植生素配方（CTC）對白蝦微孢子蟲 Enterocytozoon hepatopenaei 之功能性與作用機制研究

Abstract

肝胰腺微孢子蟲（Enterocytozoon hepatopenaei, EHP）是蝦類養殖中一種重要的疾病，然而目前尚無有效的治療方法可用於控制蝦類EHP感染。本研究評估了一種由丁香（clove）、百里香（thyme）及肉桂（cinnamon）組成的植物源配方（CTC）對白蝦EHP感染之功能性及作用機制。實驗室試驗結果顯示，CTC可呈劑量依賴性改善EHP感染白蝦之存活率、生長性能、肝胰腺功能障礙及組織病變。隨後，本研究進一步探討CTC抗EHP的作用機制。首先，分析CTC對EHP孢子的影響，結果發現CTC能破壞孢子完整性。此外，CTC可增強蝦類先天性免疫反應，表現為蝦血細胞中總血細胞數（total haemocyte count, THC）、酚氧化酶（phenoloxidase, PO）活性、超氧陰離子（O₂⁻）生成、溶菌酶產生量及吞噬活性之提升。另一方面，透過16S rDNA擴增子定序、培養分析及PCR檢測，結果顯示CTC能降低潛在致病性細菌的豐度。總體而言，本研究結果證實CTC對白蝦EHP感染具有良好的防治效果，並闡明其作用模式，為控制蝦類EHP感染提供了一種新的策略。

Enterocytozoon hepatopenaei (EHP) is a major disease in shrimp farming; however, no effective treatment for EHP in shrimp is currently available. In this study, I assessed the functional and mechanistic effects of a phytogenic formulation, composed of clove, thyme, and cinnamon (CTC), on EHP in whiteleg shrimp. A laboratory study indicated that CTC dose-dependently improved the survival rate, growth performance, hepatopancreatic dysfunction, and lesions in shrimp infected with EHP. Next, I explored the anti-EHP mechanism of CTC. I initially examined the effects of CTC on EHP spores. I found that CTC disrupted spore integrity. Furthermore, CTC enhanced innate immunity as indicated by upregulation of total haemocyte count (THC), phenoloxidase (PO) activity, superoxide anions (O₂⁻) production, lysozyme production, and phagocytic activity in shrimp haemocytes. Similarly, CTC was shown to reduce the abundance of potentially pathogenic bacteria based on 16S rDNA amplicon sequencing, plating assays, and PCR analysis. Overall, the results highlight the effectiveness and mode of action of CTC against EHP in whiteleg shrimp, and thus provide a new strategy for controlling EHP infection in shrimp.