Figure 4

Histopathological lesions in pigs infected with Salmonella Choleraesuis at 21 days post-infection. A Lung of an animal from the positive control group presenting a moderate mixed interstitial inflammatory infiltrate (*), mainly composed of macrophages (MΦs) and lymphocytes (inset). B Lung of an animal from the immunized group showing a light thickening of the septa (*), due to infiltrate particularly of MΦs (inset). C Tracheobronchial lymphoid node of an animal from the positive control group presenting severe lymphoid depletion and compared with an animal from the immunized group (D). Haematoxylin–eosin stain.