27 results on '"Abdul Ghafoor Khan"'
Search Results
2. Conformational Flexibility in the Immunoglobulin-Like Domain of the Hepatitis C Virus Glycoprotein E2
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Ieva Vasiliauskaite, Ania Owsianka, Patrick England, Abdul Ghafoor Khan, Sarah Cole, Dorothea Bankwitz, Steven K. H. Foung, Thomas Pietschmann, Joseph Marcotrigiano, Felix A. Rey, Arvind H. Patel, and Thomas Krey
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CD81 binding site ,hepatitis C virus ,Ig-like domain ,conformational flexibility ,glycoprotein E2 ,monoclonal antibodies ,Microbiology ,QR1-502 - Abstract
ABSTRACT The hepatitis C virus (HCV) glycoprotein E2 is the major target of neutralizing antibodies and is therefore highly relevant for vaccine design. Its structure features a central immunoglobulin (Ig)-like β-sandwich that contributes to the binding site for the cellular receptor CD81. We show that a synthetic peptide corresponding to a β-strand of this Ig-like domain forms an α-helix in complex with the anti-E2 antibody DAO5, demonstrating an inside-out flip of hydrophobic residues and a secondary structure change in the composite CD81 binding site. A detailed interaction analysis of DAO5 and cross-competing neutralizing antibodies with soluble E2 revealed that the Ig-like domain is trapped by different antibodies in at least two distinct conformations. DAO5 specifically captures retrovirus particles bearing HCV glycoproteins (HCVpp) and infectious cell culture-derived HCV particles (HCVcc). Infection of cells by DAO5-captured HCVpp can be blocked by a cross-competing neutralizing antibody, indicating that a single virus particle simultaneously displays E2 molecules in more than one conformation on its surface. Such conformational plasticity of the HCV E2 receptor binding site has important implications for immunogen design. IMPORTANCE Recent advances in the treatment of hepatitis C virus (HCV) infection with direct-acting antiviral drugs have enabled the control of this major human pathogen. However, due to their high costs and limited accessibility in combination with the lack of awareness of the mostly asymptomatic infection, there is an unchanged urgent need for an effective vaccine. The viral glycoprotein E2 contains regions that are crucial for virus entry into the host cell, and antibodies that bind to these regions can neutralize infection. One of the major targets of neutralizing antibodies is the central immunoglobulin (Ig)-like domain within E2. We show here that this Ig-like domain is conformationally flexible at the surface of infectious HCV particles and pseudoparticles. Our study provides novel insights into the interactions of HCV E2 with the humoral immune system that should aid future vaccine development.
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- 2017
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3. Identification of a novel drug lead that inhibits HCV infection and cell-to-cell transmission by targeting the HCV E2 glycoprotein.
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Reem R Al Olaby, Laurence Cocquerel, Adam Zemla, Laure Saas, Jean Dubuisson, Jost Vielmetter, Joseph Marcotrigiano, Abdul Ghafoor Khan, Felipe Vences Catalan, Alexander L Perryman, Joel S Freundlich, Stefano Forli, Shoshana Levy, Rod Balhorn, and Hassan M Azzazy
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Medicine ,Science - Abstract
Hepatitis C Virus (HCV) infects 200 million individuals worldwide. Although several FDA approved drugs targeting the HCV serine protease and polymerase have shown promising results, there is a need for better drugs that are effective in treating a broader range of HCV genotypes and subtypes without being used in combination with interferon and/or ribavirin. Recently, two crystal structures of the core of the HCV E2 protein (E2c) have been determined, providing structural information that can now be used to target the E2 protein and develop drugs that disrupt the early stages of HCV infection by blocking E2's interaction with different host factors. Using the E2c structure as a template, we have created a structural model of the E2 protein core (residues 421-645) that contains the three amino acid segments that are not present in either structure. Computational docking of a diverse library of 1,715 small molecules to this model led to the identification of a set of 34 ligands predicted to bind near conserved amino acid residues involved in the HCV E2: CD81 interaction. Surface plasmon resonance detection was used to screen the ligand set for binding to recombinant E2 protein, and the best binders were subsequently tested to identify compounds that inhibit the infection of Huh-7 cells by HCV. One compound, 281816, blocked E2 binding to CD81 and inhibited HCV infection in a genotype-independent manner with IC50's ranging from 2.2 µM to 4.6 µM. 281816 blocked the early and late steps of cell-free HCV entry and also abrogated the cell-to-cell transmission of HCV. Collectively the results obtained with this new structural model of E2c suggest the development of small molecule inhibitors such as 281816 that target E2 and disrupt its interaction with CD81 may provide a new paradigm for HCV treatment.
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- 2014
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4. Protection of Human rights and establishment of peace In the light of Islamic judiciary system
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Mr Abdul Ghafoor Khan and Dr Wahid Bakhsh
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Judiciary, Human Rights, Peace. Huquq ul Allah Huquq–al-Ibad - Abstract
Islam has divided the obligatory duties into Huquq ul Allah and Huquq–al-Ibad and complying with them guaranteed the success in this world and the hereafter. Islam not only connects rights and responsibilities with others, but also determines their priorities. Those nations where imbalance is created in discharging duties and rights get caught up in mischief and trouble as an unavoidable consequence as if human beings play the main role in the construction and destruction of the society peace. Maintaining justice as a whole is a vital part of an Islamic state; Allah (SWT) has ordered to show justice even with enemies. Justice cannot be denied in any case. In Islam the implementation of justice is as much important as the wreaking of a father cannot be taken from his son. Other religions also give importance to justice. Before Islam people had forgotten these principles but with the advent of Islam, the discrimination between rich and poor, master and slave was removed because favoring one side would create hatred and encourage class discrimination and would ultimately result in the decline of any state. Therefore, to protect the society from all such evils, Islam has laid importance on following rules of justice. In this perspective, the article describes the importance of justice, equality, reconstruction of judiciary and judicial system in an Islamic state., http://ojs.uopisl.pk/index.php/peshawarislamicus/article/view/80
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- 2022
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5. Product Line Diversification and Its Impact on Firm Performance
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Zia ur Rehman, Asad Khan, Rafique Ahmed Khuhro, and Abdul Ghafoor Khan
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The objective of the study is to measure product diversification’s impact on insurance firm’s financial performance in Pakistan. Analysis are carried out to examine how ownership structure, capitalization, group membership, firm size, diversification across business lines, industry concentration affects firm’s financial performance. Data from 2009-2019 is collected to measure the impact of diversification (entropy) on the risk- adjusted returns. Findings of the study reveal that business line diversification has strong positive effect on firm performance (for both ROA and ROE) which means that diversified firms perform better than non-diversified firms. For managers these findings are useful as they propose the need for diversification, capitalization, increase in size and group affiliation to enhance firm profitability.
