TJAP1 and infection: The expression of PILT (tight junction protein 4) significantly (p < 0.05) increased in the MOS groups upon infection and peaked at 4 or 24 hpi, while ZO-2 (zonula occludens 2) and occludin showed a higher expression in the MOS groups at 0 hpi and then decreased gradually post-infection (p > 0.05).