Martínez Juan Luis, Casado Alín, Enríquez Ricardo
Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo, c/ Catedrático Rodrigo Uría s/n, 33071 Oviedo, Spain.
Dis Aquat Organ. 2004 Apr 21;59(1):79-84. doi: 10.3354/dao059079.
Infections caused by Flavobacterium psychrophilum include 'bacterial coldwater disease' (BCWD) and 'rainbow trout fry syndrome' (RTFS), which are severe diseases that can cause high mortality and significant losses in hatchery-reared salmonids worldwide. Usually, these conditions start with necrosis along the edge of the fins. As the infection progresses, both the fish surface and the internal organs can be involved. The aetiological agent produces a Ca-dependent protease that can be responsible for some of the pathogenic responses, although the precise nature of the response remains to be elucidated. Atlantic salmon Salmo salar were experimentally infected by F. psychrophilum in order to investigate the bacterial invasion in the fin tissues by scanning electron microscopy. The images showed numerous bacteria embedded in the mucous layer when this remained on the tegument. In other zones without mucus, it was observed that bacteria were present on the axis of fin rays, but not on the epidermal surface. The material on these axes was largely eroded by tubular boreholes, and bacterial rods could be seen in these perforations. EDX (Energy Dispersive X-ray) microanalysis of the axis of the fin rays showed significant amounts of P and Ca, revealing the ossification of the ray axis. The protease activity could explain the formation of the tubular boreholes, allowing the bacteria the necessary Ca for the activation of the enzyme. The erosion pattern suggests that the gliding motility of F. psychrophilum could be involved in this burrowing ability.
嗜冷黄杆菌引起的感染包括“细菌性冷水病”（BCWD）和“虹鳟鱼苗综合征”（RTFS），这些都是严重的疾病，可导致全球孵化场养殖的鲑科鱼类高死亡率和重大损失。通常，这些病症始于鳍边缘的坏死。随着感染的进展，鱼的体表和内脏都会受到影响。病原体产生一种钙依赖性蛋白酶，虽然其反应的确切性质尚待阐明，但这种蛋白酶可能是一些致病反应的原因。为了通过扫描电子显微镜研究鳍组织中的细菌入侵情况，对大西洋鲑进行了嗜冷黄杆菌的实验感染。图像显示，当黏液层留在体表时，有大量细菌嵌入其中。在其他没有黏液的区域，观察到细菌存在于鳍条轴上，但不在表皮表面。这些轴上的物质大部分被管状钻孔侵蚀，在这些穿孔中可以看到杆菌。对鳍条轴进行的能量色散X射线（EDX）微分析显示，含有大量的磷和钙，表明鳍条轴发生了骨化。蛋白酶活性可以解释管状钻孔的形成，为细菌提供激活该酶所需的钙。侵蚀模式表明，嗜冷黄杆菌的滑行运动可能与这种挖掘能力有关。
