FIG 4.

pAPN may mediate PDCoV internalization via an endocytotic pathway. HEK293 cells were plated into confocal dishes, and upon reaching 80% confluence, they were cotransfected with 1 μg of the pAPN-Flag plasmid (or the control vector) and either 1 μg of Rab5-BFP (blue) (A), 1 μg of Rab7-EGFP (green) (B), or 1 μg of LAMP1-RFP (red) (C). The cells were then infected with PDCoV (MOI = 100) for 2 h at 37°C, and the N protein was visualized by an immunofluorescence assay. The colocalization ratios in the right panel were analyzed with ImageJ. Error bars represent the SD. *, P < 0.05.