Figure 1

Identification of lungs infected with H-PRRSV and N-PRRSV. Lungs of uninfected negative control and experimentally infected pigs were processed routinely for haematoxylin and eosin (H&E) staining and were re-isolated of H-PRRSV and N-PRRSV viruses and then were identified by IFA and EM. Histopathology examination showed an interstitial pneumonia and emphysema in the lungs with thickening of the alveolar septa accompanied with infiltration of mononuclear cells from both H-PRRSV affected pigs and N-PRRSV affected pigs compared to the lungs of negative control pigs. Viral re-isolates were successfully recovered from lungs of the infected pigs, but not from those of uninfected negative control pigs. Specific immunofluorescence and PRRSV particles in MARC-145 cells infected with re-isolated either H-PRRSV or N-PRRSV was observed by IFA and EM, respectively, but not from those of uninfected negative control group. a. Representative images of HE stained lungs sections from H-PRRSV infected(C), N-PRRSV infected(E), and uninfected negative control (A), original magnifications: ×40.; b. Assessment of H-PRRSV(B) or N-PRRSV(C) re-isolated infected MARC-145 cells or negative control(A) by IFA staining at 48 h; c. H-PRRSV particle(A) and N-PRRSV particle(B) under the electron microscopy (EM).