genes into mammalian cells, such as human bone marrow stem cells. SV 40, adenovirus, vaccine virus, and polyomavirus have been used as gene transfer vectors. A non-replicating adenoviral vector that efficiently infects human cells has recently been developed. The essential feature of a retroviral gene delivery system is the presence of an RNA copy of the replacement gene that is packaged in a viral particle, capable of specific and efficient entry into the cytoplasm of a cell. A retrovirus consists of... 

Nonviral gene transfer systems are based on a variety of technologies that employ physical/chemical means to deliver genes [6], These technologies include direct plasmid injection, bombardment with DNA coated microprojectiles, and DNA complexed with liposomes or polymers. Some nonviral transfection techniques are too inefficient (e.g., coprecipitation of DNA with calcium phosphate [7], DNA complexed with diethylaminoethyl (DEAE)-dextran [8], electroporation [9]), or laborious (e.g., microinjection of DNA [ 10 ]) for clinical use. Only those gene delivery systems (viral and nonviral) with potential for clinical application are discussed in this chapter. The main features of these technologies (Table 18.3) are described and specific examples of their applications highlighted. 

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