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Query: UMLS:C0038362 (stomatitis)
 8,852 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Interaction with excess unilamellar phosphatidylcholine (PC) vesicles resulted in depletion of as much as 90% of the cholesterol from the membrane of intact vesicular stomatitis (VS) virus. The cholesterol depletion was not significantly influenced by the proteolytic removal of virion glycoprotein spikes, but it was temperature dependent. Cholesterol depletion caused substantial reduction in anisotropy of the VS virion membrane as measured by fluorescence depolarization of the lipophilic probe 1,6-diphenyl-1,3,5-hexatriene; residual adsorbed vesicles represent a significant factor in this apparent increase in virion membrane fluidity. Interaction with PC vesicles resulted in a substantial loss of VS viral infectivity as measured by plating efficiency on L-cell monolayers. Reduction in infectivity appeared to be related to temperature-dependent depletion of virion cholesterol by PC vesicles. Interaction of VS virions with cholesterol-containing PC vesicles resulted in significantly less decline in infectivity, but attempts to restore cholesterol and infectivity to depleted VS virions were unsuccessful. Depletion of virion cholesterol apparently results through collision with PC vesicles rather than movement of cholesterol monomers or micelles through the aqueous phase, because PC vesicle-virion interaction in the presence of cholesterol oxidase did not result in substantial oxidation of translocated cholesterol.
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PMID:Interaction of vesicular stomatitis virus with lipid vesicles: depletion of cholesterol and effect on virion membrane fluidity and infectivity. 21 Dec 63

Semliki Forest virus (SFV) and many other enveloped animal viruses enter cells by a membrane fusion reaction triggered by the low pH within the endocytic pathway. In vitro, SFV fusion requires cholesterol in the target membrane, but the role of cholesterol in vivo is unknown. In this paper, the infection pathway of SFV was studied in mammalian and inset cells substantially depleted of sterol. Cholesterol-depleted cells were unaltered in their ability to bind, internalize, and acidify virus, but were blocked in SFV fusion and subsequent virus replication. Depleted cells could be infected by the cholesterol-independent vesicular stomatitis virus, which also enters cells via endocytosis and low pH-mediated fusion. The block in SFV infection was specifically reversed by cholesterol but not by cholestenone, which lacks the critical 3 beta-hydroxyl group. Cholesterol thus is central in the infection pathway of SFV, and may act in vivo to modulate infection by SFV and other pathogens.
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PMID:Cholesterol is required for infection by Semliki Forest virus. 167 72

Fusion of vesicular stomatitis virus with some cells (HELR 66, KB, and human erythrocytes, both intact and trypsinized) and liposomes made of various natural and synthetic lipids was studied with spin-labeled phospholipid. Binding of virus was assayed separately with radiolabeled and spin-labeled virus. Binding to cells and liposomes was small at neutral pH but enhanced at acidic pHs. Fusion with cells and liposomes was negligibly small at neutral pH but greatly activated at acidic pHs lower than 6.5. Activation of fusion occurred at lower pH values than enhancement of binding. Fusion occurred rapidly and efficiently, reaching a plateau at 50-80% after 3 min at 37 degrees C. Binding and fusion with cells were enhanced by pretreatment of cells with trypsin. Binding to liposomes was dependent on the head group of the phospholipid, stronger to phosphatidylserine than to phosphatidylcholine, but not much dependent on the acyl chain composition. On the other hand, cis-unsaturated acyl chains were required for the efficient fusion, but there was only a small, if any, requirement for the head group. Cholesterol enhanced the fusion further. High fusion efficiency with cis-unsaturated phospholipids cannot be ascribed to the membrane fluidity but may be related to higher tail-to-head volume ratios. Possible mode of interaction of viral G glycoprotein with phospholipid is discussed. The virus cell entry mechanism is suggested as binding to the phospholipid domain in the cell surface membranes, endocytosis, and followed by fusion with the phospholipid domain in endosomes upon acidification.
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PMID:Vesicular stomatitis virus binds and fuses with phospholipid domain in target cell membranes. 301 94