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- 2021
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6. 466 PREVALENCE AND IMPACT OF FRAILTY IN PATIENTS HOSPITALISED WITH COVID-19. THE SALFORD EXPERIENCE IN WAVES 1 AND 2
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Roxanna Short, Abdul Ghafoor Khan, R Upton, A Price, M Narro-Vidal, H Allafi, A. Vilches-Moraga, T Kneen, F R Espinoza, Ben Carter, and A Dafnis
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Aging ,medicine.medical_specialty ,Coronavirus disease 2019 (COVID-19) ,business.industry ,Hazard ratio ,General Medicine ,Disease severity ,Internal medicine ,Severity of illness ,Clinical endpoint ,Medicine ,Observational study ,In patient ,Geriatrics and Gerontology ,business ,Survival analysis - Abstract
Introduction The COVID-19 pandemic has had an extensive impact on the frail older population, with significant rates of COVID-related hospital admissions and deaths amongst this vulnerable group. There is little evidence comparing the prevalence and impact of frailty amongst patients hospitalised with COVID-19 in wave 1 vs wave 2 of the pandemic. Methods Prospective observational study of all consecutive patients admitted to Salford Royal NHS Foundation Trust (SRFT) between 27th February and 28th of April 2020 (wave 1), and 1st October to 10th November 2020 (wave 2) with a diagnosis of COVID-19. The primary endpoint was in-hospital mortality. Patient demographics, co-morbidities, biochemical parameters, and frailty (using the Clinical Frailty Scale, score 1–4 = not frail, score 5–9 = frail) were collected. A Cox proportional hazards model associating wave and frailty with mortality was used. A logistic regression model was used to associate patient characteristics with wave. Both models adjusted for patient characteristics. Results A total of 700 patients were included (N = 429, wave 1; N = 271, wave 2). In wave 1, 42% (N = 180) were female; median age was 72; 37% (N = 160) were non-survivors, 49% (N = 212) were frail (CFS 5–9). In wave 2, 38% (N = 104) were female; median age was 73; 30% (N = 80) were non-survivors, 39% (N = 106) were frail. There was a reduction in mortality in wave 2, aHR = 0.71 (95% CI 0.53–0.94). Frailty was associated with increased mortality, after adjustment for age, wave and other patient characteristics. Patients were more frail in wave 1, and the effect of frailty was more pronounced in wave 1 vs wave 2. Conclusion Frailty is highly prevalent amongst patients of all ages admitted to SRFT with COVID-19. Higher scores of frailty are associated with increased mortality.
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- 2021
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7. Mitigation of T-cell dependent immunogenicity by reengineering factor VIIa analogue
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Gary Bembridge, Stepan S Surov, H.A. Daniel Lagassé, Mikhail V Ovanesov, Zuben E. Sauna, Wojciech Jankowski, Mark H. Fogg, Edward A. Cloake, Joseph Marcotrigiano, Joseph R. McGill, Campbell Bunce, Katarzyna I. Jankowska, and Abdul Ghafoor Khan
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0301 basic medicine ,T-Lymphocytes ,Population ,Factor VIIa ,030204 cardiovascular system & hematology ,Pharmacology ,Hemophilia A ,Protein Engineering ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Hemophilias ,Medicine ,Humans ,Immunogenetic Phenomena ,education ,Deimmunization ,Cells, Cultured ,Factor IX ,Blood coagulation test ,education.field_of_study ,Factor VII ,business.industry ,Immunogenicity ,Thrombin ,Hematology ,Turoctocog alfa ,Gene Therapy ,Recombinant Proteins ,030104 developmental biology ,chemistry ,Blood Coagulation Tests ,business ,medicine.drug - Abstract
Vatreptacog alfa (VA), a recombinant activated human factor VII (rFVIIa) variant with 3 amino acid substitutions, was developed to provide increased procoagulant activity in hemophilia patients with inhibitors to factor VIII or factor IX. In phase 3 clinical trials, changes introduced during the bioengineering of VA resulted in the development of undesired anti-drug antibodies in some patients, leading to the termination of a potentially promising therapeutic protein product. Here, we use preclinical biomarkers associated with clinical immunogenicity to validate our deimmunization strategy applied to this bioengineered rFVIIa analog. The reengineered rFVIIa analog variants retained increased intrinsic thrombin generation activity but did not elicit T-cell responses in peripheral blood mononuclear cells isolated from 50 HLA typed subjects representing the human population. Our algorithm, rational immunogenicity determination, offers a broadly applicable deimmunizing strategy for bioengineered proteins.
