Fig. 5.

DNA vaccination elicits protection from lung disease induced by A/California/2009 challenge and prevents viral replication in the lung. Lungs were collected from 5 pigs per group at 5 dpc with A/California/2009. Hematoxylin and eosin staining was performed to assess histopathology, and immunohistochemistry analysis was performed to detect influenza virus antigens in the lung. Micrographs are representative for each treatment group (including monovalent NS and NF vaccine groups) at a magnification of ×20. See Results for lesion description. In panel A, the epithelium lining the bronchiole is irregular (arrow), and prominent peribronchiolar lymphocyte infiltration (*) is evident. In the control IHC photomicrograph in panel E, virus antigen in bronchiolar epithelial cells (arrow) appears as brown coloration of the nucleus and cytoplasm.