42 results on '"George Savidis"'
Search Results
2. Biographical Note
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
3. Appendix
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
4. Cover Page
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
5. 1932
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
6. Editor's Introduction To The Notes
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
7. Alphabetical Index Of Titles
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
8. The Lockert Library of Poetry in Translation
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
9. Unpublished Poems
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
10. Published Poems
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
11. Half-title Page, Title Page
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
12. Before 1911
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
13. Contents
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
14. Translators' Foreword To The Revised Edition
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
15. Copyright Page, Dedication
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C. P. Cavafy, George Savidis, Edmund Keeley, and Philip Sherrard
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- 2020
16. Identification of Zika Virus and Dengue Virus Dependency Factors using Functional Genomics
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George Savidis, William M. McDougall, Paul Meraner, Jill M. Perreira, Jocelyn M. Portmann, Gaia Trincucci, Sinu P. John, Aaron M. Aker, Nicholas Renzette, Douglas R. Robbins, Zhiru Guo, Sharone Green, Timothy F. Kowalik, and Abraham L. Brass
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Zika virus ,dengue virus ,yellow fever virus ,flavivirus ,arbovirus ,EMC ,AXL ,CRISPR/Cas9 screen ,MORR ,RNAi screen ,Biology (General) ,QH301-705.5 - Abstract
The flaviviruses dengue virus (DENV) and Zika virus (ZIKV) are severe health threats with rapidly expanding ranges. To identify the host cell dependencies of DENV and ZIKV, we completed orthologous functional genomic screens using RNAi and CRISPR/Cas9 approaches. The screens recovered the ZIKV entry factor AXL as well as multiple host factors involved in endocytosis (RAB5C and RABGEF), heparin sulfation (NDST1 and EXT1), and transmembrane protein processing and maturation, including the endoplasmic reticulum membrane complex (EMC). We find that both flaviviruses require the EMC for their early stages of infection. Together, these studies generate a high-confidence, systems-wide view of human-flavivirus interactions and provide insights into the role of the EMC in flavivirus replication.
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- 2016
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- View/download PDF
17. The IFITMs Inhibit Zika Virus Replication
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George Savidis, Jill M. Perreira, Jocelyn M. Portmann, Paul Meraner, Zhiru Guo, Sharone Green, and Abraham L. Brass
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Zika virus ,flavivirus ,host factors ,IFITM ,IFITM1 ,IFITM3 ,intrinsic immunity ,interferon ,Biology (General) ,QH301-705.5 - Abstract
Zika virus has emerged as a severe health threat with a rapidly expanding range. The IFITM family of restriction factors inhibits the replication of a broad range of viruses, including the closely related flaviruses West Nile virus and dengue virus. Here, we show that IFITM1 and IFITM3 inhibit Zika virus infection early in the viral life cycle. Moreover, IFITM3 can prevent Zika-virus-induced cell death. These results suggest that strategies to boost the actions and/or levels of the IFITMs might be useful for inhibiting a broad range of emerging viruses.
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- 2016
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18. Direct Visualization of HIV-1 Replication Intermediates Shows that Capsid and CPSF6 Modulate HIV-1 Intra-nuclear Invasion and Integration
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Christopher R. Chin, Jill M. Perreira, George Savidis, Jocelyn M. Portmann, Aaron M. Aker, Eric M. Feeley, Miles C. Smith, and Abraham L. Brass
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Biology (General) ,QH301-705.5 - Abstract
Direct visualization of HIV-1 replication would improve our understanding of the viral life cycle. We adapted established technology and reagents to develop an imaging approach, ViewHIV, which allows evaluation of early HIV-1 replication intermediates, from reverse transcription to integration. These methods permit the simultaneous evaluation of both the capsid protein (CA) and viral DNA genome (vDNA) components of HIV-1 in both the cytosol and nuclei of single cells. ViewHIV is relatively rapid, uses readily available reagents in combination with standard confocal microscopy, and can be done with virtually any HIV-1 strain and permissive cell lines or primary cells. Using ViewHIV, we find that CA enters the nucleus and associates with vDNA in both transformed and primary cells. We also find that CA’s interaction with the host polyadenylation factor, CPSF6, enhances nuclear entry and potentiates HIV-1’s depth of nuclear invasion, potentially aiding the virus’s integration into gene-dense regions.
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- 2015
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19. RNASEK Is a V-ATPase-Associated Factor Required for Endocytosis and the Replication of Rhinovirus, Influenza A Virus, and Dengue Virus
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Jill M. Perreira, Aaron M. Aker, George Savidis, Christopher R. Chin, William M. McDougall, Jocelyn M. Portmann, Paul Meraner, Miles C. Smith, Motiur Rahman, Richard E. Baker, Annick Gauthier, Michael Franti, and Abraham L. Brass
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Biology (General) ,QH301-705.5 - Abstract
Human rhinovirus (HRV) causes upper respiratory infections and asthma exacerbations. We screened multiple orthologous RNAi reagents and identified host proteins that modulate HRV replication. Here, we show that RNASEK, a transmembrane protein, was needed for the replication of HRV, influenza A virus, and dengue virus. RNASEK localizes to the cell surface and endosomal pathway and closely associates with the vacuolar ATPase (V-ATPase) proton pump. RNASEK is required for endocytosis, and its depletion produces enlarged clathrin-coated pits (CCPs) at the cell surface. These enlarged CCPs contain endocytic cargo and are bound by the scissioning GTPase, DNM2. Loss of RNASEK alters the localization of multiple V-ATPase subunits and lowers the levels of the ATP6AP1 subunit. Together, our results show that RNASEK closely associates with the V-ATPase and is required for its function; its loss prevents the early events of endocytosis and the replication of multiple pathogenic viruses.
