Goblet cell numbers were detected using PAS and AB staining assays. Microscopy magnification in a and b: 200 × . Scale bar: 100 μm. Microscopy magnification in c and d: 400 × . Scale bar: 50 μm. A PAS-stained goblet cells (a, b) and AB-stained goblet cells (c, d). a and c Jejunum of control pigs, b and d jejunum of PRRSV-infected pigs. B Relative MUC2 mRNA expression detected by relative RT-qPCR. Data are expressed as the mean ± SEM. * p < 0.05, ** p < 0.01, *** p < 0.001.