近年來許多研究表明益生菌可作為一種新策略來降低病毒或過敏性疾病發生的風險,而芽孢桿菌作為潛力益生菌具有獨特的內孢子結構,使在腸胃道或飼料加工的惡劣環境下表現出較好的生存能力,且適用於健康的促進劑。故本研究選用分離自實驗室且具益生菌潛力的液化澱粉芽孢桿菌LN(Bacillus amyloliquefaciens LN)、貝萊斯芽孢桿菌AC(B. velezensis AC)與地衣芽孢桿菌CK1(B. licheniformis CK1)作為研究對象,評估其抗病毒與抗過敏功效。在抗病毒試驗中,將LN、AC及CK1之胞內液及細胞壁預處理Vero細胞後測定抗豬流行性下痢病毒(porcine epidemic diarrhea virus, PEDV)的活性,可得LN及AC的菌株萃取物皆表現抗病毒能力且以LN效果最好;進一步探討抗病毒機制後,儘管兩菌株萃取物無法有效上調抗病毒基因的表現,但促發炎細胞激素及病毒核殼蛋白的RNA基因表現皆於感染後的48小時顯著下降;此外,菌株萃取物與PEDV之直接相互作用試驗結果則表明彼此不具影響性。在抗過敏試驗中,以注射花生蛋白萃取物的方式誘導C3H/HeOuJ小鼠致敏並在預防及治療模式下管餵CK1(10^10 CFU/kg體重),發現致敏小鼠在餵食CK1後可減輕過敏性症狀並抑制IgE介導的過敏反應;腸道組織學分析顯示CK1的餵食明顯減少腸黏膜肥大細胞的數量並恢復因致敏而造成的腸黏膜損傷;此外,致敏小鼠在餵食CK1後其腸道菌群中Clostridia的豐度明顯增加。總結來說,LN和AC具抗PEDV活性而有潛力作為抗病毒之飼料添加物,期望有效預防動物病毒性疾病的發生,而CK1具有減緩花生過敏之功效,未來希望能應用於食品或寵物食品添加劑。
In recent years, many studies have provided a new strategy of using probiotics to lower the risk of viral or allergic diseases. Bacillus strains as potential probiotics exhibited the unique endospore structure, which showed better survivability in the harsh environment of the gastrointestinal tract or feed processing, so that made Bacillus strains more suitable for health-promoting formulations. Therefore, this study aimed to evaluate the antiviral and antiallergic effects of Bacillus strains with probiotic potential, including B. amyloliquefaciens LN, B. velezensis AC and B. licheniformis CK1. In the antiviral assay, the intracellular extracts and cell wall fractions of LN, AC and CK1 were used to test the anti-porcine epidemic diarrhea virus (PEDV) activity in Vero cell model. Among them, both strain extracts of LN and AC exhibited the anti-PEDV activity, and especially LN showed the best effect. After exploring the antiviral mechanism, although the strain extracts could not up-regulate the expression of antiviral genes, the proinflammatory genes and PEDV nucleocapsid protein-coding RNA showed significant down-regulation at 48 hours post-infection. Besides, the direct interaction assay between strain extracts and PEDV showed no impact on each other. In the antiallergic assay, C3H/HeOuJ mice were orally administrated with CK1 (10^10 CFU/mL/kg body weight) in the prevention and treatment modes and injected with peanut (PE) to induce the sensitization. About the results, oral administration of CK1 could improve the severe anaphylactic symptoms in PE-sensitized mice, and also effectively inhibit the IgE-mediated allergic response. In the histology of the small intestine, the numbers of mucosal mast cells in the CK1-administrated mice were significantly declined; in addition, CK1 also repaired the mucosal damage caused by sensitization. The study of gut microbiota showed the higher abundance of Clostridia in sensitized mice after oral administration of CK1. In conclusion, LN and AC with anti-PEDV activity are promising candidates to be used as antiviral feed additives, which are expected to effectively prevent the occurrence of animal viral disease; moreover, CK1 with antiallergic effect is expected to be used in food or pet food additives in the future.
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