Label-free Tracking of Single Virus Entry

Deciphering the single virus entry is crucial for elucidating the complex dynamics of viral behavior and infection processes. Measuring the entry dynamics of single virus with high temporal resolution without the perturbation from exogenous artificial labels is one of the most challenging tasks. Here, we present a label-free and real-time tracking method to address this issue. By leveraging a motion analysis algorithm combined with the surface plasmon resonance microscopy (SPRM), the characteristic movements of virus in isolation and three types of virus–host interactions are identified with nanometer localization accuracy and millisecond temporal resolution. The variation of infected cell-substrate adhesion is observed by capturing the time-dependent imaging simultaneously. The intrinsic detailed motion of viral entry without the perturbation of labeling is revealed for the first time to our knowledge. We anticipate that this method will provide a new paradigm for studying viral pathogenesis mechanisms, extracellular vesicle communication and nano-based drug delivery at the single-particle level with unprecedented fidelity.