IFNB1 and infection: To confirm that axonal IFN exposure has no effect on retrograde RABV infection, we used time-lapse video microscopy with high temporal resolution (> 10 frames/sec) to track the number of RABV particles transported retrograde into the M compartment in the presence or absence of IFNβ or IFNγ between 2–4 h post-axonal infection (Fig 4A).