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- 2019
8. Functional and immunogenic characterization of diverse HCV glycoprotein E2 variants
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John Lok Man Law, Thomas Pietschmann, Joseph Marcotrigiano, Dorothea Bankwitz, Kai Schulze, Darren Hockman, Eike Steinmann, Richard J. C. Brown, Thomas Krey, Leona Dold, Alexander W. Tarr, Florian Klein, Michael P. Manns, Patrick Behrendt, Luisa J Ströh, Abdul Ghafoor Khan, Abel Viejo-Borbolla, Jason Wong, Mandy Doepke, Michael Houghton, Ulrich Spengler, Víctor González-Motos, Carlos A. Guzmán, Tanvi Khera, Daniel Todt, Michael Logan, Institut de Recherche sur les Maladies Virales et Hépatiques (IVH), Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM), TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany, and HZI, Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7 38124 Braunschweig, Germany.
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0301 basic medicine ,Glycosylation ,Immunogen ,viruses ,Hepacivirus ,Epitope ,Epitopes ,Mice ,chemistry.chemical_compound ,0302 clinical medicine ,Viral Envelope Proteins ,chemistry.chemical_classification ,Recombinant proteins ,Mice, Inbred BALB C ,biology ,Vaccination ,Hepatitis C ,HCV ,Hcv ,Receptors, Virus ,030211 gastroenterology & hepatology ,Antibody ,chemical and pharmacologic phenomena ,Cross Reactions ,Antibodies ,Tetraspanin 28 ,Viral Proteins ,03 medical and health sciences ,Antigen ,Cell Line, Tumor ,Animals ,Humans ,Binding site ,Glycoproteins ,Binding Sites ,Hepatology ,Viral Vaccines ,biochemical phenomena, metabolism, and nutrition ,Hepatitis C Antibodies ,Virology ,Hypervariable region ,HEK293 Cells ,030104 developmental biology ,chemistry ,biology.protein ,Glycoprotein ,Broadly Neutralizing Antibodies ,Gene Deletion ,[SDV.MHEP]Life Sciences [q-bio]/Human health and pathology - Abstract
Background & Aims Induction of cross-reactive antibodies targeting conserved epitopes of the envelope proteins E1E2 is a key requirement for an hepatitis C virus vaccine. Conserved epitopes like the viral CD81-binding site are targeted by rare broadly neutralizing antibodies. However, these viral segments are occluded by variable regions and glycans. We aimed to identify antigens exposing conserved epitopes and to characterize their immunogenicity. Methods We created hepatitis C virus variants with mutated glycosylation sites and/or hypervariable region 1 (HVR1). Exposure of the CD81 binding site and conserved epitopes was quantified by soluble CD81 and antibody interaction and neutralization assays. E2 or E1-E2 heterodimers with mutations causing epitope exposure were used to immunize mice. Vaccine-induced antibodies were examined and compared with patient-derived antibodies. Results Mutant viruses bound soluble CD81 and antibodies targeting the CD81 binding site with enhanced efficacy. Mice immunized with E2 or E1E2 heterodimers incorporating these modifications mounted strong, cross-binding, and non-interfering antibodies. E2-induced antibodies neutralized the autologous virus but they were not cross-neutralizing. Conclusions Viruses lacking the HVR1 and selected glycosylation sites expose the CD81 binding site and cross-neutralization antibody epitopes. Recombinant E2 proteins carrying these modifications induce strong cross-binding but not cross-neutralizing antibodies. Lay summary Conserved viral epitopes can be made considerably more accessible for binding of potently neutralizing antibodies by deletion of hypervariable region 1 and selected glycosylation sites. Recombinant E2 proteins carrying these mutations are unable to elicit cross-neutralizing antibodies suggesting that exposure of conserved epitopes is not sufficient to focus antibody responses on production of cross-neutralizing antibodies.
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- 2019
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9. Overcoming Challenges of Hepatitis C Virus Envelope Glycoprotein Production in Mammalian Cells
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Yuanyuan Wang, Samantha A. Yost, Abdul Ghafoor Khan, Jillian Whidby, and Joseph Marcotrigiano
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chemistry.chemical_classification ,0303 health sciences ,Glycan ,biology ,Chemistry ,Hepatitis C virus ,medicine.disease_cause ,biology.organism_classification ,Yeast ,Cell biology ,03 medical and health sciences ,Transduction (genetics) ,0302 clinical medicine ,Ectodomain ,Lentivirus ,medicine ,biology.protein ,Glycoprotein ,030217 neurology & neurosurgery ,Bacteria ,030304 developmental biology - Abstract
Posttranslational modifications (PTMs) are often required for proper folding and physiological function of proteins, including the envelope glycoproteins 1 and 2 (E1 and E2) of hepatitis C virus (HCV). Commonly used expression systems such as bacteria, yeast, and baculovirus produce soluble HCV E1 and E2 at very low yields, as the cellular environment and molecular machinery necessary for PTMs may be suboptimal or missing. Here, we describe an expression system for HCV E2 ectodomain (eE2) with 11 N-linked glycans and eight disulfide bonds, which combines lentivirus transduction of mammalian cells and a continuous growth, adherent cell bioreactor. It is environmentally friendly, as well as cost- and time-efficient compared to other methods of recombinant protein expression in mammalian systems with final yields of eE2 approaching 60 mg/L of cell culture supernatant. eE2 produced by this system is amenable to a variety of biophysical studies, including structural determination by X-ray crystallography. Considering the ease of use and flexibility, this method can be applied to express an array of difficult target proteins in a variety of mammalian cell lines.
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- 2018
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10. CD81 Receptor Regions outside the Large Extracellular Loop Determine Hepatitis C Virus Entry into Hepatoma Cells
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Lisa Lasswitz, Pia Banse, Thomas Pietschmann, Sina Kahl, Abdul Ghafoor Khan, Rebecca Moeller, Janina Bruening, Gisa Gerold, Joseph Marcotrigiano, and TWINCORE, Zentrum für experimentelle und klinischeInfektionsforschung GmbH, Feodor-Lynen-Str. 7, 30625 Hannover, Germany.
