Gill health is one of the main concerns for Atlantic salmon aquaculture, and Amoebic Gill Disease (AGD), attributable to infection by the amoeba Neoparamoeba perurans, is a frequent cause of morbidity. In the absence of preventive measures, increasing genetic resistance of salmon to AGD via selective breeding can reduce the incidence of the disease and mitigate gill damage. Understanding the mechanisms leading to AGD resistance and the underlying causative genomic features can aid in this effort, while also providing critical information for the development of other control strategies. AGD resistance is considered to be moderately heritable, and several putative QTL have been identified. The aim of the current study was to improve understanding of the mechanisms underlying AGD resistance, and to identify putative causative genomic factors underlying the QTL. To achieve this, RNA was extracted from the gill and head kidney of AGD resistant and susceptible animals following a challenge with N. perurans, and sequenced. Comparison between resistant and susceptible animals primarily highlighted differences mainly in the local immune response in the gill, involving red blood cell genes and genes related to immune function and cell adhesion. Differentially expressed immune genes pointed to a contrast in Th2 and Th17 responses, which is consistent with the increased heritability observed after successive challenges with the amoeba. Five QTL-region candidate genes showed differential expression, including a gene connected to interferon responses (GVINP1), a gene involved in systemic inflammation (MAP4K4), and a positive regulator of apoptosis (TRIM39). Analyses of allele-specific expression highlighted a gene in the QTL region on chromosome 17, cellular repressor of E1A-stimulated genes 1 (CREG1), showing allelic differential expression suggestive of a cis-acting regulatory variant. In summary, this study provides new insights into the mechanisms of resistance to AGD in Atlantic salmon, and highlights candidate genes for further functional studies that can further elucidate the genomic mechanisms leading to resistance and contribute to enhancing salmon health via improved genomic selection.

中文翻译：

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使用RNA测序表征大西洋鲑对阿米巴g病的遗传抗性的潜在机制

Atlantic鱼的健康是大西洋鲑鱼养殖的主要问题之一，而阿米巴新para虫的感染引起的阿米巴bic病（AGD）是发病的常见原因。在没有预防措施的情况下，通过选择性育种提高鲑鱼对AGD的遗传抗性可以减少疾病的发生并减轻g的损害。了解导致AGD抗性的机制和潜在的致病基因组特征可以帮助完成这项工作，同时还为开发其他控制策略提供关键信息。AGD抗性被认为是中等遗传性的，并且已经鉴定出几个推定的QTL。本研究的目的是增进对AGD耐药性潜在机制的了解，并确定QTL潜在的致病基因组因素。为了达到这个目的，在对付百日咳猪笼草的挑战后，从抗AGD的易感动物的腮和头肾中提取RNA，并进行测序。抗药性动物和易感动物之间的比较主要着眼于mainly的局部免疫反应，主要涉及红细胞基因以及与免疫功能和细胞粘附相关的基因。差异表达的免疫基因指出Th2和Th17反应的差异，这与变形虫连续攻击后观察到的遗传力增加是一致的。5个QTL区域候选基因表现出差异表达，包括与干扰素应答相关的基因（GVINP1），与全身性炎症有关的基因（MAP4K4），和凋亡的正调节剂（TRIM39）。等位基因特异性表达的分析突出显示了17号染色​​体QTL区域中的一个基因，E1A刺激的基因1（CREG1）的细胞阻遏物，表明等位基因差异表达提示顺式作用的调控变异。总而言之，这项研究为大西洋鲑对AGD的抗性机制提供了新见解，并突出了用于进一步功能研究的候选基因，这些候选基因可以进一步阐明导致抗性的基因组机制，并通过改善基因组选择来促进鲑鱼健康。