Figure 1: Cytopathic effects of PRRSV on MARC-145 cells (A, B) and porcine alveolar macrophage (PAM) cells (C, D). Cells were infected with a multiplicity of infection of 5 and incubated for 24 h for PAMs or 48 h for MARC-145 cells for microscopy. CPE develops faster in macrophages than in MARC-145 cells.