Cholesterol present in intact brush-border membrane vesicles made from rabbit small intestine is a poor substrate for cholesterol oxidase (EC 1.1.3.6, from Nocardia sp. and Nocardia erythropolis). It becomes susceptible to oxidation by the enzyme only after the addition of detergent, e.g., Triton X-100, in quantities sufficient to disrupt the membrane. This is also true for cholesterol present in bilayers of small unilamellar phosphatidylcholine or phosphatidylserine vesicles made by ultrasonication. The data presented here on intestinal brush-border membrane are in good agreement with results reported on other biological membranes, e.g., from erythrocytes and vesicular stomatitis virus, but are somewhat different from those on rat intestinal brush-border membrane. Our results on phospholipid bilayers agree well with published work on model membranes. From the work presented we conclude that, with our present understanding, cholesterol oxidase can hardly be used to probe the distribution of cholesterol in biological membranes. A prerequisite for using the enzyme successfully as such a probe would be the understanding of the factors controlling the interaction of the enzyme with its substrate cholesterol. The question under which conditions cholesterol oxidase could be useful for probing the distribution and preferred location of cholesterol in biological membranes is discussed.
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PMID:Cholesterol oxidase as a structural probe of biological membranes: its application to brush-border membrane. 345

Cholesterol was depleted from the membrane of vesicular stomatitis virus by exposing virion suspensions to serum lipoproteins enriched with phospholipids. Unlike the reaction of virions with phospholipid vesicle, nonspecific adherence of lipoproteins and exogenous lipids to the envelope of the virus was found to be minimal. The extent of cholesterol depletion was dependent upon the type of phospholipid complexed with interacting lipoprotein; sphingomyelin and dipalmitoyllecithin were found to be highly effective depleters of cholesterol compared to egg phosphatidylcholine, phosphatidylethanolamine, or phosphatidylserine. Similar depletion of cholesterol from the virion membrane was also observed when vesicular stomatitis virus was exposed to a complex of poly(vinylpyrrolidone) and bovine serum albumin coated with egg phosphatidylcholine or dioleoylphosphatidylcholine. Cholesterol depletion was found to alter the morphology but not the membrane integrity of the virus. Directly correlated with depletion of cholesterol was a substantial loss in the anisotropy of the viral membrane as determined by fluorescence depolarization of the lipophilic probe 1,6-diphenyl-1,3,5-hexatriene. Interaction with poly(vinylpyrrolidone) complexed with albumin, phosphatidylcholine, and cholesterol resulted in exchange of cholesterol from the virion membrane which following biphasic kinetics with a rapid and a slow phase; these data indicate that 75-85% of viral membrane cholesterol is present in the outer monolayer, and 15-25% is located in the inner monolayer. Depletion of cholesterol from the virion membrane resulted in a significant drop in the infectivity of the virus as measured by plating efficiency on L-cell monolayers. Such an effect was not observed when virion cholesterol was exchanged without net reduction in the concentration of viral membrane cholesterol. Part of the loss in infectivity following depletion of cholesterol could be restored by reincorporation of cholesterol in the membrane, thus demonstrating that membrane cholesterol partly contributes to the infectivity of vesicular stomatitis virus.
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PMID:Depletion and exchange of cholesterol from the membrane of vesicular stomatitis virus by interaction with serum lipoproteins or poly(vinylpyrrolidone) complexed with bovine serum albumin. 626 Jan 33

The enveloped alphavirus Semliki Forest virus (SFV) infects cells via a membrane fusion reaction triggered by low pH. For fusion to occur cholesterol is required in the target membrane, as demonstrated both in in vitro fusion assays and in vivo for virus infection of a host cell. In this paper we examine the role of cholesterol in postfusion events in the SFV life cycle. Cholesterol-depleted insect cells were transfected with SFV RNA or infected at very high multiplicities to circumvent the fusion block caused by the absence of cholesterol. Under these conditions, the viral spike proteins were synthesized and transported to the site of p62 cleavage with normal kinetics. Surprisingly, the subsequent exit of virus particles was dramatically slowed compared to cholesterol-containing cells. The inhibition of virus production could be reversed by the addition of cholesterol to depleted cells. In contrast to results with SFV, no cholesterol requirement for virus exit was observed for the production of either the unrelated vesicular stomatitis virus or a cholesterol-independent SFV fusion mutant. Thus, cholesterol was only critical in the exit pathway of viruses that also require cholesterol for fusion. These results demonstrate a specific and unexpected lipid requirement in virus exit, and suggest that in addition to its role in fusion, cholesterol is involved in the assembly or budding of SFV.
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PMID:Cholesterol is required in the exit pathway of Semliki Forest virus. 840 5