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hepatitis C virus ,0301 basic medicine ,HCV ,tetraspanin ,CD81 ,receptor ,chimeras ,susceptibility-determining domains ,transmembrane domain four ,cholesterol-binding residue ,lcsh:QR1-502 ,Infektionsmedicin ,Hepacivirus ,medicine.disease_cause ,lcsh:Microbiology ,Viral Envelope Proteins ,Tetraspanin ,Tumor Cells, Cultured ,Receptor ,Recombinant Proteins ,Cell biology ,Transmembrane domain ,Infectious Diseases ,embryonic structures ,Receptors, Virus ,Intracellular ,Protein Binding ,Infectious Medicine ,Hepatitis C virus ,Biology ,Article ,Cell Line ,Tetraspanin 28 ,03 medical and health sciences ,Chimera (genetics) ,Protein Domains ,Virology ,Extracellular ,medicine ,Animals ,Humans ,Amino Acid Sequence ,Sequence Homology, Amino Acid ,Virus Internalization ,digestive system diseases ,030104 developmental biology ,Mutation ,Hepatocytes - Abstract
Hepatitis C virus (HCV) enters human hepatocytes using four essential entry factors, one of which is human CD81 (hCD81). The tetraspanin hCD81 contains a large extracellular loop (LEL), which interacts with the E2 glycoprotein of HCV. The role of the non-LEL regions of hCD81 (intracellular tails, four transmembrane domains, small extracellular loop and intracellular loop) is poorly understood. Here, we studied the contribution of these domains to HCV susceptibility of hepatoma cells by generating chimeras of related tetraspanins with the hCD81 LEL. Our results show that non-LEL regions in addition to the LEL determine susceptibility of cells to HCV. While closely related tetraspanins (X. tropicalis CD81 and D. rerio CD81) functionally complement hCD81 non-LEL regions, distantly related tetraspanins (C. elegans TSP9 amd D. melanogaster TSP96F) do not and tetraspanins with intermediate homology (hCD9) show an intermediate phenotype. Tetraspanin homology and susceptibility to HCV correlate positively. For some chimeras, infectivity correlates with surface expression. In contrast, the hCD9 chimera is fully surface expressed, binds HCV E2 glycoprotein but is impaired in HCV receptor function. We demonstrate that a cholesterol-coordinating glutamate residue in CD81, which hCD9 lacks, promotes HCV infection. This work highlights the hCD81 non-LEL regions as additional HCV susceptibility-determining factors.
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- 2018
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11. The autoinhibitory CARD2-Hel2i Interface of RIG-I governs RNA selection
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Anand Ramanathan, Fuguo Jiang, Abdul Ghafoor Khan, Matthew T. Miller, Joseph Marcotrigiano, Swapnil C. Devarkar, and Smita S. Patel
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0301 basic medicine ,Molecular Sequence Data ,Fluorescence Polarization ,Biology ,DEAD-box RNA Helicases ,03 medical and health sciences ,Genetics ,Humans ,Receptors, Immunologic ,Small nucleolar RNA ,Binding site ,DEAD Box Protein 58 ,RNA, Double-Stranded ,Adenosine Triphosphatases ,Binding Sites ,Base Sequence ,RIG-I ,RNA ,Interferon-beta ,Non-coding RNA ,Molecular biology ,Long non-coding RNA ,Protein Structure, Tertiary ,Cell biology ,HEK293 Cells ,030104 developmental biology ,Signal transduction - Abstract
RIG-I (Retinoic Acid Inducible Gene-I) is a cytosolic innate immune receptor that detects atypical features in viral RNAs as foreign to initiate a Type I interferon signaling response. RIG-I is present in an autoinhibited state in the cytoplasm and activated by blunt-ended double-stranded (ds)RNAs carrying a 5′ triphosphate (ppp) moiety. These features found in many pathogenic RNAs are absent in cellular RNAs due to post-transcriptional modifications of RNA ends. Although RIG-I is structurally well characterized, the mechanistic basis for RIG-I's remarkable ability to discriminate between cellular and pathogenic RNAs is not completely understood. We show that RIG-I's selectivity for blunt-ended 5′-ppp dsRNAs is ≈3000 times higher than non-blunt ended dsRNAs commonly found in cellular RNAs. Discrimination occurs at multiple stages and signaling RNAs have high affinity and ATPase turnover rate and thus a high katpase/Kd. We show that RIG-I uses its autoinhibitory CARD2-Hel2i (second CARD-helicase insertion domain) interface as a barrier to select against non-blunt ended dsRNAs. Accordingly, deletion of CARDs or point mutations in the CARD2-Hel2i interface decreases the selectivity from ≈3000 to 150 and 750, respectively. We propose that the CARD2-Hel2i interface is a ‘gate’ that prevents cellular RNAs from generating productive complexes that can signal.
