Figure 1

HKU11, HKU13 and HKU17 pseudovirus entry requires an acidic endosomal pH. DF-1 cells were pretreated with various concentrations of inhibitors at 37 °C for 2 h, and fresh DMEM with 10% FBS was added for 24 h. The optimal concentration of inhibitors for DF-1 cell viability was determined using a CCK-8 kit. DF-1 cells were preincubated with the endosomal acidification inhibitors A NH₄Cl or B Baf-A1 at the indicated concentrations, after which the cells were infected with selected DCoV spike-pseudotyped retroviruses. VSV-G pseudovirions were used as a control. Luciferase activity was used as a measure of cell entry efficiency after 48 h; error bars indicate SEM (two-tailed t test, *p < 0.05, ***p < 0.001; n ≥ 3).