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- 2015
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20. Amphotericin B Increases Influenza A Virus Infection by Preventing IFITM3-Mediated Restriction
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Tsai-Yu Lin, Christopher R. Chin, Aaron R. Everitt, Simon Clare, Jill M. Perreira, George Savidis, Aaron M. Aker, Sinu P. John, David Sarlah, Erick M. Carreira, Stephen J. Elledge, Paul Kellam, and Abraham L. Brass
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Biology (General) ,QH301-705.5 - Abstract
The IFITMs inhibit influenza A virus (IAV) replication in vitro and in vivo. Here, we establish that the antimycotic heptaen, amphotericin B (AmphoB), prevents IFITM3-mediated restriction of IAV, thereby increasing viral replication. Consistent with its neutralization of IFITM3, a clinical preparation of AmphoB, AmBisome, reduces the majority of interferon’s protective effect against IAV in vitro. Mechanistic studies reveal that IFITM1 decreases host-membrane fluidity, suggesting both a possible mechanism for IFITM-mediated restriction and its negation by AmphoB. Notably, we reveal that mice treated with AmBisome succumbed to a normally mild IAV infection, similar to animals deficient in Ifitm3. Therefore, patients receiving antifungal therapy with clinical preparations of AmphoB may be functionally immunocompromised and thus more vulnerable to influenza, as well as other IFITM3-restricted viral infections.
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- 2013
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21. IFITM3 restricts influenza A virus entry by blocking the formation of fusion pores following virus-endosome hemifusion.
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Tanay M Desai, Mariana Marin, Christopher R Chin, George Savidis, Abraham L Brass, and Gregory B Melikyan
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Immunologic diseases. Allergy ,RC581-607 ,Biology (General) ,QH301-705.5 - Abstract
Interferon-induced transmembrane proteins (IFITMs) inhibit infection of diverse enveloped viruses, including the influenza A virus (IAV) which is thought to enter from late endosomes. Recent evidence suggests that IFITMs block virus hemifusion (lipid mixing in the absence of viral content release) by altering the properties of cell membranes. Consistent with this mechanism, excess cholesterol in late endosomes of IFITM-expressing cells has been reported to inhibit IAV entry. Here, we examined IAV restriction by IFITM3 protein using direct virus-cell fusion assay and single virus imaging in live cells. IFITM3 over-expression did not inhibit lipid mixing, but abrogated the release of viral content into the cytoplasm. Although late endosomes of IFITM3-expressing cells accumulated cholesterol, other interventions leading to aberrantly high levels of this lipid did not inhibit virus fusion. These results imply that excess cholesterol in late endosomes is not the mechanism by which IFITM3 inhibits the transition from hemifusion to full fusion. The IFITM3's ability to block fusion pore formation at a post-hemifusion stage shows that this protein stabilizes the cytoplasmic leaflet of endosomal membranes without adversely affecting the lumenal leaflet. We propose that IFITM3 interferes with pore formation either directly, through partitioning into the cytoplasmic leaflet of a hemifusion intermediate, or indirectly, by modulating the lipid/protein composition of this leaflet. Alternatively, IFITM3 may redirect IAV fusion to a non-productive pathway, perhaps by promoting fusion with intralumenal vesicles within multivesicular bodies/late endosomes.
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- 2014
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22. Functional Mapping of Regions Involved in the Negative Imprinting of Virion Particle Infectivity and in Target Cell Protection by Interferon-Induced Transmembrane Protein 3 against HIV-1
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Lucie Etienne, Julien Burlaud-Gaillard, George Savidis, Andrea Cimarelli, Li Zhong, Philippe Roingeard, Mathilde Delpeuch, Romain Appourchaux, Kevin Tartour, Abraham L. Brass, Interaction hôte pathogène lors de l'infection lentivirale – Host-Pathogen Interaction during Lentiviral Infection (LP2L), Centre International de Recherche en Infectiologie (CIRI), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Plateforme IBISA de Microscopie Electronique [CHRU de Tours] (UNIV Tours), Centre Hospitalier Régional Universitaire de Tours (CHRU Tours)-Université de Tours (UT), Department of Microbiology and Physiological Systems, University of Massachusetts Medical School [Worcester] (UMASS), University of Massachusetts System (UMASS)-University of Massachusetts System (UMASS), Virus, pseudo-virus: Morphogénèse et Antigénicité, Université de Tours (UT)-EA3856, Centre International de Recherche en Infectiologie - UMR (CIRI), Institut National de la Santé et de la Recherche Médicale (INSERM)-École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Centre Hospitalier Régional Universitaire de Tours (CHRU TOURS)-Université de Tours, and Université de Tours-EA3856
