Adamek Mikolaj, Rebl Alexander, Matras Marek, Lodder Christian, Abd El Rahman Sahar, Stachnik Magdalena, Rakus Krzysztof, Bauer Julia, Falco Alberto, Jung-Schroers Verena, Piewbang Chutchai, Techangamsuwan Somporn, Surachetpong Win, Reichert Michal, Tetens Jens, Steinhagen Dieter
Fish Disease Research Unit, Institute for Parasitology, University of Veterinary Medicine Hannover, Hannover, Germany.
Fish Genetics Unit, Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany.
Fish Shellfish Immunol. 2022 May;124:118-133. doi: 10.1016/j.fsi.2022.03.027. Epub 2022 Mar 30.
The emergence of viral diseases affecting fish and causing very high mortality can lead to the disruption of aquaculture production. Recently, this occurred in Nile tilapia aquaculture where a disease caused by a systemic infection with a novel virus named tilapia lake virus (TiLV) caused havoc in cultured populations. With mortality surpassing 90% in young tilapia, the disease caused by TiLV has become a serious challenge for global tilapia aquaculture. In order to partly mitigate the losses, we explored the natural resistance to TiLV-induced disease in three genetic strains of tilapia which were kept at the University of Göttingen, Germany. We used two strains originating from Nilotic regions (Lake Mansala (MAN) and Lake Turkana (ELM)) and one from an unknown location (DRE). We were able to show that the virus is capable of overcoming the natural resistance of tilapia when injected, providing inaccurate mortality results that might complicate finding the resistant strains. Using the cohabitation infection model, we found an ELM strain that did not develop any clinical signs of the infection, which resulted in nearly 100% survival rate. The other two strains (DRE and MAN) showed severe clinical signs and much lower survival rates of 29.3% in the DRE strain and 6.7% in the MAN strain. The disease resistance of tilapia from the ELM strain was correlated with lower viral loads both at the mucosa and internal tissues. Our results suggest that the lower viral load could be caused by a higher magnitude of a mx1-based antiviral response in the initial phase of infection. The lower pro-inflammatory responses also found in the resistant strain might additionally contribute to its protection from developing pathological changes related to the disease. In conclusion, our results suggest the possibility of using TiLV-resistant strains as an ad hoc, cost-effective solution to the TiLV challenge. However, as the fish from the disease-resistant strain still retained significant virus loads in liver and brain and thus could become persistent virus carriers, they should be used within an integrative approach also combining biosecurity, diagnostics and vaccination measures..
影响鱼类并导致极高死亡率的病毒性疾病的出现会导致水产养殖生产中断。最近，尼罗罗非鱼养殖中就出现了这种情况，一种由名为罗非鱼湖病毒（TiLV）的新型病毒引起的系统性感染疾病在养殖群体中造成了严重破坏。在幼龄罗非鱼中死亡率超过90%，由TiLV引起的疾病已成为全球罗非鱼养殖的严峻挑战。为了部分减轻损失，我们在德国哥廷根大学饲养的三个罗非鱼遗传品系中探索了对TiLV诱导疾病的天然抵抗力。我们使用了两个源自尼罗河流域地区的品系（曼萨拉湖（MAN）和图尔卡纳湖（ELM））以及一个来源不明的品系（DRE）。我们能够证明，当注射病毒时，该病毒能够克服罗非鱼的天然抵抗力，提供不准确的死亡率结果，这可能会使寻找抗性品系变得复杂。使用同居感染模型，我们发现一个ELM品系没有出现任何感染的临床症状，其存活率接近100%。另外两个品系（DRE和MAN）表现出严重的临床症状，存活率低得多，DRE品系为29.3%，MAN品系为6.7%。来自ELM品系的罗非鱼的抗病性与黏膜和内部组织中较低的病毒载量相关。我们的结果表明，较低的病毒载量可能是由感染初始阶段基于mx1的抗病毒反应的较高强度引起的。在抗性品系中还发现的较低促炎反应可能额外有助于其免受与疾病相关的病理变化的影响。总之，我们的结果表明使用抗TiLV品系作为应对TiLV挑战的临时、经济有效的解决方案是有可能的。然而，由于来自抗病品系的鱼在肝脏和大脑中仍保留大量病毒载量，因此可能成为持续的病毒携带者，它们应在综合方法中使用，该方法还应结合生物安全、诊断和疫苗接种措施。
