FIG 6 .

MHV-induced macropinocytosis is associated with, but independent of, syncytium formation. (A) DBT cells were mock infected or infected with MHV A59 at an MOI of 1 PFU/cell for 8 h, treated with PEG for 1 min, washed, and incubated for 3 h or transfected with VSV-G for 24 h. Nanoparticles were added 3 h prior to fixation, and cells were washed, fixed, stained, and imaged. Syncytia with ≤10 nuclei were analyzed. Data are represented as the mean ± the standard error of the mean of two replicates, each performed in duplicate. n = ≥30 cells per replicate. (B, C) Cells were mock infected or infected with MHV at an MOI of 1 PFU/cell. Anti-CEACAM blocking antibodies were added at 2 hpi, nanoparticles were added at 5 hpi, and cells were washed, fixed, stained, and imaged at 8 hpi. The number of nuclei per syncytium (B) and the percentage of cells with internalized nanoparticles (C) were measured. Significance was assessed by one-way ANOVA with Dunnett’s post hoc test. ***, P < 0.0001; **, P < 0.01; *, P < 0.05; n.s., not significant.