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Endosome ,Immunology ,Mutant ,Cellular Response to Infection ,Context (language use) ,Endosomes ,Biology ,Microbiology ,Virus ,03 medical and health sciences ,Protein Domains ,Interferon ,Virology ,medicine ,Humans ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,Infectivity ,0303 health sciences ,Protein Stability ,Tetraspanin 30 ,Virus Assembly ,030302 biochemistry & molecular biology ,Virion ,Membrane Proteins ,RNA-Binding Proteins ,Transmembrane protein ,3. Good health ,Cell biology ,Cholesterol ,HEK293 Cells ,Insect Science ,Mutation ,[SDV.MP.VIR]Life Sciences [q-bio]/Microbiology and Parasitology/Virology ,HIV-1 ,Intracellular ,HeLa Cells ,medicine.drug - Abstract
The interferon-induced transmembrane proteins (IFITMs) are a family of highly related antiviral factors that affect numerous viruses at two steps: in target cells by sequestering incoming viruses in endosomes and in producing cells by leading to the production of virions that package IFITMs and exhibit decreased infectivity. While most studies have focused on the former, little is known about the regulation of the negative imprinting of virion particle infectivity by IFITMs and about its relationship with target cell protection. Using a panel of IFITM3 mutants against HIV-1, we have explored these issues as well as others related to the biology of IFITM3, in particular virion packaging, stability, the relation to CD63/multivesicular bodies (MVBs), the modulation of cholesterol levels, and the relationship between negative imprinting of virions and target cell protection. The results that we have obtained exclude a role for cholesterol and indicate that CD63 accumulation does not directly relate to an antiviral behavior. We have defined regions that modulate the two antiviral properties of IFITM3 as well as novel domains that modulate protein stability and that, in so doing, influence the extent of its packaging into virions. The results that we have obtained, however, indicate that, even in the context of an IFITM-susceptible virus, IFITM3 packaging is not sufficient for negative imprinting. Finally, while most mutations concomitantly affect target cell protection and negative imprinting, a region in the C-terminal domain (CTD) exhibits a differential behavior, potentially highlighting the regulatory role that this domain may play in the two antiviral activities of IFITM3. IMPORTANCE IFITM proteins have been associated with the sequestration of incoming virions in endosomes (target cell protection) and with the production of virion particles that incorporate IFITMs and exhibit decreased infectivity (negative imprinting of virion infectivity). How the latter is regulated and whether these two antiviral properties are related remain unknown. By examining the behavior of a large panel of IFITM3 mutants against HIV-1, we determined that IFITM3 mutants are essentially packaged into virions proportionally to their intracellular levels of expression. However, even in the context of an IFITM-susceptible virus, IFITM3 packaging is not sufficient for the antiviral effects. Most mutations were found to concomitantly affect both antiviral properties of IFITM3, but one CTD mutant exhibited a divergent behavior, possibly highlighting a novel regulatory role for this domain. These findings thus advance our comprehension of how this class of broad antiviral restriction factors acts.
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- 2019
23. Identification of Zika Virus and Dengue Virus Dependency Factors using Functional Genomics
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Sinu P. John, William M. McDougall, Jocelyn M. Portmann, Abraham L. Brass, Sharone Green, Jill M. Perreira, George Savidis, Zhiru Guo, Paul Meraner, Douglas Robbins, Gaia Trincucci, Timothy F. Kowalik, Aaron M. Aker, and Nicholas Renzette
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0301 basic medicine ,viruses ,Biology ,Dengue virus ,Endoplasmic Reticulum ,Virus Replication ,medicine.disease_cause ,Arbovirus ,General Biochemistry, Genetics and Molecular Biology ,Zika virus ,03 medical and health sciences ,0302 clinical medicine ,flavivirus ,CRISPR/Cas9 screen ,RNA interference ,EMC ,medicine ,Humans ,CRISPR ,Genetic Testing ,Protein Interaction Maps ,lcsh:QH301-705.5 ,MORR ,yellow fever virus ,RNAi screen ,Cell Membrane ,AXL ,virus diseases ,Genomics ,Intracellular Membranes ,Zika Virus ,Dengue Virus ,biochemical phenomena, metabolism, and nutrition ,medicine.disease ,biology.organism_classification ,Virology ,Flavivirus ,arbovirus ,030104 developmental biology ,lcsh:Biology (General) ,Viral replication ,Host-Pathogen Interactions ,RNA Interference ,CRISPR-Cas Systems ,Functional genomics ,030217 neurology & neurosurgery ,HeLa Cells ,Protein Binding - Abstract
SummaryThe flaviviruses dengue virus (DENV) and Zika virus (ZIKV) are severe health threats with rapidly expanding ranges. To identify the host cell dependencies of DENV and ZIKV, we completed orthologous functional genomic screens using RNAi and CRISPR/Cas9 approaches. The screens recovered the ZIKV entry factor AXL as well as multiple host factors involved in endocytosis (RAB5C and RABGEF), heparin sulfation (NDST1 and EXT1), and transmembrane protein processing and maturation, including the endoplasmic reticulum membrane complex (EMC). We find that both flaviviruses require the EMC for their early stages of infection. Together, these studies generate a high-confidence, systems-wide view of human-flavivirus interactions and provide insights into the role of the EMC in flavivirus replication.
