Figure 4. Live-cell microscopy demonstrates co-localization and co-tracking of MHV with endosomal vesicles and fusion of MHV in these vesicles.

HeLa-mCC1a cells transfected with plasmids encoding RAB5-mRFP, RAB7-mRFP, or dsRed-LAMP1 were inoculated with DyLight 488-labeled MHV. Live cell imaging was performed to track internalized particles. A) Examples of MHV particles co-localizing with RAB5-, RAB7-, and LAMP1-positive endosomal vesicles. Size bars indicate 0.2 µM B) Virus particles that could be tracked were classified as ‘fusing’ (Fusing) ‘associating/dissociating’ (Assoc/Dissoc), or ‘non-fusing’ (Non-fusing) as described in the Materials and Methods section.