The Role of Viral Infection on the Development of Porcine Proliferative and Necrotizing Pneumonia-Like Lesions: PCV2, PRRSV, SIV, and PPV
Date Issued
2005
Date
2005
Author(s)
Lee, Yu-Tsung
DOI
zh-TW
Abstract
In the late 1980s, a new type of porcine pneumonia of unknown etiology called proliferative and necrotizing pneumonia (PNP) was described in Quebec, Canada. Histologically, it was characterized by a lymphohistiocytic interstitial pneumonia with a marked proliferation of type 2 pneumocytes and many coagulates of necrotic cells in the alveoli. Occasionally, hyaline membranes and bronchiolar necrosis were also observed. Between 2002 and 2003, 275 cases were collected from pig farms of Taiwan. The main clinical signs of these cases were tachypnoea, dyspnea, and abdominal respiration. Histopathological characteristic lesions of proliferative and necrotizing pneumonia (PNP) were found in 50 cases (18%). Single viral infection was only detected in 1 case (2%), whereas in other 49 cases (98%), a combination of viral and bacterial infection was noted. Polymerase chain reaction (PCR) was used for the detection of porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae, and the frequency of positive results were 50 (100%), 6 (12%) and 11 (22%) cases, respectively. The infection of Salmonella sp. was presented in 12 cases (24%) by bacterial isolation. By in-situ hybridization (ISH), PCV2 signals were chiefly distributed in interstitial and necrotic lesions, and the positive signals could be found in macrophages-like cells and necrotic debris. PRRSV signals were mainly located at interstitial lesions and alveolar wall, and the positive signals could be found in macrophages-like cells and epithelial cells of alveoli. Swine influenza virus (SIV) could be found in interstitial and necrotizing lesions, and the signals could be found in macrophages-like cells, and epithelial cells of terminal bronchiole and alveoli. By immunohistochemistry (IHC), porcine parvovirus (PPV) signals were mainly distributed in interstitial and necrotic lesions, and the positive signals could be found in macrophages-like cells and epithelial cells of terminal bronchiole and alveoli. The ISH results revealed that the signals of PCV2 and SIV were profoundly present in the necrotic and interstitial lesions, but SIV signals were weaker and less often. The signals of PRRSV were scattered and related to the alveolar wall of interstitial lesions. The IHC results showed the signals of PPV were present in the necrotic and interstitial lesions, the signals could occasionally be found in suppurative lesions of the terminal bronchiole. In conclusion, PNP lesions maybe induced by the co-infection of several pathogens, especially PCV2 and PPV. Additionally, this is the first study demonstrates a high prevalence of PPV infection in Taiwan.
Subjects
豬增生性壞死性肺炎
第二型豬環狀病毒
豬生殖與呼吸道綜合症病毒
豬流行性感冒病毒
豬小病毒
Porcine Proliferative and Necrotizing Pneumonia
Porcine Circovirus type 2
Porcine Reproductive and Respiratory Syndrome Virus
Swine Influenza Virus
Porcine Parvovirus
Type
thesis
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