Jørgensen Thomas R, Larsen Thomas B, Jørgensen Louise G, Bresciani José, Kania Per W, Buchmann Kurt
Department of Veterinary Pathobiology, Laboratory of Fish Diseases, The Royal Veterinary and Agricultural University, Stigbøjlen 7, Frederiksberg C, Denmark.
Dis Aquat Organ. 2007 Jan 18;73(3):235-44. doi: 10.3354/dao073235.
Gyrodactylus salaris was isolated from rainbow trout in a Danish freshwater trout farm, and a laboratory population of this particular parasite form was established on rainbow trout. Challenge infections were performed using different salmonid strains and species, including East Atlantic salmon Salmo salar (from the Danish River Skjernå), Baltic salmon S. salar (from the Swedish River Ume Alv) and rainbow trout Oncorhynchus mykiss (from the Danish rainbow trout farm Fousing). These were compared to infection studies on the Norwegian Laerdalselva parasite form kept under exactly the same conditions in the laboratory. The Danish G. salaris form had low virulence towards both Atlantic and Baltic salmon, whereas rainbow trout proved susceptible to the parasite. The Danish G. salaris form was able to maintain a very low infection on East Atlantic salmon, but not on the Baltic salmon, which eliminated the infection within 2 wk. Rainbow trout developed infection intensities ranging up to several hundred parasites per host. The host colonization patterns of the parasite differed clearly from those of previous studies on microhabitats of the Norwegian form of G. salaris. A comparative study on morphological characters (opisthaptoral hard parts) from the Danish parasite form and Norwegian G. salaris showed no significant differences. Selected genes comprising internal transcribed spacers 1 and 2 (ITS), ribosomal RNA intergenic spacer (IGS) and cytochrome c oxidase subunit I (COI) regions were cloned and sequenced. Five sequenced ITS clones from 5 individuals of the Danish strain consistently revealed a single base substitution compared to ITS sequences from all other known species and strains of Gyrodactylus. Mitochondrial COI gene sequences demonstrated that the Danish G. salaris form is closely similar to the Laerdalselva parasite form found in Norway. The IGS sequences were highly variable, but very similar to those obtained from German isolates of G. salaris.
鲑三代虫是在丹麦一个淡水鳟鱼养殖场的虹鳟鱼中分离出来的，并且在虹鳟鱼上建立了这种特定寄生虫形态的实验室种群。使用不同的鲑科菌株和物种进行了感染挑战实验，包括东大西洋鲑（来自丹麦的斯基耶尔纳河）、波罗的海鲑（来自瑞典的于默奥河）和虹鳟（来自丹麦的福辛虹鳟养殖场）。将这些实验与在实验室相同条件下饲养的挪威莱达尔河寄生虫形态的感染研究进行了比较。丹麦的鲑三代虫形态对大西洋鲑和波罗的海鲑的毒力较低，而虹鳟被证明对该寄生虫易感。丹麦的鲑三代虫形态能够在东大西洋鲑上维持非常低的感染水平，但在波罗的海鲑上则不能，波罗的海鲑在2周内消除了感染。虹鳟鱼的感染强度发展到每个宿主多达数百个寄生虫。该寄生虫的宿主定殖模式与先前关于挪威鲑三代虫形态微生境的研究明显不同。对丹麦寄生虫形态和挪威鲑三代虫的形态特征（后吸器硬体部分）进行的比较研究没有发现显著差异。对包括内部转录间隔区1和2（ITS）、核糖体RNA基因间隔区（IGS）和细胞色素c氧化酶亚基I（COI）区域在内的选定基因进行了克隆和测序。来自丹麦菌株5个个体的5个测序ITS克隆与所有其他已知的三代虫物种和菌株的ITS序列相比，始终显示出一个单碱基替换。线粒体COI基因序列表明，丹麦的鲑三代虫形态与在挪威发现的莱达尔河寄生虫形态非常相似。IGS序列高度可变，但与从德国鲑三代虫分离株获得的序列非常相似。
