Non-transfected (–) and transfected (+) Marc-145 whole cell extracts (15 μg) were separated by 15% SDS-PAGE, and the membrane was blotted with PRRS virus M protein antibody  (GTX634651) diluted at 1:500. The HRP-conjugated anti-mouse IgG antibody (GTX213111-01) was used to detect the primary antibody.