“…[31][32][33][34] The higher efficiency of viral vectors at delivering genes in vivo than nonviral vectors is illustrated by a direct comparison in which luciferase transgene activity was 10-fold higher in rat cardiac grafts transduced with an adenoviral vector compared with a plasmid vector. 35 None the less, even with viral vectors, investigators have documented inefficient gene transfer by allograft perfusion, with most studies reporting less than 1% of the cells expressing the transgene. 30,33 Although appealing because they can transduce a wide variety of cell types relatively efficiently, adenoviral vectors induce an exuberant immune response and can be especially problematic in human gene therapy applications, in that many individuals have pre-existing immunity to adenovirus.…”