Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/13731
標題: 豬萎縮性鼻炎重組次單位巴氏德桿菌毒素疫苗之研發與免疫效力評估
The development and efficacy of recombinant subunit Pasteurella multocida toxin vaccines against swine progressive atrophic rhinitis
作者: 廖志明
Laio, Chih-Ming
關鍵字: progressive atrophic rhinitis
豬萎縮性鼻炎
Pasteurella multocida toxin
subunit vaccine
巴氏得桿菌毒素
次單位疫苗
出版社: 獸醫學系
摘要: 在本研究中共成功構築與表現三種重組次單位Pasteurella multocida toxin (rsPMT) 毒素蛋白,而此三種rsPMT均保有與authentic PMT部分相同之抗原性,且對Vero細胞、天竺鼠與小鼠均不具生物毒性。小鼠經免疫rsPMT後其脾臟中可誘發大量辨識PMT之特異性抗體分泌細胞 (antibody-secreting cells; ASCs) 的增殖,也可激起明顯之細胞性免疫反應,免疫小鼠亦能耐過致死劑量authentic PMT的攻擊。此外,豬隻經rsPMT免疫後,以authentic PMT攻毒或應用同源性抗原的再刺激後,脾臟中ASCs數量亦呈顯著性之增加,並可測得高力價的中和抗體與明顯之淋巴細胞增殖反應。這些結果均顯示rsPMT能有效誘導豬隻產生中和authentic PMT毒素的免疫反應,且其保護效力更明顯優於傳統的類毒素疫苗。此外,懷孕母豬經免疫後於初乳中也可測得高保護力價之中和抗體 (1:80-1:101),而其新生仔豬以5倍致死劑量之毒素攻擊後,其存活率 (60%) 更明顯優於傳統類毒素疫苗之免疫組 (0%),進一步以低於致死劑量之毒素攻擊來比較仔豬的生長性能時,rsPMT免疫組仔豬除有顯著的降低PMT毒素的生長抑制現象外,並無呈現典型的臨床病徵與病理變化。 於田間試驗方面,共選取15個一貫式養豬場以母豬施用rsPMT不活化菌苗進行免疫效益之評估,結果顯示平均有78.3%以上的經產母豬皆可被誘發整齊且平均之高保護性中和抗體力價,而平均亦有39.4%的新母豬其中和抗體仍可揚升至具有保護性之1:16以上。此外,選取一嚴重感染場進行免疫效益評估,施用前所有母豬均無法被檢測出具有中和PMT毒素之抗體力價,且嚴重感染的豬隻均呈現嗤鼻、流鼻血甚至鼻吻部明顯變形等臨床症狀;但經全場施用疫苗後,母豬產生中和抗體之轉陽率為100%,同時在肉豬群所呈現萎縮性鼻炎的疫情亦明顯獲得控制及改善,且平均到達上市體重之飼養期則縮短14天,更顯示疫苗良好的免疫保護性與經濟效益。 本研究亦嘗試探討豬假性狂犬病Pseudorabies (PR)與萎縮性鼻炎(PAR)雙價疫苗之免疫效益評估,除PR/rsPMT-PAR雙價疫苗在肉豬具有良好之安全性及免疫保護效力外,母豬更可產生足夠之移行抗體以保護其新生仔豬免於萎縮性鼻炎與PR之雙重感染。而免疫豬隻不論以PMT毒素及PR病毒攻毒後,均無呈現生長抑制與任何的典型病變。綜合以上研究結果顯示,不論單價重組次單位PMT毒素疫苗與PR/rsPMT-PAR雙價疫苗於仔豬與懷孕母豬均具有良好之安全性與免疫效益,除能大幅減少因多次免疫所造成之緊迫與降低疫苗成本外,更提供一較佳之防疫措施以有效控制豬隻之複合性疾病感染。
In this study, three recombinant subunit Pasteurella multocida toxins (rsPMTs) were constructed and expressed successfully. These rsPMTs were non-toxic both in mice and swine and could induce PMT-specific antibody-secreting cells and cellular immunity in spleen. The rsPMT-immunized mice could survive the lethal dose challenge of authentic PMT, and the PMT-specific antibody-secreting cells (ASCs) increased significantly. In addition, immunized piglets generated higher neutralizing antibody titers after authentic PMT challenge or homologous antigen boost. Furthermore, pregnant sows immunized with rsPMT exhibited higher levels of maternal antibodies in colostrum than did those immunized with a conventional toxoid vaccine. Offspring from rsPMT vaccinated sows had better survival rate after challenge with a 5-fold lethal dose of authentic PMT and had better growth performance after challenge with a sublethal dose of toxin. A total of 542 sows from 15 conventional farms were selected to evaluate the vaccine efficacy in field trials. The results indicated that 78.3% of multipara sows could generate higher protective maternal antibody titers than those with less parity. Moreover, there were 39.4% of gilts could still mount good protective antibody titer with 1:16 or higher. Furthermore, a conventional farm which had suffered from severe progressive atrophic rhinitis (PAR) was selected to estimate the vaccine efficacy. Twelve months after vaccination, the clinical symptoms of PAR were significantly decreased and the growth performance of fattening pigs improved remarkably as the period of gaining sufficient body weight for marketing was decreased by 14 days. These results demonstrated that a non-toxic AR-rsPMT is a potential candidate for the development of new generation vaccines against PAR in pigs.
URI: http://hdl.handle.net/11455/13731
Appears in Collections:獸醫學系所

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