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- 2015
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12. Quantitative Proteomics Identifies Serum Response Factor Binding Protein 1 as a Host Factor for Hepatitis C Virus Entry
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Florian W. R. Vondran, Janina Bruening, Joseph Marcotrigiano, Felix Meissner, Thomas F. Baumert, Kathrin Welsch, Matthias Mann, Thomas Pietschmann, Gisa Gerold, Lars Kaderali, Abdul Ghafoor Khan, Paula Monteiro Perin, and Charles M. Rice
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Proteomics ,Receptor complex ,viruses ,Hepatitis C virus ,Quantitative proteomics ,Hepacivirus ,Sciences du Vivant [q-bio]/Médecine humaine et pathologie ,Biology ,medicine.disease_cause ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,Cell Line, Tumor ,medicine ,Humans ,lcsh:QH301-705.5 ,030304 developmental biology ,Host factor ,0303 health sciences ,Virus receptor ,030302 biochemistry & molecular biology ,virus diseases ,Virus Internalization ,biology.organism_classification ,Virology ,digestive system diseases ,3. Good health ,NS2-3 protease ,lcsh:Biology (General) ,Vesicular stomatitis virus ,Transcription Factors ,CD81 - Abstract
SummaryHepatitis C virus (HCV) enters human hepatocytes through a multistep mechanism involving, among other host proteins, the virus receptor CD81. How CD81 governs HCV entry is poorly characterized, and CD81 protein interactions after virus binding remain elusive. We have developed a quantitative proteomics protocol to identify HCV-triggered CD81 interactions and found 26 dynamic binding partners. At least six of these proteins promote HCV infection, as indicated by RNAi. We further characterized serum response factor binding protein 1 (SRFBP1), which is recruited to CD81 during HCV uptake and supports HCV infection in hepatoma cells and primary human hepatocytes. SRFBP1 facilitates host cell penetration by all seven HCV genotypes, but not of vesicular stomatitis virus and human coronavirus. Thus, SRFBP1 is an HCV-specific, pan-genotypic host entry factor. These results demonstrate the use of quantitative proteomics to elucidate pathogen entry and underscore the importance of host protein-protein interactions during HCV invasion.
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- 2015
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13. Conformational flexibility in the immunoglobulin-like domain of the Hepatitis C Virus Glycoprotein E2
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Dorothea Bankwitz, Steven K. H. Foung, Ieva Vasiliauskaite, Arvind H. Patel, Thomas Krey, Joseph Marcotrigiano, Sarah Cole, Patrick England, Félix A. Rey, Ania M. Owsianka, Thomas Pietschmann, Abdul Ghafoor Khan, TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany., Virologie Structurale - Structural Virology, Institut Pasteur [Paris] (IP)-Centre National de la Recherche Scientifique (CNRS), MRC - University of Glasgow Centre for Virus Research, Biophysique Moléculaire (Plate-forme), Rutgers University System (Rutgers), Centre for Experimental and Clinical Infection Research [Hanover] (TWINCORE), Department of Pathology [Stanford], Stanford Medicine, Stanford University-Stanford University, Centre for Experimental and Clinical Infection Research (TWINCORE), Helmholtz Centre for Infection Research (HZI)-Medizinische Hochschule Hannover (MHH), Hannover Medical School [Hannover] (MHH), German Center for Infection Research, Partnersite Munich (DZIF), This work was supported by an ANRS grant and recurrent funding from the Institut Pasteur to F.A.R., an ANRS grant to T.K., and funding to T.K. by the Deutsche Forschungsgemeinschaft within Project B10 of the Collaborative Research Centre SFB900 'Chronic Infections: Microbial Persistence and Its Control.' T.P. was supported by the Collaborative Research Centre SFB 900 project A6. Work in A.H.P.’s laboratory was supported by the Medical Research Council, United Kingdom (MC_UU12014/2)., and We thank Francois Bontems for critical reading of the manuscript, Ahmed Haouz and Patrick Weber from the crystallization platform for help in crystallization, and staff of the synchrotron beamline Proxima-1 at Synchrotron Soleil and PX-I at the Swiss Light Sources for help during data collection.
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0301 basic medicine ,conformational flexibility ,hepatitis C virus ,Immunogen ,Protein Conformation ,MESH: Virus Internalization ,[SDV]Life Sciences [q-bio] ,Hepacivirus ,medicine.disease_cause ,Antibodies, Viral ,Crystallography, X-Ray ,MESH: Antibodies, Monoclonal ,MESH: Antibodies, Neutralizing ,MESH: Tetraspanin 28 ,Epitopes ,MESH: Protein Conformation ,Viral Envelope Proteins ,MESH: Hepacivirus ,Neutralizing antibody ,Antibodies, Monoclonal ,Hepatitis C ,QR1-502 ,MESH: HEK293 Cells ,glycoprotein E2 ,vaccine design ,monoclonal antibodies ,Antibody ,Protein Binding ,Research Article ,Viral Hepatitis Vaccines ,MESH: Epitopes ,medicine.drug_class ,Viral protein ,Biology ,CD81 binding site ,Monoclonal antibody ,Microbiology ,Virus ,Tetraspanin 28 ,03 medical and health sciences ,Viral entry ,Virology ,medicine ,MESH: Protein Binding ,Humans ,MESH: Hepatitis C ,MESH: Immunoglobulin Domains ,MESH: Humans ,Binding Sites ,030102 biochemistry & molecular biology ,MESH: Viral Hepatitis Vaccines ,Virus Internalization ,MESH: Crystallography, X-Ray ,Antibodies, Neutralizing ,Ig-like domain ,NS2-3 protease ,030104 developmental biology ,HEK293 Cells ,MESH: Binding Sites ,MESH: Viral Envelope Proteins ,biology.protein ,Immunoglobulin Domains ,MESH: Antibodies, Viral - Abstract
The hepatitis C virus (HCV) glycoprotein E2 is the major target of neutralizing antibodies and is therefore highly relevant for vaccine design. Its structure features a central immunoglobulin (Ig)-like β-sandwich that contributes to the binding site for the cellular receptor CD81. We show that a synthetic peptide corresponding to a β-strand of this Ig-like domain forms an α-helix in complex with the anti-E2 antibody DAO5, demonstrating an inside-out flip of hydrophobic residues and a secondary structure change in the composite CD81 binding site. A detailed interaction analysis of DAO5 and cross-competing neutralizing antibodies with soluble E2 revealed that the Ig-like domain is trapped by different antibodies in at least two distinct conformations. DAO5 specifically captures retrovirus particles bearing HCV glycoproteins (HCVpp) and infectious cell culture-derived HCV particles (HCVcc). Infection of cells by DAO5-captured HCVpp can be blocked by a cross-competing neutralizing antibody, indicating that a single virus particle simultaneously displays E2 molecules in more than one conformation on its surface. Such conformational plasticity of the HCV E2 receptor binding site has important implications for immunogen design., IMPORTANCE Recent advances in the treatment of hepatitis C virus (HCV) infection with direct-acting antiviral drugs have enabled the control of this major human pathogen. However, due to their high costs and limited accessibility in combination with the lack of awareness of the mostly asymptomatic infection, there is an unchanged urgent need for an effective vaccine. The viral glycoprotein E2 contains regions that are crucial for virus entry into the host cell, and antibodies that bind to these regions can neutralize infection. One of the major targets of neutralizing antibodies is the central immunoglobulin (Ig)-like domain within E2. We show here that this Ig-like domain is conformationally flexible at the surface of infectious HCV particles and pseudoparticles. Our study provides novel insights into the interactions of HCV E2 with the humoral immune system that should aid future vaccine development.
