Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038362 (stomatitis)
 8,852 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ebola virus causes hemorrhagic fever in humans and nonhuman primates, resulting in mortality rates of up to 90%. Studies of this virus have been hampered by its extraordinary pathogenicity, which requires biosafety level 4 containment. To circumvent this problem, we developed a novel complementation system for functional analysis of Ebola virus glycoproteins. It relies on a recombinant vesicular stomatitis virus (VSV) that contains the green fluorescent protein gene instead of the receptor-binding G protein gene (VSVDeltaG*). Herein we show that Ebola Reston virus glycoprotein (ResGP) is efficiently incorporated into VSV particles. This recombinant VSV with integrated ResGP (VSVDeltaG*-ResGP) infected primate cells more efficiently than any of the other mammalian or avian cells examined, in a manner consistent with the host range tropism of Ebola virus, whereas VSVDeltaG* complemented with VSV G protein (VSVDeltaG*-G) efficiently infected the majority of the cells tested. We also tested the utility of this system for investigating the cellular receptors for Ebola virus. Chemical modification of cells to alter their surface proteins markedly reduced their susceptibility to VSVDeltaG*-ResGP but not to VSVDeltaG*-G. These findings suggest that cell surface glycoproteins with N-linked oligosaccharide chains contribute to the entry of Ebola viruses, presumably acting as a specific receptor and/or cofactor for virus entry. Thus, our VSV system should be useful for investigating the functions of glycoproteins from highly pathogenic viruses or those incapable of being cultured in vitro.
 ...
PMID:A system for functional analysis of Ebola virus glycoprotein. 940 87

Marburg virus, a filovirus, causes severe hemorrhagic fever with hitherto poorly understood molecular pathogenesis. We have investigated here the vectorial transport of the surface protein GP of Marburg virus in polarized epithelial cells. To this end, we established an MDCKII cell line that was able to express GP permanently (MDCK-GP). The functional integrity of GP expressed in these cells was analyzed using vesicular stomatitis virus pseudotypes. Further experiments revealed that GP is transported in MDCK-GP cells mainly to the apical membrane and is released exclusively into the culture medium facing the apical membrane. When MDCKII cells were infected with Marburg virus, the majority of GP was also transported to the apical membrane, suggesting that the protein contains an autonomous apical transport signal. Release of infectious progeny virions, however, took place exclusively at the basolateral membrane of the cells. Thus, vectorial budding of Marburg virus is presumably determined by factors other than the surface protein.
 ...
PMID:Sorting of Marburg virus surface protein and virus release take place at opposite surfaces of infected polarized epithelial cells. 1115

Ebola virus causes severe hemorrhagic fever in primates, resulting in mortality rates of up to 100%, yet there are no satisfactory biologic explanations for this extreme virulence. Here we show that antisera produced by DNA immunization with a plasmid encoding the surface glycoprotein (GP) of the Zaire strain of Ebola virus enhances the infectivity of vesicular stomatitis virus pseudotyped with the GP. Substantially weaker enhancement was observed with antiserum to the GP of the Reston strain, which is much less pathogenic in humans than the Ebola Zaire and Sudan viruses. The enhancing activity was abolished by heat but was increased in the presence of complement system inhibitors, suggesting that heat-labile factors other than the complement system are required for this effect. We also generated an anti-Zaire GP monoclonal antibody that enhanced viral infectivity and another that neutralized it, indicating the presence of distinct epitopes for these properties. Our findings suggest that antibody-dependent enhancement of infectivity may account for the extreme virulence of the virus. They also raise issues about the development of Ebola virus vaccines and the use of passive prophylaxis or therapy with Ebola virus GP antibodies.
 ...
PMID:Infectivity-enhancing antibodies to Ebola virus glycoprotein. 1116 Jul 35

Ebola virus causes lethal hemorrhagic fever in humans, but currently there are no effective vaccines or antiviral compounds for this infectious disease. Passive transfer of monoclonal antibodies (MAbs) protects mice from lethal Ebola virus infection (J. A. Wilson, M. Hevey, R. Bakken, S. Guest, M. Bray, A. L. Schmaljohn, and M. K. Hart, Science 287:1664-1666, 2000). However, the epitopes responsible for neutralization have been only partially characterized because some of the MAbs do not recognize the short synthetic peptides used for epitope mapping. To identify the amino acids recognized by neutralizing and protective antibodies, we generated a recombinant vesicular stomatitis virus (VSV) containing the Ebola virus glycoprotein-encoding gene instead of the VSV G protein-encoding gene and used it to select escape variants by growing it in the presence of a MAb (133/3.16 or 226/8.1) that neutralizes the infectivity of the virus. All three variants selected by MAb 133/3.16 contained a single amino acid substitution at amino acid position 549 in the GP2 subunit. By contrast, MAb 226/8.1 selected three different variants containing substitutions at positions 134, 194, and 199 in the GP1 subunit, suggesting that this antibody recognized a conformational epitope. Passive transfer of each of these MAbs completely protected mice from a lethal Ebola virus infection. These data indicate that neutralizing antibody cocktails for passive prophylaxis and therapy of Ebola hemorrhagic fever can reduce the possibility of the emergence of antigenic variants in infected individuals.
 ...
PMID:Identification of protective epitopes on ebola virus glycoprotein at the single amino acid level by using recombinant vesicular stomatitis viruses. 1250 22

