Immunohistochemistry: A Rapid and Specific Diagnostic Tool for Influenza Virus Infection in Pigs

Abstract

During the 2016 spring, a local outbreak of severe dyspnea, seromucous nasal secretion, anorexia and loss of productive performance was identified in an intensive pig farm in southern Chile. Samples of diseased animals were submitted to the Diagnostic Laboratory of the Faculty of Veterinary Medicine, in Chillan, Chile, for pathological and histopathological study. Macroscopically, lungs appeared to be congested, edematous and “non-collapsed”, which could be related to lesions compatible with interstitial pneumonia. Microscopic lesions showed a variable thickening of the septa, epithelial necrosis of the airways, diffuse inflammatory infiltration surrounding bronchial and bronchiolar areas, inflammatory exudate in the alveolar spaces with activate alveolar macrophages and fibrin. All lesions were compatible with Swine Influenza Virus (SIV) infection, and we successfully confirmed through SIV nucleoprotein immuno histochemistry staining of said samples, by utilizing a rapid and specific first-line diagnostic method that allows a rapid decision-making tool to control the spread of the virus. Additionally, the presence of the virus was confirmed by a serological field study.