Pathological Changes in Pigs Naturally Infected with Influenza A/Sw/UP India IVRI01/2009 H1N1 Pandemic Virus and its Tissule Localization using Immunohistochemistry

Disease outbreaks among pigs with history suggestive for swine influenza in different farms were investigated. Unusual clinical signs such as fever, lethargy, anorexia, nasal discharge and occasional coughing were noticed in the pigs raised in four different farms located in the Uttar Pradesh state in India. At necropsy, lung revealed red, plum-colored consolidated areas in several lobules, most frequently in the cranial and middle lobes and sometimes involving the diaphragmatic lobe also. The main histopathological findings were epithelial degeneration and necrosis, lymphocyte infiltration in the epithelial lining and lamina propria of bronchioles and lymphocyte infiltrations in the bronchial and peribronchiolar areas. Infection with pandemic influenza A/Sw/UP-India/IVRI01/2009 H1N1 virus was confirmed by RT-PCR and imm unohistochemical detection of influenza A virus nucleoprotein in the lesions. This report describes the pathological lesions and distribution of viral antigen in the lungs of pigs naturally infected with the influenza A/Sw/UP-India/IVRI01/2009 H1N1 virus.