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- 2016
24. PREFACE
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Edmund Keeley and George Savidis
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- 2017
25. The CD225 Domain of IFITM3 Is Required for both IFITM Protein Association and Inhibition of Influenza A Virus and Dengue Virus Replication
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Thomas Pertel, Stephen J. Elledge, Andrew E. H. Elia, Mehul Vora, Sarah E. Smith, Eric M. Feeley, Aaron M. Aker, George Savidis, Sinu P. John, Christopher R. Chin, Jill M. Perreira, Paul Kellam, Abraham L. Brass, and Aaron R. Everitt
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DNA, Complementary ,DNA Mutational Analysis ,Immunoblotting ,Molecular Sequence Data ,Immunology ,Cell Culture Techniques ,Biology ,Dengue virus ,medicine.disease_cause ,Virus Replication ,Models, Biological ,Polymorphism, Single Nucleotide ,Microbiology ,Mass Spectrometry ,Conserved sequence ,Madin Darby Canine Kidney Cells ,Protein structure ,Dogs ,Virology ,Influenza A virus ,medicine ,Animals ,Humans ,Immunoprecipitation ,Amino Acid Sequence ,Cloning, Molecular ,Gene ,Conserved Sequence ,Microscopy, Confocal ,Membrane Proteins ,RNA-Binding Proteins ,Dengue Virus ,Transmembrane protein ,Protein Structure, Tertiary ,Virus-Cell Interactions ,HEK293 Cells ,Viral replication ,Membrane protein ,Insect Science ,HeLa Cells - Abstract
The interferon-induced transmembrane protein 3 (IFITM3) gene is an interferon-stimulated gene that inhibits the replication of multiple pathogenic viruses in vitro and in vivo . IFITM3 is a member of a large protein superfamily, whose members share a functionally undefined area of high amino acid conservation, the CD225 domain. We performed mutational analyses of IFITM3 and identified multiple residues within the CD225 domain, consisting of the first intramembrane domain (intramembrane domain 1 [IM1]) and a conserved intracellular loop (CIL), that are required for restriction of both influenza A virus (IAV) and dengue virus (DENV) infection in vitro . Two phenylalanines within IM1 (F75 and F78) also mediate a physical association between IFITM proteins, and the loss of this interaction decreases IFITM3-mediated restriction. By extension, similar IM1-mediated associations may contribute to the functions of additional members of the CD225 domain family. IFITM3's distal N-terminal domain is also needed for full antiviral activity, including a tyrosine (Y20), whose alteration results in mislocalization of a portion of IFITM3 to the cell periphery and surface. Comparative analyses demonstrate that similar molecular determinants are needed for IFITM3's restriction of both IAV and DENV. However, a portion of the CIL including Y99 and R87 is preferentially needed for inhibition of the orthomyxovirus. Several IFITM3 proteins engineered with rare single-nucleotide polymorphisms demonstrated reduced expression or mislocalization, and these events were associated with enhanced viral replication in vitro , suggesting that possessing such alleles may impact an individual's risk for viral infection. On the basis of this and other data, we propose a model for IFITM3-mediated restriction.
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- 2013
- Full Text
- View/download PDF
26. Comparative study of systemic intravenous and regional intravenous administration of prophylactic antibiotic in lower extremity orthopaedic surgery
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Konstantinos Kesoglou, Stefanos Tsourvakas, Christos Alexandropoulos, Cleanthes Efstathiou, Helen Polizou, and George Savidis
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Prophylactic antibiotic ,Ceforanide ,Tourniquet ,medicine.medical_specialty ,Reconstructive surgery ,business.industry ,medicine.drug_class ,Antibiotics ,Cephalosporin ,Surgery ,Anesthesia ,Orthopedic surgery ,Medicine ,Orthopedics and Sports Medicine ,Antibiotic prophylaxis ,business ,medicine.drug - Abstract
In this study, we describe a technique for the delivery of regional antibiotic prophylaxis in patients undergoing reconstructive surgery in the lower extremities and compare the tissue antibiotic concentrations achieved by this technique with those achieved by standard systemic intravenous prophylaxis. The efficacy of a regional route for antibiotic prophylaxis in lower extremity orthopaedic procedures was investigated in 20 patients and compared with the standard systemic intravenous method in 45 patients using a second generation cephalosporin (ceforanide). The antibiotic (2 g) was given intravenously as the standard systemic prophylaxis at different intervals (10, 20 min and 2 h) before tourniquet inflation. The same dose of antibiotic was injected intravenously into the ipsilateral foot after the inflation of tourniquet. Samples of bone, fat and muscle were collected during the operation and assayed for ceforanide by a microbiological method. None of the patients experienced local or systemic adverse following the regional administration of ceforanide, or infections during the postoperative and follow-up period. Peak tissue levels of the systemic antibiotic were observed when the antibiotic was given 20 min before tourniquet inflation. For all tissue samples, the antibiotic levels were significantly higher when the antibiotic was given regionally (P < 0.001). The results of this study suggest that the regional administration could be a useful route for prophylaxis during lower extremity orthopaedic procedures when they are carried out under tourniquet control.