A vesicular stomatitis virus (VSV) pseudotype bearing hantavirus envelope glycoproteins was produced and used in a neutralization test as a substitute for native hantavirus. The recombinant VSV, in which the enveloped protein gene (G) was replaced by the green fluorescent protein gene and complemented with G protein expressed in trans (VSVDeltaG*G), was kindly provided by M. A. Whitt. 293T cells were transfected with plasmids for the expression of envelope glycoproteins (G1 and G2) of HTNV or SEOV and were then infected with VSVDeltaG*G. Pseudotype VSV with the Hantaan (VSVDeltaG*-HTN) or Seoul (VSVDeltaG*-SEO) envelope glycoproteins were harvested from the culture supernatant. The number of infectious units (IU) of the pseudotype VSVs ranged from 10(5) to 10(6)/ml. The infectivity of VSVDeltaG*-HTN and VSVDeltaG*-SEO was neutralized with monoclonal antibodies, immune rabbit sera, and sera from patients with hemorrhagic fever with renal syndrome, and the neutralizing titers were similar to those obtained with native hantaviruses. These results show that VSVDeltaG*-HTN and -SEO can be used as a rapid, specific, and safe neutralization test for detecting hantavirus-neutralizing antibodies as an effective substitute for the use of native hantaviruses. Furthermore, the IU of VSVDeltaG*-HTN and -SEO did not decrease by more than 10-fold when stored at 4 degrees C for up to 30 days. The stability of the pseudotype viruses allows distribution of the material to remote areas by using conventional cooling boxes for use as a diagnostic reagent.
 ...
PMID:Use of vesicular stomatitis virus pseudotypes bearing hantaan or seoul virus envelope proteins in a rapid and safe neutralization test. 1252 53

Replication-competent recombinant vesicular stomatitis viruses (rVSVs) expressing the type I transmembrane glycoproteins and selected soluble glycoproteins of several viral hemorrhagic fever agents (Marburg virus, Ebola virus, and Lassa virus) were generated and characterized. All recombinant viruses exhibited rhabdovirus morphology and replicated cytolytically in tissue culture. Unlike the rVSVs with an additional transcription unit expressing the soluble glycoproteins, the viruses carrying the foreign transmembrane glycoproteins in replacement of the VSV glycoprotein were slightly attenuated in growth. Biosynthesis and processing of the foreign glycoproteins were authentic, and the cell tropism was defined by the transmembrane glycoprotein. None of the rVSVs displayed pathogenic potential in animals. The rVSV expressing the Zaire Ebola virus transmembrane glycoprotein mediated protection in mice against a lethal Zaire Ebola virus challenge. Our data suggest that the recombinant VSV can be used to study the role of the viral glycoproteins in virus replication, immune response, and pathogenesis.
 ...
PMID:Properties of replication-competent vesicular stomatitis virus vectors expressing glycoproteins of filoviruses and arenaviruses. 1511 24

The Ebola filoviruses are aggressive pathogens that cause severe and often lethal hemorrhagic fever syndromes in humans and nonhuman primates. To date, no effective therapies have been identified. To analyze the entry and fusion properties of Ebola virus, we adapted a human immunodeficiency virus type 1 (HIV-1) virion-based fusion assay by substituting Ebola virus glycoprotein (GP) for the HIV-1 envelope. Fusion was detected by cleavage of the fluorogenic substrate CCF2 by beta-lactamase-Vpr incorporated into virions and released as a result of virion fusion. Entry and fusion induced by the Ebola virus GP occurred with much slower kinetics than with vesicular stomatitis virus G protein (VSV-G) and were blocked by depletion of membrane cholesterol and by inhibition of vesicular acidification with bafilomycin A1. These properties confirmed earlier studies and validated the assay for exploring other properties of Ebola virus GP-mediated entry and fusion. Entry and fusion of Ebola virus GP pseudotypes, but not VSV-G or HIV-1 Env pseudotypes, were impaired in the presence of the microtubule-disrupting agent nocodazole but were enhanced in the presence of the microtubule-stabilizing agent paclitaxel (Taxol). Agents that impaired microfilament function, including cytochalasin B, cytochalasin D, latrunculin A, and jasplakinolide, also inhibited Ebola virus GP-mediated entry and fusion. Together, these findings suggest that both microtubules and microfilaments may play a role in the effective trafficking of vesicles containing Ebola virions from the cell surface to the appropriate acidified vesicular compartment where fusion occurs. In terms of Ebola virus GP-mediated entry and fusion to various target cells, primary macrophages proved highly sensitive, while monocytes from the same donors displayed greatly reduced levels of entry and fusion. We further observed that tumor necrosis factor alpha, which is released by Ebola virus-infected monocytes/macrophages, enhanced Ebola virus GP-mediated entry and fusion to human umbilical vein endothelial cells. Thus, Ebola virus infection of one target cell may induce biological changes that facilitate infection of secondary target cells that play a key role in filovirus pathogenesis. Finally, these studies indicate that pseudotyping in the HIV-1 virion-based fusion assay may be a valuable approach to the study of entry and fusion properties mediated through the envelopes of other viral pathogens.
 ...
PMID:Studies of ebola virus glycoprotein-mediated entry and fusion by using pseudotyped human immunodeficiency virus type 1 virions: involvement of cytoskeletal proteins and enhancement by tumor necrosis factor alpha. 1561 20

