Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China.
Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
Front Immunol. 2019 Dec 18;10:2878. doi: 10.3389/fimmu.2019.02878. eCollection 2019.
The digestive tract is a unique series of organs that is inhabited by a range of commensal microbes while also exposed to an overwhelming load of dietary antigens. It is widely known that mammals have evolved complex and efficient immune strategies to protect the mucosa of the digestive tract. However, in the early vertebrates, the roles of mucosal immune defense and microbial communities in the different segments of the digestive tract are not well-understood. Here, we constructed a bath infection model with infectious hematopoietic necrosis virus (IHNV) in rainbow trout (). Importantly, following viral infection, we found that the IHNV distribution and the reactions of immune-related genes had similar trends that decreased across the digestive tract. Hematoxylin and eosin (H & E) and alcian blue (A & B) staining of the trout digestive tract showed that the pathological changes only occurred in the buccal and pharyngeal mucosal tissues. Moreover, the increased diversity of the microbial community was only detected in the buccal mucosa through 16S rRNA gene sequencing, suggesting that the magnitude of the immune response and microbial community changes are related to the IHNV load and the original microbial diversity. In addition, the loss of digestive tract dominant species and increased colonization of opportunistic bacteria were discovered in the buccal mucosal surface indicating that a secondary bacterial infection occurred in this mucosal tissue.
消化道是一系列独特的器官，其中栖息着一系列共生微生物，同时也暴露于大量饮食抗原之下。众所周知，哺乳动物进化出了复杂而有效的免疫策略来保护消化道的黏膜。然而，在早期的脊椎动物中，黏膜免疫防御和微生物群落在消化道不同部位的作用还没有被很好地理解。在这里，我们构建了虹鳟鱼（）感染传染性造血坏死病毒（IHNV）的浴感染模型。重要的是，在病毒感染后，我们发现 IHNV 的分布和免疫相关基因的反应呈相似的趋势，即沿着消化道逐渐减少。对虹鳟鱼消化道的苏木精和伊红（H & E）和阿尔辛蓝（A & B）染色显示，病理变化仅发生在口腔和咽黏膜组织中。此外，通过 16S rRNA 基因测序仅在口腔黏膜中检测到微生物群落多样性增加，这表明免疫反应和微生物群落变化的幅度与 IHNV 负荷和原始微生物多样性有关。此外，在口腔黏膜表面发现了消化道优势种的丧失和机会性细菌的定植增加，表明该黏膜组织发生了二次细菌感染。
