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A Functional Reciprocal Relationship Between the Host Defense Mechanisms of Oysters and the Bio-control Methods for Protection of Bacillary Necrosis of Larval Oysters Caused by Pathogenic Vibrio Species

牡蛎宿主防御机制与病原弧菌引起的牡蛎幼体杆菌性坏死生物防治方法之间的功能相互关系

基本信息

批准号：
13660176
负责人：
TAKAHASHI Keisuke
金额：
$ 2.18万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

In the present study, the author determined and discussed a functional reciprocal relationship between the host defense process of the giant Pacific oyster, Crassostrea gigas, and the bio-control methods for protection of bacillary necrosis of larval oysters caused by pathogenic Vibrio species. In many hatcheries of bivalve molluscs, mass larval mortalities often induced by marine Vibrio species infections have been reported. Infected larvae showed typical cases of bacillary necrosis including anomalous swimming and the detachment of cilia and vela. As a result, it is considered that proteases produced by the pathogenic Vibrio strains play a major role in the pathogenesis of bacillary necrosis. The use of antibiotics has been shown to be an effective method for controlling this disease and improving the survival of larval oysters. However, antibiotic treatment is not recommended because it is can affect bacterial flora in the culture sea water and can also result in the expression of r … More esistant pathogenic bacteria. Therefore, in order to develop altenative methods to antibiotics for preventing bacillary necrosis, the author examined the effects of ovomacroglobulin, which is a glycoprotein in the hen's egg whites and is well known to bind and inhibit strongly the number of proteases, on the larval survival of the giant Paciftc oyster. The author also investigated the use of bacterial strains that have potentiality as bio-control agents for Vibrio infection. The pathogenic Vibrio tubiashii (ATCC19106) was used to infect larvae of the Pacific oyster. V. tubiashii showed strong pathogenicity to oyster larvae, causing 100 % mortality aftar experimental exposure for 24 h at a concentration of 10^5 cfu (colony-forming units)/ml. In contrast, the addition of ovomacroglobulin at a concentration of 10 μg/ml to larval oysters, challenged with V. tubiashii at 10^5 cfu/ml, led to a marked increase in larval survivel of 96.5% at 24 h after infection. Live larvae were actively motile, and their cilia and vela were not necrotized in the ovomacroglobulin-added group. The addition of ovomacroglobulin clearly suppressed the growth of V. tubiashii in gelatin-seawater broth, but the number of viable V. tubiashii 24 h after incubation did not decrease to the initial dose level. Findings obtained in this study indicate that ovomacroglobulin almost completely protect larval oysters from V. tubiashii infection by non-bactericidally inhibiting the growth of V. tubiashii without affecting the survival of the oysters. Less

本文探讨了太平洋牡蛎（Crassostrea gigas）的宿主防御过程与致病弧菌引起的牡蛎幼虫细菌性坏死的生物防治方法之间的功能性相互关系。在许多双壳类软体动物的孵化场，大量的幼虫死亡往往引起海洋弧菌感染的报道。感染后的幼虫出现典型的细菌性坏死，包括异常游动和纤毛、帆的脱落。因此，人们认为致病性弧菌菌株产生的蛋白酶在杆菌坏死的发病机制中发挥着重要作用。使用抗生素已被证明是控制这种疾病和提高牡蛎幼虫存活率的有效方法。然而，抗生素处理是不推荐的，因为它会影响养殖海水中的细菌植物群，也会导致r ...更多信息耐药致病菌。因此，为了开发抗生素的替代方法来预防细菌坏死，作者研究了卵巨球蛋白（ovomacroglobulin）对巨型太平洋牡蛎幼虫存活的影响。卵巨球蛋白是鸡蛋蛋白中的一种糖蛋白，众所周知，它能强烈地结合和抑制蛋白酶的数量。作者还研究了具有作为弧菌感染的生物控制剂的潜力的细菌菌株的使用。用致病性管氏弧菌（Vibrio tubiashii，ATCC 19106）感染太平洋牡蛎幼体。管氏弧菌对牡蛎幼虫具有较强的致病性，在10^5 cfu/ml浓度下，24 h后死亡率为100%。与此相反，在用10^5 cfu/ml管氏弧菌攻击的牡蛎幼虫中加入浓度为10 μg/ml的卵巨球蛋白，导致感染后24 h的幼虫存活率显著增加，为96.5%。活幼虫活动活跃，其纤毛和帆在卵巨球蛋白添加组中没有坏死。卵巨球蛋白的添加明显抑制了管氏弧菌在明胶-海水肉汤中的生长，但孵育后24 h活管氏弧菌的数量并未降低至初始剂量水平。本研究结果表明，卵巨球蛋白几乎完全保护牡蛎幼虫免受管氏弧菌的感染，通过非致死性地抑制管氏弧菌的生长，而不影响牡蛎的存活。少