Fig. 6.

DNA vaccination elicits protection from lung disease induced by A/Ohio/2007 challenge and prevents viral replication in the lung. Lungs were collected from 5 pigs per group at 5 dpc with A/Ohio/2007. 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 at a magnification of ×20, except for one animal immunized with a trivalent NF vaccine in which virus was detected. 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 D, virus antigen in bronchiolar epithelial cells (arrow) appears as brown coloration of the nucleus and cytoplasm.