Non-infected (–) and infected (+) Marc-145 whole cell extracts (15 μg) were separated by 12% SDS-PAGE, and the membrane was blotted with PRRS virus GP3 protein antibody [HL3675] (GTX641703) diluted at 1:1000. The HRP-conjugated anti-rabbit IgG antibody (GTX213110-01) was used to detect the primary antibody.