PDF(Pubmed)
Abstract：
Viral infections are still a major concern for the aquaculture industry. For salmonid fish, even though breeding strategies and vaccine development have reduced disease outbreaks, viral diseases remain among the main challenges having a negative impact on the welfare of fish and causing massive economic losses for the industry. The main entry port for viruses into the fish is through mucosal surfaces including that of the gastrointestinal tract. The contradictory functions of this surface, both creating a barrier towards the external environment and at the same time being responsible for the uptake of nutrients and ion/water regulation make it particularly vulnerable. The connection between dietary components and viral infections in fish has been poorly investigated and until now, a fish intestinal in vitro model to investigate virus-host interactions has been lacking. Here, we established the permissiveness of the rainbow trout intestinal cell line RTgutGC towards the important salmonid viruses-infectious pancreatic necrosis virus (IPNV), salmonid alphavirus (subtype 3, SAV3) and infectious salmon anemia virus (ISAV)-and explored the infection mechanisms of the three different viruses in these cells at different virus to cell ratios. Cytopathic effect (CPE), virus replication in the RTgutGC cells, antiviral cell responses and viral effects on the barrier permeability of polarized cells were investigated. We found that all virus species infected and replicated in RTgutGC cells, although with different replication kinetics and ability to induce CPE and host responses. The onset and progression of CPE was more rapid at high multiplicity of infection (MOI) for IPNV and SAV3 while the opposite was true of ISAV. A positive correlation between the MOI used and the induction of antiviral responses was observed for IPNV while a negative correlation was detected for SAV3. Viral infections compromised barrier integrity at early time points prior to observations of CPE microscopically. Further, the replication of IPNV and ISAV had a more pronounced effect on barrier function than SAV3. The in vitro infection model established herein can thus provide a novel tool to generate knowledge about the infection pathways and mechanisms used to surpass the intestinal epithelium in salmonid fish, and to study how a virus can potentially compromise gut epithelial barrier functions.
摘要：
病毒感染仍然是水产养殖业的主要问题。对于鲑鱼来说，尽管育种策略和疫苗开发减少了疾病爆发，病毒性疾病仍然是主要挑战之一，对鱼类的福利产生负面影响，并给该行业造成巨大的经济损失。病毒进入鱼的主要入口是通过粘膜表面，包括胃肠道的粘膜表面。这个表面的相互矛盾的功能，既对外部环境造成障碍，同时又负责营养的吸收和离子/水的调节，使其特别脆弱。饮食成分与鱼类病毒感染之间的联系一直没有得到充分的研究，直到现在，一直缺乏研究病毒与宿主相互作用的鱼肠体外模型。这里,我们建立了虹鳟鱼肠细胞系RTgutGC对重要的沙门氏菌传染性胰腺坏死病毒（IPNV）的宽容，沙门氏菌甲病毒（亚型3，SAV3）和传染性鲑鱼贫血病毒（ISAV）-并探索了三种不同病毒在这些细胞中以不同病毒与细胞比率的感染机制。细胞病变效应（CPE），病毒在RTgutGC细胞中复制，研究了抗病毒细胞反应和病毒对极化细胞屏障通透性的影响。我们发现所有的病毒物种都在RTgutGC细胞中感染和复制，尽管具有不同的复制动力学和诱导CPE和宿主反应的能力。对于IPNV和SAV3，CPE的发作和进展在高感染复数（MOI）下更快，而ISAV则相反。对于IPNV，观察到使用的MOI与抗病毒反应的诱导之间呈正相关，而SAV3则呈负相关。在显微镜观察CPE之前，病毒感染在早期时间点损害了屏障的完整性。Further,IPNV和ISAV的复制对屏障功能的影响比SAV3更明显。因此，本文建立的体外感染模型可以提供一种新的工具，以产生有关感染途径和机制的知识，用于超越鲑鱼的肠上皮。并研究病毒如何潜在地损害肠道上皮屏障功能。
