Gene delivery systems: Bridging the gap between recombinant viruses and artificial vectors.

Although most research in the field of somatic gene therapy has investigated the use of recombinant viruses for transferring genes into somatic target cells, various methods for nonviral gene delivery have also been proposed. Both types of gene delivery systems have advantages and drawbacks. Schematically, viral vectors are particularly efficient for gene delivery, whereas nonviral systems are free of the difficulties associated with the use of recombinant viruses but need to be further optimized to reach their full potential. In order to bridge the gap between viral vectors and synthetic reagents, we discuss here some specific features of the viral vector systems of today that could advantageously be taken into account for the design of improved nonviral gene delivery systems. Indeed, although nonviral systems differ fundamentally from viral systems, one possible approach towards enhanced artificial reagents aims at developing 'artificial viruses' that mimic the highly efficient processes of viral infection.