Emerging Considerations in Virus-Based Gene Transfer Systems

Accompanying the development of molecular biological tools for identifying gene sequences and functions has been the development of novel gene transfer vectors for shuttling gene sequences between different organisms. As illustrated in Fig. 1, a search of the PubMed database reveals a large number of publications describing the application of frequently used recombinant viruses. The use of these vector systems has continued to increase significantly since the publication of the 4th edition of this book in 2006. This increase has been driven by several factors, including the proliferation of gene therapy protocols (Fig. 2), the increased recognition of the general utility of viral vectors as gene transfer agents for elucidating and studying gene function, and the increased commercial access of the reagents required to produce these viral vectors. Additionally, our understanding of the molecular biology of a wide variety of virus families has increased to the point where novel chimeric viruses, containing the unique properties of two or more viruses, are being constructed routinely. Due to their unique nature, these viruses pose special challenges in risk assessment.