Figure 1. Pathologic examination of lungs infected with the N-PRRSV on day 7 post-infection.

(A) Normal morphology observed in UNC porcine lung; (B) Interstitial pneumonia in the lung with thickening of alveolar septa accompanied with infiltration of immune cells; (C) Most viral antigen (brown) was detected in the alveolar cells and the bronchiolar epithelial cells in lesions.