Brosnahan Cara L, Munday John S, Ha Hye Jeong, Preece Mark, Jones John B
Animal Health Laboratory, Ministry for Primary Industries, Upper Hutt, New Zealand.
School of Veterinary Science, Massey University, Palmerston North, New Zealand.
J Fish Dis. 2019 Jan;42(1):85-95. doi: 10.1111/jfd.12909. Epub 2018 Nov 8.
A total of 777 fish from three growing regions of New Zealand Chinook salmon farms comprising of five sites were tested. Quantitative PCR was used to determine the distribution of New Zealand rickettsia-like organism and Tenacibaculum maritimum. Genetic information from these bacteria were then compared with strains reported worldwide. Using this information, suggested associations of pathogens with clinically affected fish were made. NZ-RLO was detected in two of the three regions, and T. maritimum was detected in all regions. Three strains of NZ-RLO were identified during this study. Based on analysis of the ITS rRNA gene, NZ-RLO1 appears to be part of an Australasian grouping sharing high similarity with the Tasmanian RLO, NZ-RLO2 was shown to be the same as an Irish strain, and NZ-RLO3 was shown be closely related to two strains from Chile. Based on multi-locus sequence typing, the New Zealand T. maritimum was the same as Australian strains. NZ-RLOs were detected more frequently in fish with skin ulcers than fish without skin ulcers. While additional research is required to investigate the pathogenicity of these organisms, this is the first time that NZ-RLOs have been associated with the development of clinical infections in farmed Chinook salmon.
对来自新西兰奇努克鲑鱼养殖场三个养殖区域（共五个地点）的777条鱼进行了检测。采用定量PCR法测定新西兰立克次氏体样生物和海生黄杆菌的分布情况。然后将这些细菌的遗传信息与全球报道的菌株进行比较。利用这些信息，提出了病原体与临床感染鱼之间的关联。在三个区域中的两个区域检测到了新西兰立克次氏体样生物（NZ-RLO），所有区域均检测到了海生黄杆菌。在本研究中鉴定出了三株NZ-RLO。基于内部转录间隔区（ITS）rRNA基因分析，NZ-RLO1似乎是与塔斯马尼亚立克次氏体样生物具有高度相似性的澳大拉西亚菌群的一部分，NZ-RLO2与一株爱尔兰菌株相同，NZ-RLO3与来自智利的两株菌株密切相关。基于多位点序列分型，新西兰海生黄杆菌与澳大利亚菌株相同。在有皮肤溃疡的鱼中比在没有皮肤溃疡的鱼中更频繁地检测到NZ-RLO。虽然需要进一步研究来调查这些生物的致病性，但这是首次将NZ-RLO与养殖奇努克鲑鱼临床感染的发生联系起来。
