Marine Scotland Science, Victoria Road, P,O, Box 101, Aberdeen AB11 9DB, UK.
BMC Microbiol. 2013 Dec 6;13:285. doi: 10.1186/1471-2180-13-285.
Bacterial kidney disease (BKD), caused by Renibacterium salmoninarum, is a bacterial disease of fish, which is both geographically widespread and difficult to control. Previously, application of various molecular typing methods has failed to reliably discriminate between R. salmoninarum isolates originating from different host species and geographic areas. The current study aimed to utilize multilocus variable number tandem repeats (VNTR) to investigate inter-strain variation of R. salmoninarum to establish whether host-specific populations exist in Atlantic salmon and rainbow trout respectively. Such information would be valuable in risk assessment of transmission of R. salmoninarum in a multispecies aquaculture environment.
The present analysis utilizing sixteen VNTRs distinguished 17 different haplotypes amongst 41 R. salmoninarum isolates originating from Atlantic salmon and rainbow trout in Scotland, Norway and the US. The VNTR typing system revealed two well supported groups of R. salmoninarum haplotypes. The first group included R. salmoninarum isolates originating from both Atlantic salmon and rainbow trout circulating in Scottish and Norwegian aquaculture, in addition to the type strain ATCC33209T originating from Chinook salmon in North America. The second group comprised isolates found exclusively in Atlantic salmon, of mainly wild origin, including isolates NCIB1114 and NCIB1116 associated with the original Dee disease in Scotland.
The present study confirmed that VNTR analysis can be successfully applied to discriminate R. salmoninarum strains. There was no clear distinction between isolates originating from Atlantic salmon and rainbow trout as several haplotypes in group 1 clustered together R. salmoninarum isolates from both species. These findings indicate a potential exchange of pathogens between Atlantic salmon and rainbow trout in Scottish and Norwegian aquaculture during the last 20 years. In a scenario of expansion of rainbow trout farming into the marine environment, appropriate biosecurity measures to minimize disease occurrence are advised. The present results also suggest that R. salmoninarum isolates circulating in European aquaculture over the last 20 years are genetically distant to the wild strains originally causing BKD in the rivers Dee and Spey.
由鲑鱼弧菌（Renibacterium salmoninarum）引起的细菌性肾病（BKD）是一种鱼类细菌性疾病，它在地理上广泛分布且难以控制。以前，应用各种分子分型方法未能可靠地区分源自不同宿主物种和地理区域的鲑鱼弧菌分离株。本研究旨在利用多位点可变数串联重复（VNTR）来研究鲑鱼弧菌菌株间的变异性，以确定鲑鱼弧菌是否分别存在于大西洋鲑鱼和虹鳟鱼的宿主特异性群体中。此类信息对于评估多物种水产养殖环境中鲑鱼弧菌传播的风险非常有价值。
本研究利用 16 个 VNTR 区分了来自苏格兰、挪威和美国的大西洋鲑鱼和虹鳟鱼的 41 株鲑鱼弧菌分离株中的 17 种不同单倍型。VNTR 分型系统显示鲑鱼弧菌的单倍型存在两个支持良好的群组。第一组包括源自苏格兰和挪威水产养殖中的大西洋鲑鱼和虹鳟鱼循环的鲑鱼弧菌分离株，以及源自北美的奇努克鲑鱼的 ATCC33209T 型株。第二组由仅在大西洋鲑鱼中发现的分离株组成，主要来自野生种群，包括与苏格兰 Dee 病有关的 NCIB1114 和 NCIB1116 分离株。
本研究证实 VNTR 分析可成功用于区分鲑鱼弧菌菌株。源自大西洋鲑鱼和虹鳟鱼的分离株之间没有明显区别，因为第 1 组中的几个单倍型聚集了来自这两个物种的鲑鱼弧菌分离株。这些发现表明，在过去 20 年中，苏格兰和挪威水产养殖中的大西洋鲑鱼和虹鳟鱼之间可能存在病原体的交换。在虹鳟鱼养殖向海洋环境扩张的情况下，建议采取适当的生物安全措施来最大限度地减少疾病的发生。本研究结果还表明，过去 20 年在欧洲水产养殖中循环的鲑鱼弧菌分离株与最初在 Dee 河和 Spey 河引起 BKD 的野生菌株在遗传上相距甚远。
