Expression of recombinant adenoviruses (rAdV) in vitro. Western blot analysis of A549 cell lysates from mock infected (lane 1) or infected with rAdV (MOI of 1) expressing GFP (lane 2), M-GP5 (lane 3) and M-GP5m (lane 4). Immunoblot was performed using GFP-specific mouse monoclonal antibody or a convalescent PRRSV-specific pig antiserum as primary antibody and an anti-mouse or anti-pig IgG-HRP as secondary antibody. Replication capability of rAdV was confirmed by E1A expression (lanes 2–4). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) immunostaining was used as a loading control.