Cytokine expression in the lymph nodes and lungs of porcine reproductive and respiratory syndrome virus-infected pigs by in situ hybridization
| Autor: | Pi-Hung Liao, 廖碧虹 |
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| Rok vydání: | 2000 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 88 The aim of this study was to determine the relationship between the organ distribution of porcine reproductive and respiratory virus ( PRRSV ) and the cytokine IL-1, IL-2, TNF-, and IFN- mRNA expression in two experimental PRRSV-infected pig groups by in situ hybridization. Seven 2-day-old PRRSV-free and 35 4 to 5-week-old, SPF pigs were randomly allocated to the PRRSV-infected group/control group at ratio 6/1 and 18/17, respectively. The PRRSV-infected and control animals were intranasally inoculated with 0.5 ml 105 PRRSV TCID50 /ml or culture medium per nostril. Two-day-old control and PRRSV-infected pigs were euthanatized at 0 and at 1, 3, 7 days post infection ( DPI ), respectively. Four to 5-week-old control pigs and PRRSV-infected pigs were euthanatized at 0, 3, 7, 14 and 21DPI, and at 1, 3, 7, 14 and 21 DPI, respectively. The virus RNA probe for in situ hybridization was a 433 bp, DIG-labeled fragment corresponding to the open reading frame 7 of the PRRSV. The cytokine RNA probes for in situ hybridization were DIG-labeled with a size of IL-1480bpIL-2 401bpTNF-340bpandIFN-367bpIn the 2-day-old pigs specific viral signals were detected in the lungs and the various lymph nodes, including bronchialprescapularcervicalgastric, and mesenteric lymph nodes. In the lungs, the number of PRRSV-infected cells increased with time; however, it appeared to be unrelated in the lymph nodes. Specific TNF- and IFN- signals increased with the raising number of PRRSV-infected cells in the prescapular gastric, and mesenteric lymph nodes, nevertheless, there was no spatial location relationship between the PRRSV-infected and cytokine -expressing cells. All of the PRRSV and cytokine signals in 4 to 5-week-old pigs were weaker than those of the neonatal group. These signals were scattered in the interstitial lesions of the lung. In bronchial lymph node, the positive PRRSV-infected cells reached the highest numbers at 3 DPI, and decreased with time. In the meantime, similar trend was present in TNF-and IFN- mRNA-expressing cells. PRRSV and IFN- positive signals were detected in the intestinal mucosa and submucosa at 14 and 21 DPI. Positive signal-exhibiting cells morphologically resembled alveolar and interstitial macrophages and other mononuclear inflammatory cells in the lungs; and resembled macrophages, dendritic cells, and other mononuclear cells in the medullay and peripheral germinal center of the lymph nodes. The results suggest: 1) in the neonatal pig group, there was a similar trend of change number between viral-infected and TNF-and IFN-mRNA expressing-cells, but there was no locational relationship between virus-infected and cytokine-expressing cells; 2) in the 4 to 5-week-old pig group, cytokine mRNA expressing-cells were less than those in the neonatal group, and there were no particular positional correlation among PRRSV-infected cells, cytokine-expressing cells, and lesion formation; 3) virus shedding from alimentary tract was possible at the late infection stage. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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