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- 2009
27. IFITM3 restricts influenza A virus entry by blocking the formation of fusion pores following virus-endosome hemifusion
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Mariana Marin, George Savidis, Abraham L. Brass, Christopher R. Chin, Gregory B. Melikyan, and Tanay M. Desai
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lcsh:Immunologic diseases. Allergy ,Endosome ,Immunology ,Biophysics ,CHO Cells ,Endosomes ,Biology ,Membrane Fusion ,Microbiology ,Virus ,Cricetulus ,Viral envelope ,Cricetinae ,Virology ,Molecular Cell Biology ,Influenza, Human ,Genetics ,Animals ,Humans ,Molecular Biology ,lcsh:QH301-705.5 ,Cell fusion ,Vesicle ,Biology and Life Sciences ,Membrane Proteins ,RNA-Binding Proteins ,Lipid bilayer fusion ,Cell Biology ,Virus Internalization ,Transmembrane protein ,Cell biology ,Cholesterol ,HEK293 Cells ,lcsh:Biology (General) ,Influenza A virus ,Cytoplasm ,Parasitology ,lipids (amino acids, peptides, and proteins) ,lcsh:RC581-607 ,Research Article - Abstract
Interferon-induced transmembrane proteins (IFITMs) inhibit infection of diverse enveloped viruses, including the influenza A virus (IAV) which is thought to enter from late endosomes. Recent evidence suggests that IFITMs block virus hemifusion (lipid mixing in the absence of viral content release) by altering the properties of cell membranes. Consistent with this mechanism, excess cholesterol in late endosomes of IFITM-expressing cells has been reported to inhibit IAV entry. Here, we examined IAV restriction by IFITM3 protein using direct virus-cell fusion assay and single virus imaging in live cells. IFITM3 over-expression did not inhibit lipid mixing, but abrogated the release of viral content into the cytoplasm. Although late endosomes of IFITM3-expressing cells accumulated cholesterol, other interventions leading to aberrantly high levels of this lipid did not inhibit virus fusion. These results imply that excess cholesterol in late endosomes is not the mechanism by which IFITM3 inhibits the transition from hemifusion to full fusion. The IFITM3's ability to block fusion pore formation at a post-hemifusion stage shows that this protein stabilizes the cytoplasmic leaflet of endosomal membranes without adversely affecting the lumenal leaflet. We propose that IFITM3 interferes with pore formation either directly, through partitioning into the cytoplasmic leaflet of a hemifusion intermediate, or indirectly, by modulating the lipid/protein composition of this leaflet. Alternatively, IFITM3 may redirect IAV fusion to a non-productive pathway, perhaps by promoting fusion with intralumenal vesicles within multivesicular bodies/late endosomes., Author Summary Interferon-induced transmembrane proteins (IFITMs) block infection of many enveloped viruses, including the influenza A virus (IAV) that enters from late endosomes. IFITMs are thought to prevent virus hemifusion (merger of contacting leaflets without formation of a fusion pore) by altering the properties of cell membranes. Here we performed single IAV imaging and found that IFITM3 did not interfere with hemifusion, but prevented complete fusion. Also, contrary to a current view that excess cholesterol in late endosomes of IFITM3-expressing cells inhibits IAV entry, we show that cholesterol-laden endosomes are permissive for virus fusion. The ability of IFITM3 to block the formation of fusion pores implies that this protein stabilizes the cytoplasmic leaflet of endosomal membranes, either directly or indirectly, through altering its physical properties. IFITM3 may also redirect IAV to a non-productive pathway by promoting fusion with intralumenal vesicles of late endosomes instead of their limiting membrane.
- Published
- 2014
28. A novel DDB2-ATM feedback loop regulates human cytomegalovirus replication
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Xiaofei E, George Savidis, Christopher R. Chin, Shixia Wang, Shan Lu, Abraham L. Brass, and Timothy F. Kowalik
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Gene Expression Regulation, Viral ,DNA repair ,viruses ,Immunology ,Immunoblotting ,Cytomegalovirus ,Fluorescent Antibody Technique ,Eukaryotic DNA replication ,Ataxia Telangiectasia Mutated Proteins ,Biology ,Real-Time Polymerase Chain Reaction ,Transfection ,Virus Replication ,Microbiology ,DNA replication factor CDT1 ,Replication factor C ,Control of chromosome duplication ,Transduction, Genetic ,Virology ,Humans ,RNA, Small Interfering ,Genes, Immediate-Early ,Feedback, Physiological ,DNA replication ,Molecular biology ,Virus-Cell Interactions ,DNA-Binding Proteins ,Viral replication ,Insect Science ,Mutation ,biology.protein ,RNA Interference ,Nucleotide excision repair - Abstract
Human cytomegalovirus (HCMV) genome replication requires host DNA damage responses (DDRs) and raises the possibility that DNA repair pathways may influence viral replication. We report here that a nucleotide excision repair (NER)-associated-factor is required for efficient HCMV DNA replication. Mutations in genes encoding NER factors are associated with xeroderma pigmentosum (XP). One of the XP complementation groups, XPE, involves mutation in ddb2 , which encodes DNA damage binding protein 2 (DDB2). Infectious progeny virus production was reduced by >2 logs in XPE fibroblasts compared to levels in normal fibroblasts. The levels of immediate early (IE) (IE2), early (E) (pp65), and early/late (E/L) (gB55) proteins were decreased in XPE cells. These replication defects were rescued by infection with a retrovirus expressing DDB2 cDNA. Similar patterns of reduced viral gene expression and progeny virus production were also observed in normal fibroblasts that were depleted for DDB2 by RNA interference (RNAi). Mature replication compartments (RCs) were nearly absent in XPE cells, and there were 1.5- to 2.0-log reductions in viral DNA loads in infected XPE cells relative to those in normal fibroblasts. The expression of viral genes ( UL122 , UL44 , UL54 , UL55 , and UL84 ) affected by DDB2 status was also sensitive to a viral DNA replication inhibitor, phosphonoacetic acid (PAA), suggesting that DDB2 affects gene expression upstream of or events associated with the initiation of DNA replication. Finally, a novel, infection-associated feedback loop between DDB2 and ataxia telangiectasia mutated (ATM) was observed in infected cells. Together, these results demonstrate that DDB2 and a DDB2-ATM feedback loop influence HCMV replication.
