Department of Veterinary Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand.
Department of Physiology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand.
J Fish Dis. 2023 Jun;46(6):643-651. doi: 10.1111/jfd.13775. Epub 2023 Feb 27.
Tilapia lake virus disease (TiLVD) is an emerging disease in tilapia that is associated with mass mortality affecting global tilapia aquaculture. In this study, red hybrid tilapias (Oreochromis spp.) were experimentally infected by intracoelomic injection with Tilapia lake virus (TiLV) to gain a better understanding of the clinicopathological changes during infection. Pale bodies and gill were observed in infected fish after 7 days of post-challenge (dpc) associated with severe anaemia. Further haematological analysis in TiLV-infected fish revealed decreased levels of haemoglobin and haematocrit at 3 dpc. Common pathological findings included pale and friable liver, pale intestine with catarrhal content, and dark and shrunken spleen in TiLV-infected fish at 7 dpc and 14 dpc. Histologically, reduced numbers of red blood cells and accumulation of melano-macrophage centre in the spleen were found in infected fish at 3 dpc, and severe lesions were more commonly observed at 7 and 14 dpc. Lymphocyte infiltration, syncytial cell formation and multifocal necrotic hepatitis were the prominent pathological findings in the liver of infected fish. The severity of pathological changes was associated with TiLV-infection with higher viral loads and with the expression pattern of pro-inflammatory cytokines and antiviral genes, including interferon regulatory factor 1 (irf1), interleukin (il-8), radical s-adenosyl methionine domain containing 2 (rsad2) and mx. Our study provides a comprehensive analysis of the haematological profile and pathological changes in tilapia during TiLV infection. Overall, lesions present in various organs, together with alteration of host immune response in TiLV-infected fish, indicate the systemic infection of this virus. The knowledge gained from this study improves our understanding of how TiLV causes pathological and haematological changes in tilapia.
罗非鱼湖病毒病（TiLVD）是一种新兴的罗非鱼疾病，与全球罗非鱼养殖业的大规模死亡有关。在本研究中，通过体腔注射法用罗非鱼湖病毒（TiLV）感染杂交红罗非鱼（Oreochromis spp.），以更好地了解感染过程中的临床病理变化。感染鱼在攻毒后 7 天（dpc）出现苍白体和鳃，伴有严重贫血。TiLV 感染鱼的进一步血液学分析显示，在 3 dpc 时血红蛋白和血细胞比容水平下降。TiLV 感染鱼在 7 dpc 和 14 dpc 时常见的病理变化包括肝脏苍白易碎、肠道苍白有卡他性内容物、脾脏暗黑皱缩。组织学上，在 3 dpc 时发现感染鱼的红细胞数量减少和脾脏中的黑色素巨噬细胞中心堆积，在 7 和 14 dpc 时观察到更严重的病变。淋巴细胞浸润、合胞细胞形成和多灶性坏死性肝炎是感染鱼肝脏的突出病理变化。病理变化的严重程度与 TiLV 感染相关，与病毒载量较高以及促炎细胞因子和抗病毒基因（包括干扰素调节因子 1（irf1）、白细胞介素（il-8）、激进 s-腺苷甲硫氨酸结构域包含 2（rsad2）和 mx）的表达模式相关。本研究全面分析了 TiLV 感染期间罗非鱼的血液学特征和病理变化。总之，各种器官的病变以及 TiLV 感染鱼宿主免疫反应的改变表明该病毒的全身感染。从这项研究中获得的知识提高了我们对 TiLV 如何引起罗非鱼病理和血液学变化的理解。
