Epidermal mucus is an important barrier and regulating mediator in fish. MicroRNAs (miRNAs) are proved to be involved in various biological processes, also as promising biomarkers for disease diagnosis. Vibrio harveyi has long been a noticeable bacterial pathogen in Cynoglossus semilaevis aquaculture. To find the evidence whether there are indicating miRNAs in mucus and whether the miRNAs are related to infections caused by V. harveyi, miRNA profiles of mucus from V. harveyi infected fish and healthy controls were screened by small RNA sequencing and verified by quantitative real-time PCR. This is the first report about miRNA profiling of flatfish mucus, aiming at illustrating the pathogenesis of V. harveyi caused infection and developing disease-related biomarkers. The results revealed significant differences in expression levels of some miRNAs between infected fish and healthy ones. Three hundred differentially expressed miRNAs were obtained after filtering through FC > 2 or FC < 0.5 and most of the differential miRNAs were downregulated. After verification through qRT-PCR, four unique miRNAs, dre-miR-451, dre-miR-184, dre-miR-205-5p > ssa-miR-205b-5p, and dre-miR-181a-5p > ssa-miR-181a-5p, were identified as V. harveyi infection-related signatures, consistent with sequencing trend. The expression levels of these four miRNAs in the infected fish were all significantly lower than controls. These miRNAs in mucus could be used to differentiate diseased and healthy fish in a non-invasive way with practical value for large-scale disease screening. They also provided new insights into the mechanism underlying the bacterial infections in fish.

表皮粘液是鱼类重要的屏障和调节介质。MicroRNAs (miRNAs) 被证明参与各种生物过程，也是疾病诊断的有希望的生物标志物。长期以来，哈维弧菌一直是半滑舌鲆水产养殖中一种引人注目的细菌病原体。为了寻找粘液中是否存在指示性 miRNA 以及这些 miRNA 是否与哈维伊弧菌引起的感染相关的证据，通过小 RNA 测序筛选了哈维伊弧菌感染的鱼和健康对照的粘液的 miRNA 谱，并通过定量实时验证。时间 PCR。这是关于比目鱼粘液的 miRNA 分析的第一份报告，旨在阐明哈维弧菌的发病机制导致感染和发展与疾病相关的生物标志物。结果表明，受感染的鱼和健康的鱼之间某些 miRNA 的表达水平存在显着差异。通过FC>2或FC<0.5过滤后获得了300个差异表达的miRNA，大多数差异miRNA被下调。通过 qRT-PCR 验证后，四个独特的 miRNA，dre-miR-451、dre-miR-184、dre-miR-205-5p > ssa-miR-205b-5p 和 dre-miR-181a-5p > ssa- miR-181a-5p，被鉴定为V. harveyi感染相关特征，与测序趋势一致。这四种miRNA在受感染鱼中的表达水平均显着低于对照。粘液中的这些 miRNA 可用于以非侵入性方式区分患病鱼和健康鱼，对大规模疾病筛查具有实用价值。他们还为鱼类细菌感染的潜在机制提供了新的见解。