- Published
- 2013
29. Amphotericin B increases influenza A virus infection by preventing IFITM3-mediated restriction
- Author
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Aaron R. Everitt, Sinu P. John, Stephen J. Elledge, David Sarlah, Simon Clare, Abraham L. Brass, Christopher R. Chin, Erick M. Carreira, George Savidis, Aaron M. Aker, Paul Kellam, Tsai-Yu Lin, and Jill M. Perreira
- Subjects
Nystatin ,Antifungal Agents ,medicine.disease_cause ,Virus Replication ,0601 Biochemistry and Cell Biology ,Neutralization ,Cell Fusion ,Mice ,FUSION ,Influenza A Virus, H1N1 Subtype ,Interferon ,Amphotericin B ,Chlorocebus aethiops ,Influenza A virus ,RNA, Small Interfering ,lcsh:QH301-705.5 ,Mice, Knockout ,0303 health sciences ,POLYENE MACROLIDE ANTIBIOTICS ,MEMBRANE-PROTEINS ,DERIVATIVES ,Tetraethylammonium ,3. Good health ,CELL-MEMBRANE ,Anti-Bacterial Agents ,COS Cells ,RNA Interference ,SEMLIKI FOREST ,Life Sciences & Biomedicine ,medicine.drug ,ENDOPLASMIC-RETICULUM ,Biology ,General Biochemistry, Genetics and Molecular Biology ,Microbiology ,Cell Line ,Cercopithecus aethiops ,03 medical and health sciences ,Immunocompromised Host ,Antigen ,Orthomyxoviridae Infections ,Report ,Influenza, Human ,medicine ,Animals ,Humans ,DENGUE VIRUS ,030304 developmental biology ,Science & Technology ,030306 microbiology ,Cell Membrane ,Sodium ,Membrane Proteins ,Biological Transport ,Cell Biology ,Virus Internalization ,Virology ,Antigens, Differentiation ,Acetylcholine ,WEST NILE VIRUS ,Mice, Inbred C57BL ,Viral replication ,lcsh:Biology (General) ,Cell culture ,Hela Cells ,1116 Medical Physiology ,Interferons ,IFITM PROTEINS - Abstract
Summary The IFITMs inhibit influenza A virus (IAV) replication in vitro and in vivo. Here, we establish that the antimycotic heptaen, amphotericin B (AmphoB), prevents IFITM3-mediated restriction of IAV, thereby increasing viral replication. Consistent with its neutralization of IFITM3, a clinical preparation of AmphoB, AmBisome, reduces the majority of interferon’s protective effect against IAV in vitro. Mechanistic studies reveal that IFITM1 decreases host-membrane fluidity, suggesting both a possible mechanism for IFITM-mediated restriction and its negation by AmphoB. Notably, we reveal that mice treated with AmBisome succumbed to a normally mild IAV infection, similar to animals deficient in Ifitm3. Therefore, patients receiving antifungal therapy with clinical preparations of AmphoB may be functionally immunocompromised and thus more vulnerable to influenza, as well as other IFITM3-restricted viral infections., Graphical Abstract, Highlights • Amphotericin B or AmBisome prevents IFITM3-mediated restriction of IAV • AmBisome overcomes the majority of IFN’s antiviral effects in vitro • IFITM1 decreases membrane fluidity and inhibits membrane fusion • AmBisome increases the morbidity and mortality of influenza, IFITM3 is a ubiquitously expressed antiviral protein that inhibits multiple human pathogenic viruses, including influenza A virus (IAV). Brass and colleagues now show that a widely used antifungal therapy, AmBisome, prevents IFITM3 from blocking IAV replication and that mice given AmBisome succumb to a normally mild influenza virus infection. Therefore, patients receiving antifungal therapy with AmBisome may be functionally immunocompromised and thus more vulnerable to influenza as well as other IFITM3-restricted viral infections.