During the budding of enveloped viruses from the plasma membrane, the lipids are not randomly incorporated into the envelope, but virions seem to have a lipid composition different from the host membrane. Here, we have analyzed lipid assemblies in three different viruses: fowl plague virus (FPV) from the influenza virus family, vesicular stomatitis virus (VSV), and Semliki Forest virus (SFV). Analysis of detergent extractability of proteins, cholesterol, phosphoglycerolipids, and sphingomyelin in virions showed that FPV contains high amounts of detergent-insoluble complexes, whereas such complexes are largely absent from VSV or SFV. Cholesterol depletion from the viral envelope by methyl-beta-cyclodextrin results in increased solubility of sphingomyelin and of the glycoproteins in the FPV envelope. This biochemical behavior suggests that so-called raft-lipid domains are selectively incorporated into the influenza virus envelope. The "fluidity" of the FPV envelope, as measured by the fluorescence polarization of diphenylhexatriene, was significantly lower than compared with VSV or SFV. Furthermore, influenza virus hemagglutinin incorporated into the envelope of recombinant VSV was largely detergent-soluble, indicating the depletion of raft-lipid assemblies from this membrane. The results provide a model for lipid selectivity during virus budding and support the view of lipid rafts as cholesterol-dependent, ordered domains in biological membranes.
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PMID:Influenza viruses select ordered lipid domains during budding from the plasma membrane. 989 Sep 62

The membrane of human immunodeficiency virus type 1 (HIV-1) virions contains high levels of cholesterol and sphingomyelin, an enrichment that is explained by the preferential budding of the virus through raft microdomains of the plasma membrane. Upon depletion of cholesterol from HIV-1 virions with methyl-beta-cyclodextrin, infectivity was almost completely abolished. In contrast, this treatment had only a mild effect on the infectiousness of particles pseudotyped with the G envelope of vesicular stomatitis virus. The cholesterol-chelating compound nystatin had a similar effect. Cholesterol-depleted HIV-1 virions exhibited wild-type patterns of viral proteins and contained normal levels of cyclophilin A and glycosylphosphatidylinositol-anchored proteins. Nevertheless, and although they could still bind target cells, these virions were markedly defective for internalization. These results indicate that the cholesterol present in the HIV-1 membrane plays a prominent role in the fusion process that is key to viral entry and suggest that drugs capable of disturbing the lipid composition of virions could serve as a basis for the development of microbicides.
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PMID:Role for human immunodeficiency virus type 1 membrane cholesterol in viral internalization. 1223 12

Although cholesterol is synthesized in the endoplasmic reticulum (ER), compared with other cellular membranes, ER membrane has low cholesterol (3-6%). Most of the molecular machinery that regulates cellular cholesterol homeostasis also resides in the ER. Little is known about how cholesterol itself affects the ER membrane. Here, we demonstrate that acute cholesterol depletion in ER membranes impairs ER-to-Golgi transport of secretory membrane proteins. Cholesterol depletion is achieved by a brief inhibition of cholesterol synthesis with statins in cells grown in cholesterol-depleted medium. We provide evidence that secretory membrane proteins vesicular stomatitis virus glycoprotein and scavenger receptor A failed to be efficiently transported from the ER upon cholesterol depletion. Fluorescence photobleaching recovery experiments indicated that cholesterol depletion by statins leads to a severe loss of lateral mobility on the ER membrane of these transmembrane proteins, but not loss of mobility of proteins in the ER lumen. This impaired lateral mobility is correlated with impaired ER-to-Golgi transport. These results provide evidence for the first time that cholesterol is required in the ER membrane to maintain mobility of membrane proteins and thus protein secretion.
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PMID:Cholesterol is required for efficient endoplasmic reticulum-to-Golgi transport of secretory membrane proteins. 1645 37

Dystroglycan (DG) is an extracellular matrix receptor necessary for the development of metazoans from flies to humans and is also an entry route for various pathogens. Lymphocytic choriomeningitis virus (LCMV), a member of the family Arenaviridae, infects by binding to alpha-DG. Here, the role of cholesterol lipid rafts in infection by LCMV via alpha-DG was investigated. The cholesterol-sequestering drugs methyl-beta-cyclodextrin (MbetaCD), filipin and nystatin inhibited the infectivity of LCMV selectively, but did not affect infection by vesicular stomatitis virus. Cholesterol loading after depletion with MbetaCD restored infectivity to control levels. DG was not found in lipid rafts identified with the raft marker ganglioside GM1. Treatment with MbetaCD, however, enhanced the solubility of DG. This may reflect the association of DG with cholesterol outside lipid rafts and suggests that association of DG with non-raft cholesterol is critical for infection by LCMV through alpha-DG.
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PMID:Role of non-raft cholesterol in lymphocytic choriomeningitis virus infection via alpha-dystroglycan. 1647 90


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