Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.
Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
J Virol. 2021 Feb 24;95(6). doi: 10.1128/JVI.02323-20.
Cholesterol has been implicated in various viral life cycle steps for different enveloped viruses, including viral entry into host cells, cell-cell fusion, and viral budding from infected cells. Enveloped viruses acquire their membranes from their host cells. Although cholesterol has been associated with the binding and entry of various enveloped viruses into cells, cholesterol's exact function in the viral-cell membrane fusion process remains largely elusive, particularly for the paramyxoviruses. Furthermore, paramyxoviral fusion occurs at the host cell membrane and is essential for both virus entry (virus-cell fusion) and syncytium formation (cell-cell fusion), central to viral pathogenicity. Nipah virus (NiV) is a deadly member of the family, which also includes Hendra, measles, mumps, human parainfluenza, and various veterinary viruses. The zoonotic NiV causes severe encephalitis, vasculopathy, and respiratory symptoms, leading to a high mortality rate in humans. We used NiV as a model to study the role of membrane cholesterol in paramyxoviral membrane fusion. We used a combination of methyl-beta cyclodextrin (MβCD), lovastatin, and cholesterol to deplete or enrich cell membrane cholesterol outside cytotoxic concentrations. We found that the levels of cellular membrane cholesterol directly correlated with the levels of cell-cell fusion induced. These phenotypes were paralleled using NiV/vesicular stomatitis virus (VSV)-pseudotyped viral infection assays. Remarkably, our mechanistic studies revealed that cholesterol reduces an early F-triggering step but enhances a late fusion pore formation step in the NiV membrane fusion cascade. Thus, our results expand our mechanistic understanding of the paramyxoviral/henipaviral entry and cell-cell fusion processes. Cholesterol has been implicated in various steps of the viral life cycle for different enveloped viruses. Nipah virus (NiV) is a highly pathogenic enveloped virus in the genus within the family, capable of causing a high mortality rate in humans and high morbidity in domestic and agriculturally important animals. The role of cholesterol for NiV or the henipaviruses is unknown. Here, we show that the levels of cholesterol influence the levels of NiV-induced cell-cell membrane fusion during syncytium formation and virus-cell membrane fusion during viral entry. Furthermore, the specific role of cholesterol in membrane fusion is not well defined for the paramyxoviruses. We show that the levels of cholesterol affect an early F-triggering step and a late fusion pore formation step during the membrane fusion cascade. Thus, our results expand our mechanistic understanding of the viral entry and cell-cell fusion processes, which may aid the development of antivirals.
胆固醇与多种包膜病毒的不同生命周期步骤有关，包括病毒进入宿主细胞、细胞融合以及感染细胞的病毒出芽。包膜病毒从宿主细胞中获取其膜。尽管胆固醇与各种包膜病毒进入细胞的结合和进入有关，但胆固醇在病毒-细胞膜融合过程中的确切功能在很大程度上仍然难以捉摸，特别是对于副粘病毒。此外，副粘病毒融合发生在宿主细胞膜上，对于病毒进入（病毒-细胞融合）和合胞体形成（细胞-细胞融合）都是必不可少的，这是病毒致病性的核心。尼帕病毒（NiV）是丝状病毒科的一种致命成员，该科还包括亨德拉、麻疹、腮腺炎、人类副流感病毒和各种兽医病毒。人畜共患的尼帕病毒会导致严重的脑炎、血管病变和呼吸道症状，导致人类死亡率很高。我们使用尼帕病毒作为模型来研究膜胆固醇在副粘病毒膜融合中的作用。我们使用甲基-β环糊精（MβCD）、洛伐他汀和胆固醇的组合，在细胞毒性浓度之外耗尽或富集细胞膜胆固醇。我们发现细胞细胞膜胆固醇的水平与诱导的细胞-细胞融合水平直接相关。这些表型与使用尼帕病毒/水疱性口炎病毒（VSV）假型病毒感染测定平行。值得注意的是，我们的机制研究表明，胆固醇降低了早期 F 触发步骤，但增强了尼帕病毒膜融合级联中的晚期融合孔形成步骤。因此，我们的结果扩展了我们对副粘病毒/亨德拉病毒进入和细胞-细胞融合过程的机制理解。胆固醇与不同包膜病毒的病毒生命周期的各个步骤有关。尼帕病毒（NiV）是丝状病毒科中的一种高度致病性包膜病毒，属于副粘病毒科，能够导致人类高死亡率和家养和农业重要动物的高发病率。胆固醇对 NiV 或亨德拉病毒的作用尚不清楚。在这里，我们表明胆固醇的水平会影响合胞体形成过程中 NiV 诱导的细胞-细胞膜融合水平以及病毒-细胞膜融合过程中的病毒进入水平。此外，胆固醇在副粘病毒中的膜融合具体作用尚未得到很好的定义。我们表明，胆固醇的水平会影响膜融合级联中的早期 F 触发步骤和晚期融合孔形成步骤。因此，我们的结果扩展了我们对病毒进入和细胞-细胞融合过程的机制理解，这可能有助于开发抗病毒药物。