- Published
- 2013
30. Expression and auto‐processing of hedgehog‐like proteins from Brugia malayi and Cryptosporidium
- Author
-
Kenneth V. Mills, George Savidis, Julie N. Reitter, Matthew J. Drago, and Sarah A. Cahn
- Subjects
biology ,Genetics ,Cryptosporidium ,biology.organism_classification ,Molecular Biology ,Biochemistry ,Hedgehog ,Molecular biology ,Brugia malayi ,Biotechnology - Published
- 2013
31. Expression and auto‐processing of hedgehog‐like proteins from Brugia malayi
- Author
-
George Savidis, Kenneth V. Mills, Julie N. Reitter, and Matthew J. Drago
- Subjects
biology ,Genetics ,biology.organism_classification ,Molecular Biology ,Biochemistry ,Hedgehog ,Brugia malayi ,Biotechnology ,Cell biology - Published
- 2012
32. Non‐canonical inteins: Protein splicing by alternate mechanisms
- Author
-
Kathryn M. Colelli, George Savidis, Julie N. Reitter, Michelle D. Marieni, Michael C. Nicastri, Jennie E. Williams, Laura M. Urbanski, Katherine R. Connor, and Kenneth V. Mills
- Subjects
Non canonical ,Chemistry ,Protein splicing ,Genetics ,Computational biology ,Molecular Biology ,Biochemistry ,Biotechnology - Published
- 2012
33. C. P. Cavafy : Collected Poems - Bilingual Edition
- Author
-
C. P. Cavafy, George Savidis, C. P. Cavafy, and George Savidis
- Abstract
C. P. Cavafy (1863-1933) lived in relative obscurity in Alexandria, and a collected edition of his poems was not published until after his death. Now, however, he is regarded as the most important figure in twentieth-century Greek poetry, and his poems are considered among the most powerful in modern European literature.This revised bilingual edition of Collected Poems offers the reader the original Greek texts facing what are now recognized as the standard English translations of Cavafy's poetry. It is this translation that best captures the poet's mixture of formal and idiomatic language and that preserves the immediacy of his increasingly frank treatment of homosexual eroticism, his brilliant re-creation of history, and his astute political ironies. This new bilingual edition also features the notes of editor George Savidis and a new foreword by Robert Pinsky.
- Published
- 2010
34. Direct Visualization of HIV-1 Replication Intermediates Shows that Capsid and CPSF6 Modulate HIV-1 Intra-nuclear Invasion and Integration
- Author
-
Christopher R. Chin, Jocelyn M. Portmann, Jill M. Perreira, Miles Smith, Eric M. Feeley, George Savidis, Abraham L. Brass, and Aaron M. Aker
- Subjects
DNA Replication ,Polyadenylation ,Virus Integration ,HIV Infections ,Genome, Viral ,Biology ,Virus Replication ,General Biochemistry, Genetics and Molecular Biology ,Article ,Capsid ,Cytosol ,Viral life cycle ,Cell Line, Tumor ,medicine ,Humans ,lcsh:QH301-705.5 ,Cell Nucleus ,mRNA Cleavage and Polyadenylation Factors ,DNA replication ,Reverse Transcription ,Molecular biology ,Reverse transcriptase ,3. Good health ,Cell biology ,Cell nucleus ,medicine.anatomical_structure ,lcsh:Biology (General) ,Viral replication ,HIV-1 ,Capsid Proteins ,HeLa Cells - Abstract
SummaryDirect visualization of HIV-1 replication would improve our understanding of the viral life cycle. We adapted established technology and reagents to develop an imaging approach, ViewHIV, which allows evaluation of early HIV-1 replication intermediates, from reverse transcription to integration. These methods permit the simultaneous evaluation of both the capsid protein (CA) and viral DNA genome (vDNA) components of HIV-1 in both the cytosol and nuclei of single cells. ViewHIV is relatively rapid, uses readily available reagents in combination with standard confocal microscopy, and can be done with virtually any HIV-1 strain and permissive cell lines or primary cells. Using ViewHIV, we find that CA enters the nucleus and associates with vDNA in both transformed and primary cells. We also find that CA’s interaction with the host polyadenylation factor, CPSF6, enhances nuclear entry and potentiates HIV-1’s depth of nuclear invasion, potentially aiding the virus’s integration into gene-dense regions.
- Full Text
- View/download PDF
35. RNASEK Is a V-ATPase-Associated Factor Required for Endocytosis and the Replication of Rhinovirus, Influenza A Virus, and Dengue Virus
- Author
-
George Savidis, Paul Meraner, Michael Franti, Annick Gauthier, William M. McDougall, Miles Smith, Jocelyn M. Portmann, Aaron M. Aker, Richard Baker, Jill M. Perreira, Motiur Rahman, Abraham L. Brass, and Christopher R. Chin
- Subjects
Vacuolar Proton-Translocating ATPases ,Rhinovirus ,Endosome ,Endocytic cycle ,Dengue virus ,Biology ,Virus Replication ,medicine.disease_cause ,Endocytosis ,General Biochemistry, Genetics and Molecular Biology ,Endoribonucleases ,medicine ,Influenza A virus ,Humans ,lcsh:QH301-705.5 ,ATP6AP1 ,Dengue Virus ,Virology ,Transmembrane protein ,3. Good health ,Cell biology ,lcsh:Biology (General) ,HeLa Cells - Abstract
SummaryHuman rhinovirus (HRV) causes upper respiratory infections and asthma exacerbations. We screened multiple orthologous RNAi reagents and identified host proteins that modulate HRV replication. Here, we show that RNASEK, a transmembrane protein, was needed for the replication of HRV, influenza A virus, and dengue virus. RNASEK localizes to the cell surface and endosomal pathway and closely associates with the vacuolar ATPase (V-ATPase) proton pump. RNASEK is required for endocytosis, and its depletion produces enlarged clathrin-coated pits (CCPs) at the cell surface. These enlarged CCPs contain endocytic cargo and are bound by the scissioning GTPase, DNM2. Loss of RNASEK alters the localization of multiple V-ATPase subunits and lowers the levels of the ATP6AP1 subunit. Together, our results show that RNASEK closely associates with the V-ATPase and is required for its function; its loss prevents the early events of endocytosis and the replication of multiple pathogenic viruses.
