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標題: 豬周邊血液吞噬細胞與沙氏桿菌致病性之探討
The Role of Porcine Peripheral Blood Phagocytes on The Pathogenicity of Salmonella spp.
作者: 洪健哲
關鍵字: Salmonella
Respiratory Burst
Classic Swine Fever
出版社: 獸醫病理學研究所
摘要: 沙氏桿菌症為豬隻嚴重且最常見之細菌性疾病,主要病原為S. choleraesuis與S. typhimurium,並常造成豬隻全身性敗血症及腸炎。為深入探討沙氏桿菌形成敗血症之相關機制,本實驗利用流式細胞儀技術,嘗試建立一全血模式分析法,比較此二種沙氏桿菌感染豬隻周邊血液吞噬細胞與誘導吞噬細胞respiratory burst能力之差異。結果顯示S. choleraesuis不論於感染嗜中性球或單核球之能力皆較S. typhimurium為高,但被吞噬後反而不及S. typhimurium誘導嗜中性球產生respiratory burst之強度。此外,現場上豬之沙氏桿菌症多發生於保育期至肥育前期豬隻,且多數病例為S. choleraesuis 所引起,本實驗亦針對S. choleraesuis與S. typhimurium感染不同年齡層豬隻之周邊血液吞噬細胞吞噬及誘導respiratory burst能力進行比較。結果顯示在5週齡及8週齡健康豬隻S. choleraesuis有較強之的感染周邊血液吞噬細胞之能力,且二菌種間約有2倍左右之差異,而於3週齡及12週齡健康豬隻則無明顯之區別。但在誘導吞噬細胞產生respiratory burst方面,則於各年齡豬隻結果均相似,結果顯示S. typhimurium 較S. choleraesuis容易誘導嗜中性球產生respiratory burst反應,且二者約有1.75-2.17倍左右之差異,但在誘導單核球之能力上則無明顯差異。 此外,現場上常見豬瘟併發沙氏桿菌症之病例,為進一步探討豬瘟感染後宿主防禦細胞對沙氏桿菌吞噬能力與誘導respiratory burst之影響,本實驗利用豬瘟病毒(Ping-Tnug strain)以人工感染方式,評估其對宿主防禦細胞吞噬與清除沙氏桿菌能力之影響。結果顯示,在病毒感染後第3天起白血球總數上呈現明顯減少的趨勢,並於感染後第18-21天白血球總數僅存約正常豬隻的20-30%,而數目減少之細胞族群則以淋巴球及單核球為主。而在吞噬功能的影響上,病毒感染後血液吞噬細胞吞噬S. choleraesuis及S. typhimurium之能力明顯降低,其中單核球及嗜中性球分別於感染後第3天與第7天其吞噬能力開始呈現顯著的下降,而於感染後的18-21天吞噬細胞吞噬S. choleraesuis及S. typhimurium的能力僅存正常豬隻吞噬能力的20-30%。在respiratoy burst之影響方面,當感染3-7天後吞噬細胞其respiratoy burst能力下降至正常值之70-80%,而於第10-14 天雖有短暫回昇之現象,但於第18-21天respiratoy burst能力僅存正常值的10-30%。故由上述結果推論,豬瘟感染後除了會造成白血球總數迅速減少之外,亦會導致血液中各種吞噬細胞無法有效清除外來病原,且其吞噬後之殺菌能力亦明顯降低,而致使二次性沙氏桿菌感染的機會大幅增加。
Salmonellosis is among the most important bacterial diseases in swine worldwide, and the causative agents S. choleraesuis and S. typhimurium can induce systemic septicemia and gastroenteritis. The purpose of this study is to evaluate the phagocytic activity and respiratory burst in peripheral blood phagocytes (PBP) against S. choleraesuis and S. typhimurium via a whole blood model using flow cytometric analysis. The results demonstrated that S. choleraesuis possessed a higher invasive activity and induced less respiratory burst reaction than S. typhimurium in neutrophils and monocytes. Moreover, the age variation were also analyzed and the invasive activity of S. choleraesuis showed 2 fold higher than S. thyphimurim in 5-week and 8-week old pigs, but there were no differences in 3-week and 12-week old pigs. The respiratory burst reaction induced by S. choleraesuis in neutrophils was 1.75-2.17 fold less than S. typhimurium, but no significant variation was noticed in monocyte. That results revealed thst S. choleraesuis has better ability to survive in phagocytic cells during infection and this may explain why S. choleraesuis always dominate in cultivated rate from outbreak cases in the field. In addition, the outbreak of classical swine fever virus (CSFV) infection is almost accompanied with salmonellosis in the field, but the mechanism and relationship between both diseases still remain unclear. The new invaded strain (Ping-Tung isolate) of CSFV was used to investigate the influence of CSFV on the clearance activity of PBP against Salmonella. The results verified that the total amounts of peripheral blood leukocytes decreased significantly to 20-30% in comparison with the control group, and both lymphocytes and monocytes were the major target cells during CSFV infection. Moreover, the phagocytic ability of neutrophils and monocytes against S. choleraesuis and S. typhimurium during CSFV infection declined at 3 and 7 days post infection (DPI) respectively, and even dropped to 20-30% at 18-21 DPI. In addition, the respiratory burst of PBP was dropped to 70-80% at 3-7 DPI and slightly recovered at 10-14 DPI, however it dramatically dropped to 10-30% at 18-21 DPI. These results suggest that CSFV infection not only induces leucopenia but also impairs the phagocytic and respiratory burst activity of PBP against Salmonella spp. in swine.
Appears in Collections:獸醫病理生物學所



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