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- 2017
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14. Entry of a heparan sulphate-binding HRV8 variant strictly depends on dynamin but not on clathrin, caveolin, and flotillin
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Leszek Gajdzik, Thomas C. Marlovits, Renate Fuchs, Angela Pickl-Herk, Abdul Ghafoor Khan, and Dieter Blaas
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Rhinovirus ,ICAM-1 ,Heparan sulphate ,Endocytosis ,Caveolins ,Clathrin ,Cell Line ,Dynamin II ,03 medical and health sciences ,Cytopathogenic Effect, Viral ,Virology ,Caveolin ,medicine ,Humans ,Serial Passage ,030304 developmental biology ,Dynamin ,Macropinocytosis ,0303 health sciences ,biology ,Pinocytosis ,030302 biochemistry & molecular biology ,Membrane Proteins ,Colocalization ,Virus Internalization ,Intercellular Adhesion Molecule-1 ,Amiloride ,Cell biology ,Host-Pathogen Interactions ,biology.protein ,Entry inhibitors ,Endocytic pathway ,medicine.drug - Abstract
The major group human rhinovirus type 8 can enter cells via heparan sulphate. When internalized into ICAM-1 negative rhabdomyosarcoma (RD) cells, HRV8 accumulated in the cells but caused CPE only after 3days when used at high MOI. Adaptation by three blind passages alternating between RD and HeLa cells resulted in variant HRV8v with decreased stability at acidic pH allowing for productive infection in the absence of ICAM-1. HRV8v produced CPE at 10 times lower MOI within 1day. Confocal fluorescence microscopy colocalization and the use of pharmacological and dominant negative inhibitors revealed that viral uptake is clathrin, caveolin, and flotillin independent. However, it is blocked by dynasore, amiloride, and EIPA. Furthermore, HRV8v induced FITC-dextran uptake and colocalized with this fluid phase marker. Except for the complete inhibition by dynasore, the entry pathway of HRV8v via HS is similar to that of HRV14 in RD cells that overexpress ICAM-1.
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- 2011
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15. Impact of flexible scheduling on employee performance regarding stress and work-family conflict
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Raja Abdul Ghafoor Khan, Furqan Ahmad Khan, Dr. Muhammad Aslam Khan, and Mohsin Shakeel
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Work-family conflict, flexible scheduling, work-family balance, employee performance ,jel:M1 - Abstract
Stress, work-family conflicts and flexible scheduling are three of the most important elements in organizational studies. The focus of current study is to understand the effect of Stress,work family conflicts and flexible scheduling on employee’s performance and also to understand whether flexible scheduling helps in reducing stress and work-family conflicts or not. The back bone of this study is the secondary data comprised of comprehensive literature review. A survey has also been conducted to strengthen the idea comprising of a sample of 70 employees from different organizations. 53 of them responded and the respond rate was 75%. Descriptive statistics is used to analyze the data. Results show that stress and work family conflict negatively affect the employee performance and flexible scheduling has a positive effect on employee performance. Primary study as well as literature review showed that flexible scheduling also helps in reducing stress and work-family conflicts. However, results are strongly based on the literature review i.e. secondary data.
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- 2011
16. Structural basis for m7G recognition and 2'-O-methyl discrimination in capped RNAs by the innate immune receptor RIG-I
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Anand Ramanathan, Smita S. Patel, Chen Wang, Matthew T. Miller, Swapnil C. Devarkar, Joseph Marcotrigiano, Fuguo Jiang, and Abdul Ghafoor Khan
- Subjects
0301 basic medicine ,RNA Caps ,Cell signaling ,viruses ,Amino Acid Motifs ,Retinoic acid ,Guanosine ,chemical and pharmacologic phenomena ,Biology ,medicine.disease_cause ,Crystallography, X-Ray ,Methylation ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Adenosine Triphosphate ,medicine ,Humans ,Nucleotide ,RNA, Double-Stranded ,chemistry.chemical_classification ,Mutation ,Multidisciplinary ,Innate immune system ,RIG-I ,Hydrolysis ,RNA ,virus diseases ,biochemical phenomena, metabolism, and nutrition ,Biological Sciences ,Immunity, Innate ,Protein Structure, Tertiary ,030104 developmental biology ,HEK293 Cells ,chemistry ,Biochemistry ,030220 oncology & carcinogenesis ,Nucleic Acid Conformation ,Carrier Proteins ,RNA Helicases ,Signal Transduction - Abstract
RNAs with 5′-triphosphate (ppp) are detected in the cytoplasm principally by the innate immune receptor Retinoic Acid Inducible Gene-I (RIG-I), whose activation triggers a Type I IFN response. It is thought that self RNAs like mRNAs are not recognized by RIG-I because 5′ppp is capped by the addition of a 7-methyl guanosine (m7G) (Cap-0) and a 2′-O-methyl (2′-OMe) group to the 5′-end nucleotide ribose (Cap-1). Here we provide structural and mechanistic basis for exact roles of capping and 2′-O-methylation in evading RIG-I recognition. Surprisingly, Cap-0 and 5′ppp double-stranded (ds) RNAs bind to RIG-I with nearly identical Kd values and activate RIG-I’s ATPase and cellular signaling response to similar extents. On the other hand, Cap-0 and 5′ppp single-stranded RNAs did not bind RIG-I and are signaling inactive. Three crystal structures of RIG-I complexes with dsRNAs bearing 5′OH, 5′ppp, and Cap-0 show that RIG-I can accommodate the m7G cap in a cavity created through conformational changes in the helicase-motif IVa without perturbing the ppp interactions. In contrast, Cap-1 modifications abrogate RIG-I signaling through a mechanism involving the H830 residue, which we show is crucial for discriminating between Cap-0 and Cap-1 RNAs. Furthermore, m7G capping works synergistically with 2′-O-methylation to weaken RNA affinity by 200-fold and lower ATPase activity. Interestingly, a single H830A mutation restores both high-affinity binding and signaling activity with 2′-O-methylated dsRNAs. Our work provides new structural insights into the mechanisms of host and viral immune evasion from RIG-I, explaining the complexity of cap structures over evolution.