- Full Text
- View/download PDF
36. The Body of Man
- Author
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Vernon Young, Nguyen Ngoc Bich, Burton Raffel, W. S. Merwin, J. P. McCulloch, Sextus Propertius, Edmund Keeley, Philip Sherard, George Savidis, Odysseus Elytis, Kimon Friar, Nikos Stangos, Cesar Vallejo, Clayton Eshleman, Jose Rubia Barcia, David McDuff, Robert Bly, Josephine Miles, Judith Hemschemeyer, Maura Stanton, Richard Hugo, David R. Slavitt, Richard Murphy, Ronald Bottrall, and Ted Walker
- Subjects
Cultural Studies ,Literature and Literary Theory ,Visual Arts and Performing Arts - Published
- 1975
37. Collected Poems
- Author
-
Kimon Friar, C. P. Cavafy, Edmund Keeley, Philip Sherrard, and George Savidis
- Subjects
Literature and Literary Theory - Published
- 1977
38. The Axion Esti
- Author
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Kimon Friar, Odysseus Elytis, Edmund Keeley, and George Savidis
- Subjects
General Medicine - Published
- 1975
39. Passions and Ancient Days
- Author
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John E. Rexine, Edmund Keeley, Constantine Cavafy, and George Savidis
- Subjects
Literature ,History ,business.industry ,Passions ,General Medicine ,business - Published
- 1972
40. Poetry Chronicle
- Author
-
Richmond Lattimore, Robert Fitzgerald, Howard Moss, Adrienne Rich, Galway Kinnell, John Montague, Alan Stephens, Frederick Buell, L. E. Sissman, Vladimir Nabokov, C. P. Cavafy, Edmund Keeley, George Savidis, Charles Boer, and Norman R. Shapiro
- Subjects
Cultural Studies ,Literature and Literary Theory ,Visual Arts and Performing Arts - Published
- 1971
41. The Viral Restriction Factor IFITM3 Promotes Hemifusion but Blocks Full Fusion of Influenza Virus
- Author
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Tanay M. Desai, Mariana Marin, Christopher R. Chin, George Savidis, Abraham L. Brass, and Gregory B. Melikyan
- Subjects
Endosome ,Cell ,Biophysics ,Biology ,Dengue virus ,medicine.disease_cause ,Virology ,Virus ,Transmembrane protein ,Cytosol ,medicine.anatomical_structure ,Viral entry ,medicine ,Fusion mechanism - Abstract
Interferon-induced transmembrane proteins (IFITMs) are up-regulated as part of a cell's defense against viral challenges. These small proteins inhibit entry of diverse viruses, such as influenza A (IAV), West Nile and dengue virus. The mechanism by which IFITMs block viral entry is not understood. Recent reports suggest that IFITMs inhibits viral hemifusion (merger of proximal leaflets of the viral and cellular membranes), presumably by disrupting cholesterol trafficking and causing aberrant cholesterol accumulation in late endosomes. Here we employed time-resolved single IAV imaging to identify fusion step(s) affected by IFITM3 protein ectopically expressed in lung epithelial cells. These experiments revealed that, contrary to previous reports, lipid mixing between IAV and endosomes was, in fact, promoted upon IFITM3 expression. In contrast, virus-cell fusion assays monitoring the release of the viral content showed marked inhibition of fusion pore formation by IFITM3. This effect was not due to excessive cholesterol accumulation in endosomes or to reduced endosome acidity in IFITM3-expressing cells. Furthermore, conditions that induced the accumulation of cholesterol in late endosomes/lysosomes did not restrict IAV fusion. To conclude, IFITM3 blocks IAV fusion by disfavoring the formation of fusion pores, and this phenomenon is independent of cholesterol levels. We propose that IFITM3 can block viral fusion at a post-hemifusion stage either directly, by inserting into and stabilizing the cytosolic leaflet of endosomal membranes, or indirectly, by altering the lipid composition and thus disfavoring the formation of fusion pores. This work was partially supported by the NIH R01 GM054787 (to GBM) and 1R01AI091786 (to ALB) grants.
- Full Text
- View/download PDF
42. C. P. Cavafy : Collected Poems, Revised Edition
- Author
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C. P. Cavafy, George Savidis, C. P. Cavafy, and George Savidis
- Subjects
- Greek poetry--20th century, Greek poetry--19th century
- Abstract
C. P. Cavafy (1863–1933) lived in relative obscurity in Alexandria, and a collected edition of his poems was not published until after his death. Now, however, he is regarded as the most important figure in twentieth-century Greek poetry, and his poems are considered among the most powerful in modern European literature. Here is an extensively revised edition of the acclaimed translations of Edmund Keeley and Philip Sherrard, which capture Cavafy's mixture of formal and idiomatic use of language and preserve the immediacy of his frank treatment of homosexual themes, his brilliant re-creation of history, and his astute political ironies. The resetting of the entire edition has permitted the translators to review each poem and to make alterations where appropriate. George Savidis has revised the notes according to his latest edition of the Greek text.
- Published
- 1992
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