Target Membrane Cholesterol Modulates Single Influenza Virus Membrane Fusion Efficiency but Not Rate. 2020

Katherine N Liu, and Steven G Boxer
Department of Chemistry, Stanford University, Stanford, California.

Host lipid composition influences many stages of the influenza A virus (IAV) entry process, including initial binding of IAV to sialylated glycans, fusion between the viral envelope and the host membrane, and the formation of a fusion pore through which the viral genome is transferred into a target cell. In particular, target membrane cholesterol has been shown to preferentially associate with virus receptors and alter physical properties of the membrane like fluidity and curvature. These properties affect both IAV binding and fusion, which makes it difficult to isolate the role of cholesterol in IAV fusion from receptor binding effects. Here, we develop a fusion assay that uses synthetic DNA-lipid conjugates as surrogate viral receptors to tether virions to target vesicles. To avoid the possibly perturbative effect of adding a self-quenched concentration of dye-labeled lipids to the viral membrane, we tether virions to lipid-labeled target vesicles and use fluorescence microscopy to detect individual, pH-triggered IAV membrane fusion events. Through this approach, we find that cholesterol in the target membrane enhances the efficiency of single-particle IAV lipid mixing, whereas the rate of lipid mixing is independent of cholesterol composition. We also find that the single-particle kinetics of influenza lipid mixing to target membranes with different cholesterol compositions is independent of receptor binding, suggesting that cholesterol-mediated spatial clustering of viral receptors within the target membrane does not significantly affect IAV hemifusion. These results are consistent with the hypothesis that target membrane cholesterol increases lipid mixing efficiency by altering host membrane curvature.

UI MeSH Term Description Entries
D007251 Influenza, Human An acute viral infection in humans involving the respiratory tract. It is marked by inflammation of the NASAL MUCOSA; the PHARYNX; and conjunctiva, and by headache and severe, often generalized, myalgia. Grippe,Human Flu,Human Influenza,Influenza in Humans,Influenza,Flu, Human,Human Influenzas,Influenza in Human,Influenzas,Influenzas, Human
D008561 Membrane Fusion The adherence and merging of cell membranes, intracellular membranes, or artificial membranes to each other or to viruses, parasites, or interstitial particles through a variety of chemical and physical processes. Fusion, Membrane,Fusions, Membrane,Membrane Fusions
D008566 Membranes Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures. Membrane Tissue,Membrane,Membrane Tissues,Tissue, Membrane,Tissues, Membrane
D009980 Influenza A virus The type species of the genus ALPHAINFLUENZAVIRUS that causes influenza and other diseases in humans and animals. Antigenic variation occurs frequently between strains, allowing classification into subtypes and variants. Transmission is usually by aerosol (human and most non-aquatic hosts) or waterborne (ducks). Infected birds shed the virus in their saliva, nasal secretions, and feces. Alphainfluenzavirus influenzae,Avian Orthomyxovirus Type A,FLUAV,Fowl Plague Virus,Human Influenza A Virus,Influenza Virus Type A,Influenza Viruses Type A,Myxovirus influenzae-A hominis,Myxovirus influenzae-A suis,Myxovirus pestis galli,Orthomyxovirus Type A,Orthomyxovirus Type A, Avian,Orthomyxovirus Type A, Human,Orthomyxovirus Type A, Porcine,Pestis galli Myxovirus,Fowl Plague Viruses,Influenza A viruses,Myxovirus influenzae A hominis,Myxovirus influenzae A suis,Myxovirus, Pestis galli,Myxoviruses, Pestis galli,Pestis galli Myxoviruses,Plague Virus, Fowl,Virus, Fowl Plague
D002462 Cell Membrane The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells. Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D002784 Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Epicholesterol
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D053586 Virus Internalization The entering of cells by viruses following VIRUS ATTACHMENT. This is achieved by ENDOCYTOSIS, by translocation of the whole virus across the cell membrane, by direct MEMBRANE FUSION of the viral membrane with the CELL MEMBRANE, or by fusion of the membrane of infected cells with the membrane of non-infected cells causing SYNCYTIA to be formed. Viral Entry,Viral Internalization,Viral Membrane Fusion,Virus Entry,Virus Membrane Fusion,Entry, Viral,Entry, Virus,Fusion, Viral Membrane,Internalization, Viral,Internalization, Virus,Membrane Fusion, Viral

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