Submitted to: Veterinary Pathology Proceedings of the Annual Meeting of the American Coll
Publication Type: Proceedings
Publication Acceptance Date: 6/24/2002
Publication Date: 9/20/2002
Citation: GRUBOR, B., MEYERHOLZ, D.K., GALLUP, J.M., LEHMKUHL, H.D., ACKERMANN, M.R. PARAINFLUENZA VIRUS-3 PULMONARY LESIONS ARE NOT ENHANCED BY BOVINE VIRAL DIARRHEA VIRUS. VETERINARY PATHOLOGY PROCEEDINGS OF THE ANNUAL MEETING OF THE AMERICAN COLL. 2002. v. 39(5). p. 637, #97.
Technical Abstract: Parainfluenza virus-3 (PI-3) is a common respiratory pathogen of cattle and sheep. Bovine viral diarrhea virus (BVDV) is a common bovine pathogen that may enhance respiratory disease. Two groups of neonatal lambs were inoculated intranasally and intratracheally with PI-3/BVDV or PI-3 alone. Both infected lambs and controls (receiving only media) were bled and euthanized 3, 6, and 17 days post-inoculation (p.i.), and the respiratory tract tissues were subsequently collected. The purpose of the study was to: 1) compare acute, subacute, and chronic pulmonary lesions in PI-3/BVDV versus PI-3 inoculated lambs, and 2) determine cellular distribution of PI-3 and BVDV antigens within the lung by immunohistochemistry. The histopathological lesions were similar in both groups of animals. In acutely infected animals, they consisted of multifocal to coalescing histiocytic and necrosuppurative bronchointerstitial pneumonia. During subacute stages of the infection, histiocytic and suppurative interstitial pneumonia were present accompanied by type II pneumocyte hypertrophy and hyperplasia and bronchiolitis with epithelial cell hyperplasia. Finally, in chronically infected animals, there was mild fibrous interstitial pneumonia with lympho-histiocytic peribronchitis, peribronchiolitis, and perivasculitis. According to immunohistochemistry, PI-3 viral antigen was abundant 3 days p.i., and present within the cytoplasm of the bronchiolar epithelial cells, to a lesser extent in the macrophages and type II pneumocytes, and very rarely in the bronchial epithelial cells. On day 6 p.i., the amount of viral antigen varied among the animals from small amounts in the most severely affected areas to complete absence, while complete viral clearance was noted on day 17 p.i. In conclusion, the simultaneous presence of PI-3 and BVDV viruses in the lung of neonatal lambs does not enhance lesion severity or persistence and distribution of PI-3 antigen.