Takahashi K G, Nakamura A, Mori K
Laboratory of Aquacultural Biology, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori Amamiyamachi, Aoba-ku, Sendai, Miyagi, 981-8555, Japan.
J Invertebr Pathol. 2000 Apr;75(3):212-7. doi: 10.1006/jipa.1999.4922.
In order to develop an alternative method to antibiotics for preventing bacillary necrosis in bivalve mollusc larvae, we examined the effects of ovoglobulins (proteins derived from the whites of hens' eggs) on the survival of larvae of the Pacific oyster Crassostrea gigas. The pathogenic Vibrio tubiashii (ATCC 19106) was used to infect larvae of the Pacific oyster. V. tubiashii showed strong pathogenicity to oyster larvae, causing 100% mortality after experimental exposure for 24 h at a concentration of 10(5) cfu (colony-forming units)/ml. In contrast, the addition of ovoglobulins at a concentration of 10 microg/ml to larval oysters, challenged with V. tubiashii at 10(5) cfu/ml, led to a marked increase in larval survival of 96.5% at 24 h after infection. The V. tubiashii culture supernatant was also shown to be pathogenic to larval oysters; however, its pathogenicity was completely inhibited by the addition of 10 microg/ml of ovoglobulins. Larval oysters infected by V. tubiashii showed typical symptoms of bacillary necrosis including anomalous swimming and detachment of cilia and/or vela. In contrast, live larvae were actively motile, and their cilia and vela were not necrotized in the ovoglobulins-added group. The addition of ovoglobulins clearly suppressed the growth of V. tubiashii in gelatin-sea water 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 ovoglobulins almost completely protect larval oysters from V. tubiashii infection by nonbactericidally inhibiting the growth of V. tubiashii without affecting survival of the oysters.
为了开发一种替代抗生素的方法来预防双壳贝类幼虫的细菌性坏死，我们研究了卵球蛋白（从鸡蛋蛋清中提取的蛋白质）对太平洋牡蛎幼虫存活的影响。使用致病性塔氏弧菌（ATCC 19106）感染太平洋牡蛎幼虫。塔氏弧菌对牡蛎幼虫表现出很强的致病性，在浓度为10⁵ cfu（菌落形成单位）/ml的情况下，实验暴露24小时后导致100%的死亡率。相比之下，向受到浓度为10⁵ cfu/ml的塔氏弧菌攻击的牡蛎幼虫中添加浓度为10微克/毫升的卵球蛋白，在感染后24小时幼虫存活率显著提高至96.5%。塔氏弧菌培养上清液也被证明对牡蛎幼虫具有致病性；然而，添加10微克/毫升的卵球蛋白可完全抑制其致病性。受到塔氏弧菌感染的牡蛎幼虫表现出细菌性坏死的典型症状，包括异常游动以及纤毛和/或膜的脱落。相比之下，在添加卵球蛋白的组中，活幼虫活动活跃，其纤毛和膜没有坏死。添加卵球蛋白明显抑制了塔氏弧菌在明胶 - 海水肉汤中的生长，但培养24小时后塔氏弧菌的活菌数并未降至初始剂量水平。本研究结果表明，卵球蛋白通过非杀菌性抑制塔氏弧菌的生长，几乎完全保护牡蛎幼虫免受塔氏弧菌感染，且不影响牡蛎的存活。
