芽囊原蟲為一種廣泛寄生於人類與動物腸道內的真核單細胞原蟲，感染人類的芽囊原蟲共計9個亞型，糞口傳播為主要的傳播途徑，好發於熱帶及亞熱帶地區。感染人芽囊原蟲的患者大多無明顯徵狀，少部分的臨床症狀包括腹痛、腹瀉、噁心、嘔吐以及近幾年發現與大腸急躁症的發生有關。半胱胺酸蛋白酶廣泛存在於植物與動物體內，參與細胞凋亡等生化反應。然而，近幾年發現，半胱胺酸蛋白酶對於原蟲類寄生蟲扮演重要的角色，功能包括對於宿主的免疫逃避或調節、細胞自噬、酶活化、細胞或組織的入侵等。有關人芽囊原蟲對宿主造成致病的研究中，發現其透過半胱胺酸蛋白酶降解宿主細胞分泌的IgA，進而使宿主易感;部分研究認為不同蟲株之間的毒力差異可能與半胱胺酸蛋白酶活性有關。
根據本實驗室先前研究結果發現，人芽囊原蟲ST7型B蟲株之半胱胺酸蛋白酶1（CP1）存在於不同亞型間，如ST1、ST3及ST7型等的基因組中。基於目前對於人芽囊原蟲病的診斷存在交叉反應且過程繁複，如需抽取糞便DNA等，因此本論文擬著手開發新的診斷方式–以CP1作為分子及免疫診斷。此外，由於CP1蛋白的活性及對宿主的致病性尚未清楚，因此也透過CP1多株抗體中和蟲體內源性CP1蛋白的方式探討CP1蛋白是否為人芽囊原蟲毒力因子之一。結果顯示，利用CP1作為分子與免疫診斷的標的基因具有高專一性及靈敏性。惟CP1多株抗體會與大腸桿菌勝任細胞之內源性蛋白產生交叉反應，因此，若要開發為最終的免疫診斷，則尚需更多的相關技術進行製備，如調整抗體吸附反應條件或開發單株抗體等，以排除可能造成的偽陽性結果。此外，抗體中和蟲體內源性CP1蛋白的細胞病變實驗中發現，CP1能參與人芽囊原蟲對宿主細胞的致病作用，亦可成為多數毒力因子之一。

Previously, we found that the cysteine protease 1 (CP1) commonly existed among different subtypes of B. hominis, such as 1, 3 and 7. Here, we tested the specificity and sensitivity of CP1 primer, and the results showed that CP1 has the potential to become a new molecular diagnostic method. In addition, we found that CP1 has the potential to become an immunodiagnosis by testing the specificity and sensitivity of CP1 polyclonal antibody. Therefore, in order to develop the final immunodiagnosis, more relevant techniques are needed for preparation, such as absorption experiment or monoclonal antibody, to improve the accuracy of immunodiagnosis. Finally, we found that the CP1 protein of B. hominis can participate in the cytopathic effect of host cells, suggesting that CP1 may be one of the virulence factors of B. hominis.

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