Fig. 4.

Presence of virus particles in uninfected cells that are contacted by projections originating from a PRV-infected cell. ST cells were inoculated at a MOI of 0.001 with a PRV strain that expresses a GFP-tagged VP26 capsid protein (green). At 2 hpi, virus-neutralizing antibodies were added to the medium. At 7 hpi, cells were paraformaldehyde-fixed, permeabilized, and stained for actin (red). Infected cells could be identified by a strong VP26-GFP signal in the nucleus. Pictures show an infected cell with projections contacting an originally uninfected cell, with Upper images showing an overlay of different confocal sections through the cells, and Lower images showing a single confocal section through the center of the originally uninfected cells. (Inset) An enlargement of the boxed area. Arrowheads indicate virus particles in the cytoplasm of the originally uninfected cell. (Bar, 10 μm.)