Cutting-Edge Gene Delivery As science moves from gene discovery to understanding gene function, the need to study gene expression in a native host is becoming increasingly important. Many of these hosts are difficult or impossible to transfect, which means functional studies may be limited to hosts that easily accept DNA using traditional transfection methods. To solve this problem, viral-based gene delivery systems, like our AAV Helper-Free System, AdEasy™ adenovirus system, and ViraPort® retroviral cDNA expression system have been developed for exceptionally high-efficiency gene delivery to a broader range of hosts.