Lipid-specific labeling of enveloped viruses with quantum dots for single-virus tracking

Abstract

Virus infection in host cells is a complex process comprising a large number of dynamic molecular events. Single-virus tracking is a versatile technique to study these events. To perform this technique, viruses must be fluorescently labeled to be visible to fluorescence microscopes. Quantum dot is a kind of fluorescent tags that has many unique optical properties. It has been widely used to label proteins in single-molecule tracking studies, but rarely used to study virus infection, mainly due to lack of accepted labeling method. In this study, we developed a lipid-specific method to readily, mildly, specifically, and efficiently label enveloped viruses with quantum dots by recognizing viral envelope lipids with lipid-biotin conjugates and recognizing these lipid-biotin conjugates with streptavidin-quantum dot conjugates. Such a method is superior to the commonly used DiD/DiO labeling and the other QD labeling methods. It is not only applicable to normal viruses, but also competent to label the key protein-mutated viruses and the inactivated high virulent viruses, providing a powerful tool for single-virus tracking.