Abstract
Recombinant adeno-associated virus (rAAV) vectors are considered ideal vehicles for human gene therapy. Meanwhile, non-viral strategies, such as transfection agents (TAs), have also shown promise to deliver genetic materials, such as siRNA. Transduction with the rAAV vector is performed concurrently with transfection with plasmid DNA or RNA. In the present study, we report that various TAs inhibited rAAV-mediated transgene expression at diverse levels. Overall, cationic polymers and dendrimers dramatically blocked rAAV transduction, while lipid-based liposomes displayed the least effect. The inhibitory effect was dependent on the dose of TAs and the timing of infection, suggesting that the early stages of viral infection were involved. In addition, the present results indicate that the transgene expression of rAAV vectors was significantly increased by liposome-mediated transfection with adenoviral helper genes. At the same time, this was dramatically inhibited by liposome-mediated transfection with the trichosanthin gene encoding a type I ribosome-inactivating protein isolated from traditional Chinese medicine. Furthermore, liposomes also have little effect on rAAV-mediated transgene expression in vivo. Taken together, these findings suggest liposome as the best choice of TAs, which should be used in combination with rAAV-mediated gene therapy.