Atlantic cod has lost the Major Histocompatibility complex class II pathway – central to pathogen presentation, humoral response and immunity. Here, we investigate the immunological response of Atlantic cod subsequent to dip vaccination with Vibrio anguillarum bacterin using transcriptome sequencing. The experiment was conducted on siblings from an Atlantic cod family found to be highly susceptible towards vibriosis where vaccination has demonstrated improved pathogen resistance. Gene expression analyses at 2, 4, 21 and 42 days post vaccination revealed GO-term enrichment for muscle, neuron and metabolism-related pathways. In-depth characterization of immune-related GO terms demonstrated down-regulation of MHCI antigen presentation, C-type lectin receptor signaling and granulocyte activation over time. Phagocytosis, interferon-gamma signaling and negative regulation of innate immunity were increasingly up-regulated over time. Individual differentially expressed immune genes implies weak initiation of acute phase proteins with little or no inflammation. Furthermore, gene expression indicates presence of T-cells, NK-like cells, B-cells and monocytes/macrophages. Three MHCI transcripts were up-regulated with B2M and SEC61. Overall, we find no clear immune-related transcriptomic response which could be attributed to Atlantic cod's alternative immune system. However, we cannot rule out that this response is related to vaccination protocol/sampling strategy. Earlier functional studies demonstrate significant memory in Atlantic cod post dip vaccination and combined with our results indicate the presence of other adaptive immunity mechanisms. In particular, we suggest that further investigations should look into CD8+ memory T-cells, γδ T-cells, T-cell independent memory or memory induced through NK-like/other lymphoid cells locally in the mucosal lining for this particular vaccination strategy.

大西洋鳕鱼已经失去了主要的组织相容性复杂的II类途径-对病原体呈递，体液反应和免疫至关重要。在这里，我们调查大西洋的免疫反应鳕之后浸接种弧菌 鳗使用转录组测序的细菌。该实验是在一个大西洋鳕鱼家族的兄弟姐妹中进行的，发现该兄弟姐妹非常容易发生弧菌病，其中疫苗接种已显示出改善的病原体抵抗力。疫苗接种后第2、4、21和42天的基因表达分析显示，GO-term富集了肌肉，神经元和代谢相关途径。免疫相关的GO术语的深入表征证明了MHCI抗原呈递，C型凝集素受体信号转导和粒细胞活化随时间的下调。随着时间的流逝，吞噬作用，干扰素-γ信号传导和先天免疫的负调节作用越来越多。个体差异表达的免疫基因意味着急性期蛋白的弱启动，几乎没有或没有炎症。此外，基因表达表明存在T细胞，NK样细胞，B细胞和单核细胞/巨噬细胞。三MHCI转录本被B2M和SEC61上调。总的来说，我们没有发现明显的与免疫相关的转录组反应，这可以归因于大西洋鳕鱼的替代免疫系统。但是，我们不能排除这种反应与疫苗接种方案/抽样策略有关。较早的功能研究表明，浸入疫苗后大西洋鳕鱼具有显着的记忆力，结合我们的结果表明存在其他适应性免疫机制。特别是，我们建议针对这种特定的疫苗接种策略，应进一步研究CD8 +记忆性T细胞，γδT细胞，独立于T细胞的记忆或通过粘膜内层局部NK样/其他淋巴样细胞诱导的记忆。