Incorporation of quantum dots on virus in polycationic solution

Jin-Oh You¹, Yu-San Liu², Yu-Chuan Liu¹, Kye-Il Joo¹, Ching-An Peng^1,2

¹Department of Chemical Engineering and ²Department of Materials Science, University of Southern California, Los Angeles, CA, USA

Abstract: Developing methods to label viruses with fluorescent moieties has its merits in elucidating viral infection mechanisms and exploring novel antiviral therapeutics. Fluorescent quantum dots (QDs), an emerging probe for biological imaging and medical diagnostics, were employed in this study to tag retrovirus encoding enhanced green fluorescent protein (EGFP) genes. Electrostatic repulsion forces generated from both negatively charged retrovirus and QDs were neutralized by cationic Polybrene^®, forming colloidal complexes of QDs–virus. By examining the level of EGFP expression in 3T3 fibroblast cells treated with QDs-tagged retroviruses for 24 hours, the infectivity of retrovirus incorporated with QDs was shown to be only slightly decreased. Moreover, the imaging of QDs can be detected in the cellular milieu. In summary, the mild method developed here makes QDs-tagged virus a potential imaging probe for direct tracking the infection process and monitoring distribution of viral particles in infected cells.

Keywords: endocytosis, infection, envelope protein, Polybrene^®, quantum dots, retroviral transduction