Effective Gene Transfer Using Viral Vectors Based on SV40

To date, virus-mediated gene transfer has focused principally on murine leukemia virus and adenovirus as delivery vehicles (1 ,2 ). It has become clear that these viral delivery systems are not adequate for the range of potential therapeutic needs, and other vehicles are being developed for these purposes, including adeno-associated virus, herpesvirus, and others (3 ,4 ). Each virus has advantages and disadvantages: The latter include inactivation by human complement, limited infectivity, low titers, short-lived expression, immunogenicity, contamination by replication-competent or helper virus, and so on.