Glycerophospholipid remodeling is critical for orthoflavivirus infection

Flavivirus infection is tightly connected to host lipid metabolism. Here, we performed shotgun lipidomics of cells infected with neurotropic Zika, West Nile, and tick-borne encephalitis viruses, as well as dengue and yellow fever virus. Early in infection specific lipids accumulated, e.g., neutral lipids in Zika and some lyso-phospholipids in all infections. Ceramide levels increased following infection with viruses that cause a cytopathic effect. In addition, fatty acid desaturation as well as glycerophospholipid metabolism were significantly altered. Importantly, depletion of enzymes involved in phosphatidylserine metabolism as well as phosphatidylinositol biosynthesis reduced orthoflavivirus titers and cytopathic effects while inhibition of fatty acid monounsaturation only rescued from virus-induced cell death. Interestingly, interfering with ceramide synthesis had opposing effects on virus replication and cytotoxicity depending on the targeted enzyme. Thus, lipid remodeling by orthoflaviviruses includes distinct changes but also common patterns shared by several viruses that are needed for efficient infection and replication. Overall design: Shotgun lipidomics and transcriptomics of cells infected with neurotropic Zika, West Nile, and tick-borne encephalitis viruses, as well as dengue and yellow fever virus. Early in infection specific lipids accumulated, e.g., neutral lipids in Zika and some lyso-phospholipids in all infections.

黄病毒（Flavivirus）感染与宿主脂质代谢紧密关联。本研究针对感染嗜神经性寨卡病毒、西尼罗河病毒、蜱传脑炎病毒，以及登革病毒和黄热病毒的细胞开展鸟枪法脂质组学（shotgun lipidomics）分析。感染早期可观测到特异性脂质蓄积现象：例如寨卡病毒感染组中的中性脂质，以及所有感染组均出现的部分溶血磷脂（lyso-phospholipids）。
感染可引发细胞病变效应的病毒后，神经酰胺（ceramide）水平会出现升高。此外，脂肪酸去饱和作用以及甘油磷脂代谢均发生显著改变。值得注意的是，敲除参与磷脂酰丝氨酸（phosphatidylserine）代谢以及磷脂酰肌醇（phosphatidylinositol）生物合成的酶类，可降低正黄病毒（orthoflavivirus）滴度并减轻细胞病变效应；而抑制脂肪酸单不饱和化仅能缓解病毒诱导的细胞死亡。有趣的是，靶向不同酶类干预神经酰胺合成时，对病毒复制与细胞毒性的影响呈现截然相反的效果。由此可见，正黄病毒介导的脂质重塑既存在病毒特异性的改变模式，也包含多种病毒共有的、有助于高效感染与复制的共性特征。
实验总体设计：对感染嗜神经性寨卡病毒、西尼罗河病毒、蜱传脑炎病毒，以及登革病毒和黄热病毒的细胞开展鸟枪法脂质组学与转录组学（transcriptomics）分析，以观测感染早期出现的特异性脂质蓄积现象——例如寨卡病毒感染组中的中性脂质，以及所有感染组均存在的部分溶血磷脂。