Innate immunity and protective immune responses in yellowtail induced by liposome-type Lactococcus garvieae vaccine

近几十年来，集约化养鱼已成为一个关键行业。随着水产养殖规模的不断扩大，鱼类现在是在高种群密度下养殖的。如果将传染病病原体引入养殖场，就会发生大规模死亡，造成巨大的经济损失。难以控制疾病的原因是化疗的效果有限，以及疾病的无症状传播，当受影响的鱼类种群受到压力时，会导致疾病暴发。黄尾鱼乳球菌感染是日本的一种流行细菌性疾病。鱼体内的粘膜组织构成了一个巨大的表面积，许多感染性生物通过粘膜组织入侵或定居，特别是肠道。这些病原体将细胞表面的碳水化合物结构识别为结合的受体。鞘糖脂(GSL)是细胞质膜中普遍存在的成分。本研究旨在证明加维氏乳杆菌对黄尾鱼GSL的粘附性。薄层层析结果显示，加氏乳球菌附着在从肠粘膜和脑组织中纯化的神经节苷脂上，其迁移率与GM_3神经节苷脂标准品相似。用糖苷酶处理肠道制剂可剂量依赖性地阻断细菌的黏附，这表明神经节苷脂在黄尾肠道中是加维氏乳杆菌的结合受体。

Intensive fish farming has become a key industry in recent decades. With the increasing scale of aquaculture, fish are now reared at high population densities. Mass mortality occurs if infectious agents are introduced into the farm, causing great financial loss. Difficulty in control of disease arises from the limited effectiveness of chemotherapy, and from asymptomatic carriage of the disease, leading to outbreaks of disease when affected fish stocks are stressed. Lactococcus garvieae infection in the yellowtail is a prevalent bacterial disease in Japan. The mucosal tissues of the body of fish constitute an enormous surface area, and many infectious organisms invade through or colonise mucosal tissues, especially the intestinal tract. These pathogens recognize the carbohydrate structure on the surface of cells as a receptor for binding. Glycosphingolipids (GSL) are ubiquitous components of the plasma membrane of cells. The present study was undertaken to demonstrate the adherence of L.garvieae to GSL of the yellowtail. Lactococcus garvieae adhered to ganglioside bands purified from the intestinal mucous membrane and brain having similar mobility to GM_3 ganglioside standard, according to thin layer chromatography. Adherence of the bacteria was blocked by pretreatment of the intestinal tract preparation with glycosidase in a dose-dependent manner, implying indicating that ganglioside acts as a binding receptor of L.garvieae in the yellowtail intestinal tract.