Ebola virus (EboV) causes rapidly fatal hemorrhagic fever in humans and there is currently no effective treatment. We found that the infection of African green monkey kidney (Vero) cells by vesicular stomatitis viruses bearing the EboV glycoprotein (GP) requires the activity of endosomal cysteine proteases. Using selective protease inhibitors and protease-deficient cell lines, we identified an essential role for cathepsin B (CatB) and an accessory role for cathepsin L (CatL) in EboV GP-dependent entry. Biochemical studies demonstrate that CatB and CatL mediate entry by carrying out proteolysis of the EboV GP subunit GP1 and support a multistep mechanism that explains the relative contributions of these enzymes to infection. CatB and CatB/CatL inhibitors diminish the multiplication of infectious EboV-Zaire in cultured cells and may merit investigation as anti-EboV drugs.
 ...
PMID:Endosomal proteolysis of the Ebola virus glycoprotein is necessary for infection. 1583 16

Ever since the S-adenosylhomocysteine (AdoHcy, SAH) hydrolase was recognized as a pharmacological target for antiviral agents (J. A. Montgomery et al., J. Med. Chem. 25:626-629, 1982), an increasing number of adenosine, acyclic adenosine, and carbocyclic adenosine analogues have been described as potent SAH hydrolase inhibitors endowed with broad-spectrum antiviral activity. The antiviral activity spectrum of the SAH hydrolase inhibitors include pox-, rhabdo-, filo-, arena-, paramyxo-, reo-, and retroviruses. Among the most potent SAH hydrolase inhibitors and antiviral agents rank carbocyclic 3-deazaadenosine (C-c3 Ado), neplanocin A, 3-deazaneplanocin A, the 5'-nor derivatives of carbocyclic adenosine (C-Ado, aristeromycin), and the 2-halo (i.e., 2-fluoro) and 6'-R-alkyl (i.e., 6'-R-methyl) derivatives of neplanocin A. These compounds are particularly active against poxviruses (i.e., vaccinia virus), and rhabdoviruses (i.e., vesicular stomatitis virus). The in vivo efficacy of C-c3 Ado and 3-deazaneplanocin A has been established in mouse models for vaccinia virus, vesicular stomatitis virus, and Ebola virus. SAH hydrolase inhibitors such as C-c3Ado and 3-deazaneplanocin A should in thefirst place be considered for therapeutic (or prophylactic) use against poxvirus infections, including smallpox, and hemorrhagic fever virus infections such as Ebola.
 ...
PMID:John Montgomery's legacy: carbocyclic adenosine analogues as SAH hydrolase inhibitors with broad-spectrum antiviral activity. 1643 25

The filoviruses Ebolavirus (EBOV) and Marburgvirus (MARV) cause severe hemorrhagic fever in humans and are potential agents of biological warfare. The envelope glycoprotein (GP) of filoviruses mediates viral entry into cells and is an attractive target for therapeutic intervention and vaccine design. Here, we asked if the efficiency of virion incorporation of EBOV-GP impacts attachment and entry into target cells and modulates susceptibility to neutralizing antibodies. In order to control the level of EBOV-GP expression, we generated cell lines expressing the GPs of the four known EBOV subspecies in an inducible fashion. Regulated expression of GP on the cell surface allowed production of reporter viruses harboring different amounts of GP. A pronounced reduction of virion incorporation of EBOV-GP had relatively little effect on virion infectivity, suggesting that only a few copies of GP might be sufficient for efficient engagement of cellular receptors. In contrast, optimal interactions with cellular attachment factors like the DC-SIGN protein required incorporation of high amounts of GP. Antibody-mediated neutralization of virions bearing high amounts of GP was slightly more efficient than neutralization of virions harboring low amounts of GP, suggesting that the efficiency of GP incorporation into virions might modulate susceptibility to neutralizing antibodies. Finally, regulated expression of GP in permissive 293 cells did not reduce EBOV-GP-driven infection but diminished vesicular stomatitis virus GP (VSV-G) and amphotropic murine leukemia virus (A-MLV) GP mediated entry in a dose-dependent manner. Therefore, intracellular GP does not seem to downmodulate expression of its receptor(s) but might alter expression and/or function of molecules involved in VSV-G and A-MLV-GP-dependent entry. Our results suggest that the efficiency of virion incorporation of GP could impact EBOV attachment to target cells and might modulate control of viral spread by the humoral immune response.
 ...
PMID:Modulation of virion incorporation of Ebolavirus glycoprotein: effects on attachment, cellular entry and neutralization. 1677 70


1 2 3 4 5 Next >>