Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, P.O. Box 369, NO-0102 Oslo, Norway.
Department of Veterinary Microbiology, Parasitology and Biotechnology, College of Veterinary Medicine and Biomedical Sciences, Sokoine University of Agriculture, P. O. Box 3019 Chuo Kikuu, Morogoro, Tanzania.
Viruses. 2019 Dec 12;11(12):1152. doi: 10.3390/v11121152.
Tilapia lake virus (TiLV) is a negative-sense single-stranded RNA (-ssRNA) icosahedral virus classified to be the only member in the family Amnoonviridae. Although TiLV segment-1 shares homology with the influenza C virus PB1 and has four conserved motifs similar to influenza A, B, and C polymerases, it is unknown whether there are other properties shared between TiLV and orthomyxovirus. In the present study, we wanted to determine whether TiLV agglutinated avian and piscine erythrocytes, and whether its replication was inhibited by lysosomotropic agents, such as ammonium chloride (NHCl), as seen for orthomyxoviruses. Our findings showed that influenza virus strain A/Puerto Rico/8 (PR8) was able to hemagglutinate turkey (), Atlantic salmon ( L), and Nile tilapia () red blood cells (RBCs), while infectious salmon anemia virus (ISAV) only agglutinated Atlantic salmon, but not turkey or tilapia, RBCs. In contrast to PR8 and ISAV, TiLV did not agglutinate turkey, Atlantic salmon, or tilapia RBCs. qRT-PCR analysis showed that 30 mM NHCl, a basic lysosomotropic agent, neither inhibited nor enhanced TiLV replication in E-11 cells. There was no difference in viral quantities in the infected cells with or without NHCl treatment during virus adsorption or at 1, 2, and 3 h post-infection. Given that hemagglutinin proteins that bind RBCs also serve as ligands that bind host cells during virus entry leading to endocytosis in orthomyxoviruses, the data presented here suggest that TiLV may use mechanisms that are different from orthomyxoviruses for entry and replication in host cells. Therefore, future studies should seek to elucidate the mechanisms used by TiLV for entry into host cells and to determine its mode of replication in infected cells.
罗非鱼湖病毒（TiLV）是一种负义单链 RNA（-ssRNA）二十面体病毒，被归类为仅有的 Amnoonviridae 科成员。尽管 TiLV 片段-1 与流感 C 病毒 PB1 具有同源性，并具有四个类似于流感 A、B 和 C 聚合酶的保守基序，但尚不清楚 TiLV 是否与正粘病毒具有其他共同特性。在本研究中，我们想确定 TiLV 是否能够凝集禽类和鱼类的红细胞，以及其复制是否像正粘病毒一样被溶酶体趋化性药物（如氯化铵（NHCl））抑制。我们的研究结果表明，流感病毒株 A/Puerto Rico/8（PR8）能够凝集火鸡（）、大西洋三文鱼（ L）和尼罗罗非鱼（）的红细胞（RBC），而传染性鲑鱼贫血病毒（ISAV）仅凝集大西洋三文鱼，而不凝集火鸡或罗非鱼的 RBC。与 PR8 和 ISAV 相反，TiLV 不能凝集火鸡、大西洋三文鱼或罗非鱼的 RBC。qRT-PCR 分析表明，30 mM NHCl 作为一种碱性溶酶体趋化性药物，既不能抑制也不能增强 E-11 细胞中 TiLV 的复制。在病毒吸附或感染后 1、2 和 3 小时，无论是否用 NHCl 处理，感染细胞中的病毒数量都没有差异。鉴于结合 RBC 的血凝素蛋白也作为在正粘病毒中进入宿主细胞时结合宿主细胞的配体，导致内吞作用，这里呈现的数据表明，TiLV 可能使用与正粘病毒不同的机制进入和复制宿主细胞。因此，未来的研究应该旨在阐明 TiLV 进入宿主细胞的机制，并确定其在感染细胞中的复制方式。
