Gharamah Abdullah A, Legaspi Renald J, Richardson Elisabeth H, Fetherman Eric R, Magor Katharine E, Hanington Patrick C
School of Public Health, University of Alberta, 357 South Academic Building, Edmonton, Alberta, Canada T6G 2G7.
Department of Biological Sciences, University of Alberta, CW 405, Biological Sciences Building, Edmonton, Alberta, Canada T6G 2E9.
Int J Parasitol. 2025 Sep 4. doi: 10.1016/j.ijpara.2025.08.016.
Whirling disease is a debilitating disease of Rainbow Trout caused by Myxobolus cerebralis. The parasite invasion leads to skeletal deformities, neurological impairment, and high mortality. Since its introduction to North America, M. cerebralis has severely impacted wild trout populations in several regions. In this study, we focus on a promising Whirling disease-resistant Rainbow Trout strain developed in the Gunnison River, Colorado. We analyzed the genomes and transcriptomes of this resistant strain at different time points after challenge with M. cerebralis. Signature selection analysis revealed several regions across the genome under selection, with the highest density found on chromosome 23. Several genes found in areas under selection are associated with neuron differentiation and nervous system development. Also, several immuno-genes were under selection, including several with relevance to the innate and adaptive immune response. The transcriptomic analysis revealed that the Gunnison River Rainbow Trout develops a comprehensive immune response after exposure to M. cerebralis. This is supported by the significant enrichment of specific immune response pathways, including differentiation and activation of B-cells and T-cells. These results suggest that certain immune pathways are likely to participate in building the Gunnison River Rainbow Trout's early, mid, and long-term immune response against M. cerebralis, while other pathways related to nervous system development may help juvenile fish survive the effects of Whirling disease. The transcriptomic analysis also reveals that more than half of the top 20 upregulated immune genes are components of the complement pathway. Notably, CD209 (DC-SIGN), a critical gene involved in antigen recognition and dendritic cell function, is among the most highly upregulated genes. The results also indicate the presence of a specific region on chromosome 9 in this strain, previously linked to resistance to this disease. This may explain this strain's strong disease resistance and survival capacity in natural environments.
旋转病是由脑粘体虫引起的虹鳟鱼的一种衰弱性疾病。寄生虫入侵会导致骨骼畸形、神经损伤和高死亡率。自从脑粘体虫被引入北美以来，它已经严重影响了几个地区的野生鳟鱼种群。在这项研究中，我们聚焦于在科罗拉多州甘尼森河培育出的一种有前景的抗旋转病虹鳟鱼品系。我们分析了该抗性品系在受到脑粘体虫攻击后不同时间点的基因组和转录组。特征选择分析揭示了基因组中多个处于选择状态的区域，其中在23号染色体上的密度最高。在选择区域中发现的几个基因与神经元分化和神经系统发育有关。此外，几个免疫基因也处于选择状态，包括一些与先天免疫和适应性免疫反应相关的基因。转录组分析表明，甘尼森河虹鳟鱼在接触脑粘体虫后会产生全面的免疫反应。这得到了特定免疫反应途径显著富集的支持，包括B细胞和T细胞的分化和激活。这些结果表明，某些免疫途径可能参与构建甘尼森河虹鳟鱼针对脑粘体虫的早期、中期和长期免疫反应，而其他与神经系统发育相关的途径可能有助于幼鱼在旋转病的影响下存活。转录组分析还显示，上调幅度最大的20个免疫基因中，超过一半是补体途径的组成部分。值得注意的是，参与抗原识别和树突状细胞功能的关键基因CD209（DC-SIGN）是上调幅度最高的基因之一。结果还表明，该品系的9号染色体上存在一个特定区域，此前已与对这种疾病的抗性相关联。这可能解释了该品系在自然环境中的强抗病性和生存能力。