- Published
- 2016
17. MEASUREMENT OF REAL NATIONAL INCOME IN PAKISTAN
- Author
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Abdul Ghafoor Khan
- Subjects
Economics and Econometrics ,Economic growth ,Measures of national income and output ,Economics - Published
- 2006
- Full Text
- View/download PDF
18. HCV glycoprotein structures: what to expect from the unexpected
- Author
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Abdul Ghafoor Khan, Matthew T. Miller, and Joseph Marcotrigiano
- Subjects
chemistry.chemical_classification ,biology ,Hepatitis C virus ,Hepacivirus ,Virion ,medicine.disease_cause ,Pathogenicity ,biology.organism_classification ,Protein multimerization ,Virology ,Virus ,Article ,Protein Structure, Tertiary ,Immune system ,chemistry ,Viral Envelope Proteins ,Immunology ,medicine ,Cost of treatment ,Humans ,Protein Multimerization ,Glycoprotein - Abstract
Hepatitis C virus (HCV) is continuing to spread worldwide, adding three million new infections each year. Currently approved therapies are highly effective; however, access to them is limited due to the high cost of treatment. Therefore, a cost effective vaccine and alternative antivirals remain essential. HCV envelope glycoproteins, E1 and E2, heterodimerize on the virion surface and are the major determinant for virus pathogenicity and host immune response. Recent structural insights into amino-terminal domain of E1 and core of E2 have revealed unexpected folds not present in glycoproteins from related viruses. Here we discuss these structural findings with respect to their role in HCV entry and impact on potential vaccine design and new antivirals.
- Published
- 2015
19. Identification of a Novel Drug Lead That Inhibits HCV Infection and Cell-to-Cell Transmission by Targeting the HCV E2 Glycoprotein
- Author
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Shoshana Levy, Jost Vielmetter, Laure Saas, Hassan M.E. Azzazy, Laurence Cocquerel, Jean Dubuisson, Reem R. Al Olaby, Adam Zemla, Felipe Vences Catalan, Stefano Forli, Alexander L. Perryman, Joseph Marcotrigiano, Rod Balhorn, Joel S. Freundlich, and Abdul Ghafoor Khan
- Subjects
RNA viruses ,Models, Molecular ,Viral Diseases ,Gastroenterology and hepatology ,lcsh:Medicine ,Plasma protein binding ,Protein Structure Prediction ,Hepacivirus ,medicine.disease_cause ,Crystallography, X-Ray ,Ligands ,Biochemistry ,Hepatitis ,Viral Envelope Proteins ,Interferon ,Biochemical Simulations ,Macromolecular Structure Analysis ,Biomacromolecule-Ligand Interactions ,lcsh:Science ,Polymerase ,Multidisciplinary ,Hepatitis C virus ,virus diseases ,Medical microbiology ,Small molecule ,Hepatitis C ,Recombinant Proteins ,Infectious hepatitis ,Infectious Diseases ,Viruses ,Thermodynamics ,medicine.drug ,Research Article ,Computer Modeling ,Protein Binding ,Protein Structure ,Computer and Information Sciences ,Genotype ,Cell Survival ,Molecular Sequence Data ,Biology ,Microbiology ,Antiviral Agents ,Tetraspanin 28 ,Cell Line, Tumor ,medicine ,Humans ,Amino Acid Sequence ,Binding site ,Molecular Biology ,Liver diseases ,ssRNA viruses ,Medicine and health sciences ,Binding Sites ,Biology and life sciences ,Flaviviruses ,lcsh:R ,Viral pathogens ,Organisms ,Proteins ,Computational Biology ,Surface Plasmon Resonance ,Virus Internalization ,Virology ,Molecular biology ,Microbial pathogens ,Kinetics ,Docking (molecular) ,Structural Homology, Protein ,biology.protein ,Molecular Complexes ,lcsh:Q ,CD81 - Abstract
Hepatitis C Virus (HCV) infects 200 million individuals worldwide. Although several FDA approved drugs targeting the HCV serine protease and polymerase have shown promising results, there is a need for better drugs that are effective in treating a broader range of HCV genotypes and subtypes without being used in combination with interferon and/or ribavirin. Recently, two crystal structures of the core of the HCV E2 protein (E2c) have been determined, providing structural information that can now be used to target the E2 protein and develop drugs that disrupt the early stages of HCV infection by blocking E2’s interaction with different host factors. Using the E2c structure as a template, we have created a structural model of the E2 protein core (residues 421–645) that contains the three amino acid segments that are not present in either structure. Computational docking of a diverse library of 1,715 small molecules to this model led to the identification of a set of 34 ligands predicted to bind near conserved amino acid residues involved in the HCV E2: CD81 interaction. Surface plasmon resonance detection was used to screen the ligand set for binding to recombinant E2 protein, and the best binders were subsequently tested to identify compounds that inhibit the infection of Huh-7 cells by HCV. One compound, 281816, blocked E2 binding to CD81 and inhibited HCV infection in a genotype-independent manner with IC50’s ranging from 2.2 µM to 4.6 µM. 281816 blocked the early and late steps of cell-free HCV entry and also abrogated the cell-to-cell transmission of HCV. Collectively the results obtained with this new structural model of E2c suggest the development of small molecule inhibitors such as 281816 that target E2 and disrupt its interaction with CD81 may provide a new paradigm for HCV treatment.
