棘阿米巴是一種在水體內自由營生的寄生蟲，主要會出現在河川、水庫、湖泊、溫泉等水域，原蟲在感染後會對人類造成棘阿米巴角膜炎或者是肉芽腫性阿米巴腦炎。目前為止，除了接種到動物身上測試，還沒有其他方法可以去判斷這些環境中的蟲株是否會對人類造成疾病。為了找出可能的方法去鑑定棘阿米巴蟲株的毒性，我們從台灣各地水庫、河川等地收集了 16 株環境蟲株。為避免其他
環境因子影響，我們嘗試將這些蟲株從充滿細菌、黴菌的環境水體中分離出來，至今共有 16 株已成功分離至無菌培養。為鑑定這些蟲株的毒性，我們建立細胞病變效應測試嘗試量化蟲株對細胞的破壞程度，進而測試並統計所收集的各蟲株對細胞的毒力。 在本研究將蟲株的毒力程度與樣本採集的時間與地點等流行病學資訊交叉比對後 ，發現在秋季所採集到的環境蟲株相較其他蟲株對細胞的破壞力較強。然而，若是在每次採集水體後，期望進一步鑑定原蟲之致病力，都要從分離、純化培養棘阿米巴蟲株到 CPE 鑑定，太過於耗時。因此，本研究希望進一步嘗試尋找與致病力相關的生物標記進行基因分型，以求能更快速的鑑定棘阿米巴的致病性強弱。我們以毒力強弱不等的各蟲株之 M20/M25/M40 胺肽酶序列為目標進行定序分析，再根據基因序列變異區域進行型別分析。結果顯示：蟲株
M20/M25/M40 胺肽酶序列變異區域與蟲株對細胞的破壞毒力強弱並無絕對相關性。 本研究成功建立棘阿米巴分離蟲株對細胞致病性的鑑定技術，並完成所收集純化的台灣本土臨床及環境分離株的毒力進行量化。雖然目前的各基因分型方式仍皆無法與蟲株致病性連結，本研究成果仍可望作為未來持續前進的重要基礎。

For an accurate investigation of the virulence variability among the Acanthamoeba environmental isolates in Taiwan, we established a cytopathic effect assay (CPE) and a
new set of differential genotypes, which were according to a potential virulence factor, Aminopeptidase M20/M25/M40 (ACA1_264610). In this study, we successfully
identified and quantified the cytopathogenicity of the clinical and environmental Acanthamoeba isolates. The present study provides novel epidemiological information but the isolates do not exhibit significant virulent shifts in Aminopeptidase
M20/M25/M40 genotyping.

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