Laboratory of Aquatic Pathobiology, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C., Copenhagen, Denmark.
, Aquagen, Trondheim, Norway.
Sci Rep. 2021 Sep 8;11(1):17857. doi: 10.1038/s41598-021-97437-7.
Aeromonas salmonicida subsp. salmonicida, the causative agent of furunculosis, has extensive negative effects on wild and farmed salmonids worldwide. Vaccination induces some protection under certain conditions but disease outbreaks occur even in vaccinated fish. Therefore, alternative disease control approaches are required to ensure the sustainable expansion of rainbow trout aquaculture. Selective breeding can be applied to enhance host resistance to pathogens. The present work used genome-wide association study (GWAS) to identify quantitative trait loci (QTL) associated with A. salmonicida resistance in rainbow trout. A total 798 rainbow trout exposed to A. salmonicida by bath challenge revealed 614 susceptible and 138 resistant fish. Genotyping was conducted using the 57 K single nucleotide polymorphism (SNP) array and the GWAS was performed for survival and time to death phenotypes. We identified a QTL on chromosome 16 and located positional candidate genes in the proximity of the most significant SNPs. In addition, samples from exposed fish were examined for expression of 24 immune-relevant genes indicating a systematic immune response to the infection. The present work demonstrated that resistance to A. salmonicida is moderately heritable with oligogenic architecture. These result will be useful for the future breeding programs for improving the natural resistance of rainbow trout against furunculosis.
迟钝爱德华氏菌（Aeromonas salmonicida subsp. salmonicida）是疖病的病原体，它对世界范围内的野生和养殖鲑鱼科鱼类有广泛的负面影响。疫苗接种在某些条件下可以诱导一定程度的保护，但即使在接种疫苗的鱼类中也会发生疾病爆发。因此，需要替代疾病控制方法来确保虹鳟养殖业的可持续扩张。选择性育种可用于增强宿主对病原体的抗性。本研究使用全基因组关联研究（GWAS）来鉴定与虹鳟鱼对迟钝爱德华氏菌抗性相关的数量性状位点（QTL）。通过浸泡挑战将总共 798 条虹鳟鱼暴露于迟钝爱德华氏菌中，发现 614 条易感鱼和 138 条抗性鱼。使用 57K 单核苷酸多态性（SNP）芯片进行基因分型，并对存活和死亡时间表型进行全基因组关联分析。我们在第 16 号染色体上鉴定到一个 QTL，并在最显著的 SNP 附近定位了候选基因。此外，还对暴露于感染的鱼样本进行了 24 个免疫相关基因的表达分析，表明对感染有系统的免疫反应。本研究表明，对迟钝爱德华氏菌的抗性具有中度遗传力和寡基因结构。这些结果将有助于未来的虹鳟鱼抗疖病育种计划，以提高其对疖病的天然抗性。
