First outbreak of respiratory disease associated with swine influenza H1N2 virus in pigs in Korea.

This report describes the first diagnosis of swine influenza H1N2 virus infection in growing pigs in Korea by virus isolation, reverse transcription-polymerase chain reaction (RT-PCR), histopathology, and in situ hybridization. The subtype of swine influenza virus isolates was determined to be H1N2 by RT-PCR. The most consistent and predominant histological feature was bronchointerstitial pneumonia. Lung tissues from these pigs were hybridized with the nonradioactive digoxigenin-labeled complementary DNA (cDNA) probe from H1 HA and N2 NA genes but not from H3 HA and N1 NA genes. A strong hybridization signal was seen in bronchial- and bronchiolar-lining epithelial cells and in alveolar and interstitial macrophages.