Western blot analysis. Western blot analysis showed the presence of extracellular adherence protein (Eap) in the serum of animals infected with wild-type S. aureus bacterium (Lane 5, 6 and 7). No Eap was detected in the serum samples of the control animals (Lane 2, 3 and 4). Purified Eap (Lane 1) was used as a positive control. Ponceau staining was used as a loading control.