FIG 4.

Intercellular connections provide a route for infection of neighboring cells. (A) MDCK cells were infected at an MOI of 0.1 with IAV. At 2 h p.i., 10 mM zanamivir, 30 μM IPA-3, 100 μM paclitaxel (“Taxol”), 20 μM cytochalasin D (CytoD), and 30 μM nocodazole (Noc) were added at 2 h p.i. as indicated, and the cells were incubated for 48 h. Cells were fixed and immunostained for NP (red), and nuclei were stained with DAPI (blue). Images were taken on a fluorescence microscope (Zeiss Axiovert 200M) using a 20× objective. (B) Quantification of the microplaques (NP-positive neighboring cells, white circles) in panel A. ***, P < 0.001. (C) MDCK cells were infected at an MOI of 0.1 with IAV and treated with or without 4 mM ammonium chloride and treated as described for panel A. Cells were fixed and immunostained as described for panel A. Microplaques (NP-positive neighboring cells, white circles) are quantified in a bar graph below the images. *, P < 0.05. Counts for 70 fields of view were included per sample per trial.