Generation of a caged lentiviral vector through an unnatural amino acid for photo-switchable transduction.

Application of viral vectors in gene delivery is attracting widespread attention but is hampered by the absence of control over transduction, which may lead to non-selective transduction with adverse side effects. To overcome some of these limitations, we proposed an unnatural amino acid aided caging-uncaging strategy for controlling the transduction capability of a viral vector. In this proof-of-principle study, we first expanded the genetic code of the lentiviral vector to incorporate an azido-containing unnatural amino acid (Nϵ-2-azidoethyloxycarbonyl-l-lysine, NAEK) site specifically within a lentiviral envelope protein. Screening of the resultant vectors indicated that NAEK incorporation at Y77 and Y116 was capable of inactivating viral transduction upon click conjugation with a photo-cleavable chemical molecule (T1). Exposure of the chimeric viral vector (Y77-T1) to UVA light subsequently removed the photo-caging group and restored the transduction capability of lentiviral vector both in vitro and in vivo. Our results indicate that the use of the photo-uncage activation procedure can reverse deactivated lentiviral vectors and thus enable regulation of viral transduction in a switchable manner. The methods presented here may be a general approach for generating various switchable vectors that respond to different stimulations and adapt to different viral vectors.