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产业。随着水产养殖规模的扩大，鱼类现在以高种群密度饲养。如果传染性病原体进入农场，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学疗法的效力有限，以及疾病的无症状携带，当受影响的鱼类种群受到压力时，导致疾病爆发。加氏乳球菌感染在日本是一种流行的细菌性疾病。鱼体的粘膜组织构成了巨大的表面积，许多传染性生物通过粘膜组织侵入或定殖，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受体。鞘糖脂（GSL）是细胞质膜的普遍存在的组分。本研究的目的是证明L.garvieae的黄尾GSL的粘附。从肠道粘膜和脑组织中分离纯化的神经节苷脂酶带经薄层层析鉴定，其迁移率与GM_3神经节苷脂标准品相似。用糖苷酶预处理肠道制剂以剂量依赖的方式阻断细菌的粘附，这表明神经节苷脂在黄尾鱼肠道中作为L.garvieae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.