Figure 5

Macroscopic and microscopic tissue lesions and immunohistochemistry results for infected pigs. All pigs were euthanized for autopsy at 63 dpv, and their lung tissues were collected and analysed. Macroscopic and microscopic tissue lesions and immunohistochemistry analysis of infected pigs. A, C The macroscopic lesions and scores of the lungs were estimated by assigning a number to each lobe to reflect the approximate percentage of the entire lung represented by that lobe. B, D Pig lung slices stained with haematoxylin and eosin (HE). The degree and severity of interstitial pneumonia were taken into account when the microscopic lesion and score of the lung tissues were calculated: 0, no lesion; 1, mild/focal; 2, moderate/multifocal; 3, moderate/diffuse; and 4, severe/diffuse. Three pathologists evaluated the lung lesions, both microscopically and macroscopically, via blind examinations. E Detection of the PRRSV-N protein in the lung tissue of pigs via an IHC assay. The blue arrows indicate thickening of the alveolar septum and a decrease in the alveolar space; the black arrows indicate infiltration of inflammatory cells; and the red arrows indicate positive signs of PRRSV.