魚用 Edwardsiella tarda 不活化疫苗的開發

Edwardsiella tarda被認為是全世界養殖淡水和海洋魚類的重要細菌病原體之一。E.tarda所引起的病症稱為愛德華氏菌病，其病徵為肛門腫脹、出血、眼球突出、及魚隻解剖上，肝腎明顯看出嚴重的病理症狀。由於E. tarda是細胞內病原體，而目前大多數抗生素藥劑對E. tarda並不是有成效。目前雖有E. tarda之免疫製劑的研發，但尚未有有效可保護魚隻的上市製劑。本實驗的目的是利用海藻酸鈉為包埋材料，包埋不活化E. tarda疫苗用於魚類口服免疫；海藻酸鈉凝膠是一種生物可降解性和生物可相容性的材料，海藻酸鈉凝膠可利用包埋方式於製備可控制釋放抗原之微顆粒疫苗上，在使用上是安全有效的；本研究以乳化的方法製備顆粒，使用含有不同濃度Span 80的植物油，再以改變海藻酸鈉和油相的比例、攪拌速率和攪拌時間來觀察製作出之微顆粒型態。以1.5 %海藻酸鈉、0.05 % Span80及500 rpm之攪拌速度所製備之海藻酸鈉微顆粒具有完整球體外觀、顆粒粒徑分佈平均；在仿腸胃液酸鹼值條件下，微顆粒之釋放效率高達80%以上。未來將可依本研究之結果與經驗，開發商用疫苗。

關鍵字

不活化疫苗；海藻酸鈉微顆粒

並列摘要

Edwardsiella tarda has been recognized as one of the important bacterial pathogens to the cultured freshwater and marine fish worldwide. Infections with this bacterium have resulted in major economic losses in Taiwan aquaculture industry. Infection with E. tarda often leads to the development of a systematic disease called edwardsiellosis, characterized by symptoms of anal swelling, hemorrhagic, exophthalmia, liver and kidney severe lesions of internal organs. Since E. tarda is an intracellular pathogen, most antibiotics are not effective to treat edwardsiellosis. Although development of immunizing agents has being studied, effective products are not currently available for use in fish protection from edwardsiellosis. Recent decades, biodegradable and biocompatible alginate gels have been used as safe, potent adjuvants or delivery systems to encapsulate antigens for preparing controlled-release microparticle vaccines. In the study, therefore, sodium alginate was used as an encapsulation material to entrap inactivated E. tarda for producing a microparticle vaccine against edwardsiellosis in fish; The particles were prepared through an emulsion-based methodology employing by homogenizing vegetable oils containing different surfactant Span 80, adjusting the ratios of sodium alginate and oil phase at different homogenization speed and time. The sodium alginate microparticles could be prepared by utilizing 1.5 % sodium alginate and 0.05 % Span 80 at 500 rpm of homogenization speed. These parameters have been appropriate for spherical morphology, particle size distribution and antigen release effect. Based on the in vitro release test, the release efficiency of microparticles could reach up to 80%.