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

在本研究中，作者确定并讨论了巨型太平洋牡蛎，crassostrea gigas的宿主防御过程与保护幼虫坏死的生物对照方法之间的功能相互关系，该方法是由病原性颤动物种引起的幼虫牡蛎的。在许多双壳类软体动物的孵化场中，已经报道了海洋弧菌物种感染通常引起的大幼虫死亡率。感染的幼虫显示出典型的细菌坏死病例包括异常游泳和纤毛和vela的脱离。结果，被认为是由致病性弧菌菌株产生的蛋白酶在杆菌坏死的发病机理中起主要作用。抗生素的使用已被证明是控制这种疾病并改善幼虫牡蛎存活率的有效方法。但是，不建议进行抗生素治疗，因为它会影响培养基水中的细菌菌群，也可能导致R…更具耐药性的致病细菌的表达。因此，为了开发用于预防杆菌坏死的抗生素方法的方法，作者研究了卵巨额球蛋白的作用，卵动蛋白是亨氏蛋白中的一种糖蛋白，并且众所周知可以结合并抑制蛋白质的数量，对蛋白质的数量对巨大的Pacific Oyster的幼虫生存。作者还调查了具有潜在性作为生物控制剂的细菌菌株用于弧菌感染。致病性颤音Tuboshii（ATCC19106）用于感染太平洋牡蛎的幼虫。 V. tuboshii对牡蛎幼虫表现出强烈的致病性，在24小时以10^5 CFU（菌落形成单位）/ml浓度造成100％死亡率Aftar实验暴露。相反，在10^5 cfu/ml时，在10μg/ml的浓度下以10μg/mL的浓度添加卵曲霉蛋白，导致感染后24小时的幼虫存活率显着增加了96.5％。活幼虫积极地运动，其纤毛和vela在卵球蛋白添加的群体中没有被坏死。卵灵球蛋白的添加清楚地抑制了明胶 - 盐水肉汤中V. tubiashii的生长，但是孵育后24小时可存活的V. tubiashii的数量并未降低到初始剂量水平。在这项研究中获得的结果表明，卵曲霉蛋白几乎完全保护了幼虫牡蛎免受非细菌性抑制V. tubiashii的生长而不会影响牡蛎生存的生长的幼虫。较少的