Quantum dot coating of baculoviral vectors enables visualization of transduced cells and tissues

• The use of quantum dot (QD)-labeled viral vectors for in vivo imaging is not well investigated.
• A new method to label enveloped baculovirus with glutathione-capped CdTe QDs is developed.
• The labeling enables the identification of transduced, cultured cells based on fluorescence.
• The labeling also allows evaluation of viral transduction in a real-time manner in living mice.
• The method has the potential to assess viral vector-based gene therapy protocols in future.

Imaging of transduced cells and tissues is valuable in developing gene transfer vectors and evaluating gene therapy efficacy. We report here a simple method to use bright and photostable quantum dots to label baculovirus, an emerging gene therapy vector. The labeling was achieved through the non-covalent interaction of glutathione-capped CdTe quantum dots with the virus envelope, without the use of chemical conjugation. The quantum dot labeling was nondestructive to viral transduction function and enabled the identification of baculoviral vector-transduced, living cells based on red fluorescence. When the labeled baculoviral vectors were injected intravenously or intraventricularly for in vivo delivery of a transgene into mice, quantum dot fluorescence signals allow us monitor whether or not the injected tissues were transduced. More importantly, using a dual-color whole-body imaging technology, we demonstrated that in vivo viral transduction could be evaluated in a real-time manner in living mice. Thus, our method of labeling a read-to-use gene delivery vector with quantum dots could be useful towards the improvement of vector design and will have the potential to assess baculovirus-based gene therapy protocols in future.