Self-biotinylation and site-specific double labeling of baculovirus using quantum dots for single-virus in-situ tracking.

Single-virus labeling and tracking represent a powerful tool to study virus-cell interactions. Using baculovirus as a model, here we developed a biochemical method for labeling both the viral envelope and the viral capsid of a virus. Viral envelope of the baculovirus AcMNPV was self-biotinylated and site-specifically conjugated with quantum dots (QDs) following one-step binding reaction, while the viral nucleocapsid was site-specifically labeled with green fluorescent protein (GFP) during viral replication. The established procedure of labeling did not affect viral infectivity, showing that the double-labeled virus retained functional structure and could be tracked for viral localization and movement in the host cells. The double-labeled virus also demonstrated the potential to be used for in-situ and real-time visualizing the internalization of a single viral particle into the host cells. Furthermore, the disassembly processes of the viral envelope and the viral nucleocapsid could be monitored for a long period of time (up to 2 h). Using the established method, several interaction details between the labeled baculoviruses and the host cells have been revealed. Given its advantages in high efficiency, high specificity, convenience and the maintenance of viral infectivity, the established approach provides a promising means for elucidating virus-cell interactions.