Figure 4

Differential tropism of genotype I-E70 and genotype II-BEL strains in the respiratory epithelial cells. A In vitro infection of E70 (left) and BEL18 (right) strains in respiratory epithelial cells. Cells were inoculated via apically, basolaterally, or apically after EGTA treatment. ASFV-infected cells were counted at 24, 48, and 72 hpi. Statistical significance was analyzed using two-way ANOVA followed by Tukey’s multiple comparison post hoc test. Different letters indicate significant differences (p < 0.05) between different time points. Data are presented as mean of three independent experiments ± SD. B Representative IF pictures of ASFV-infected PoRECs. Immunofluorescence staining was performed against ASFV p72 (green), cytokeratin (red), and nuclei (blue). The pictures show basolateral side infection of E70 (top) and apical side infection of BEL18 (bottom) in the respiratory epithelial cells for 72 h infection. Images were captured using either a 20× or 63× objective lens. Arrows indicate infected cells. In the images taken at 63× magnification, white arrows indicate cytokeratin⁺ infected cells, while yellow arrows point to cytokeratin⁻ infected cells. Scale bar: 50 μm.