- Published
- 2014
20. Structure of the core ectodomain of the hepatitis C virus envelope glycoprotein 2
- Author
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Aryan A. Price, Caitlin Bohannon, Jillian Whidby, Joshy Jacob, Abdul Ghafoor Khan, Joseph Marcotrigiano, Alicja M. Cygan, Hannah Scarborough, Arash Grakoui, Alexandra V. Zatorski, Samantha A. Yost, and Matthew T. Miller
- Subjects
Models, Molecular ,Viral Hepatitis Vaccines ,Protein Folding ,Surface Properties ,Hepatitis C virus ,Hepacivirus ,Biology ,medicine.disease_cause ,Crystallography, X-Ray ,Virus ,Article ,Immunoglobulin Fab Fragments ,Protein structure ,Viral envelope ,Viral Envelope Proteins ,Scattering, Small Angle ,medicine ,Disulfides ,Multidisciplinary ,Hydrogen-Ion Concentration ,Virus Internalization ,Virology ,Fusion protein ,3. Good health ,Protein Structure, Tertiary ,NS2-3 protease ,Ectodomain ,Immunoglobulin G ,Hydrophobic and Hydrophilic Interactions ,Viral Fusion Proteins ,CD81 - Abstract
The crystal structure of the core domain of the hepatitis C virus surface glycoprotein E2 has been solved; the structure shows that, contrary to expectation, E2 is unlikely to be the viral fusion protein. There is currently no vaccine against hepatitis C virus, so it is important to learn more about the processes by which the virus establishes infection. Joseph Marcotrigiano and colleagues solve the crystal structure of the core domain of the hepatitis C virus surface glycoprotein E2. The structure shows that, contrary to expectation, E2 is unlikely to be the viral fusion protein. This work helps to clarify the role of E2 and the mechanism of hepatitis C virus entry. Hepatitis C virus (HCV) is a significant public health concern with approximately 160 million people infected worldwide1. HCV infection often results in chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. No vaccine is available and current therapies are effective against some, but not all, genotypes. HCV is an enveloped virus with two surface glycoproteins (E1 and E2). E2 binds to the host cell through interactions with scavenger receptor class B type I (SR-BI) and CD81, and serves as a target for neutralizing antibodies2,3,4. Little is known about the molecular mechanism that mediates cell entry and membrane fusion, although E2 is predicted to be a class II viral fusion protein. Here we describe the structure of the E2 core domain in complex with an antigen-binding fragment (Fab) at 2.4 A resolution. The E2 core has a compact, globular domain structure, consisting mostly of β-strands and random coil with two small α-helices. The strands are arranged in two, perpendicular sheets (A and B), which are held together by an extensive hydrophobic core and disulphide bonds. Sheet A has an IgG-like fold that is commonly found in viral and cellular proteins, whereas sheet B represents a novel fold. Solution-based studies demonstrate that the full-length E2 ectodomain has a similar globular architecture and does not undergo significant conformational or oligomeric rearrangements on exposure to low pH. Thus, the IgG-like fold is the only feature that E2 shares with class II membrane fusion proteins. These results provide unprecedented insights into HCV entry and will assist in developing an HCV vaccine and new inhibitors.
- Published
- 2013
21. Human Rhinovirus 14 Enters Rhabdomyosarcoma Cells Expressing ICAM-1 by a Clathrin-, Caveolin-, and Flotillin-Independent Pathway ▿
- Author
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Thomas C. Marlovits, Angela Pickl-Herk, Abdul Ghafoor Khan, Leszek Gajdzik, Dieter Blaas, and Renate Fuchs
- Subjects
Cytochalasin D ,Rhinovirus ,Immunology ,Integrin ,Microbiology ,Clathrin ,Caveolins ,Amiloride ,chemistry.chemical_compound ,Viral entry ,Virology ,Caveolae ,Cell Line, Tumor ,Caveolin ,Humans ,Cytochalasin ,ICAM-1 ,Muscle Cells ,Microscopy, Confocal ,biology ,Membrane Proteins ,Virus Internalization ,Intercellular Adhesion Molecule-1 ,Cell biology ,Virus-Cell Interactions ,Microscopy, Electron ,chemistry ,Microscopy, Fluorescence ,Insect Science ,biology.protein ,Sodium Channel Blockers - Abstract
Intercellular adhesion molecule 1 (ICAM-1) mediates binding and entry of major group human rhinoviruses (HRVs). Whereas the entry pathway of minor group HRVs has been studied in detail and is comparatively well understood, the pathway taken by major group HRVs is largely unknown. Use of immunofluorescence microscopy, colocalization with specific endocytic markers, dominant negative mutants, and pharmacological inhibitors allowed us to demonstrate that the major group virus HRV14 enters rhabdomyosarcoma cells transfected to express human ICAM-1 in a clathrin-, caveolin-, and flotillin-independent manner. Electron microscopy revealed that many virions accumulated in long tubular structures, easily distinguishable from clathrin-coated pits and caveolae. Virus entry was strongly sensitive to the Na+/H+ion exchange inhibitor amiloride and moderately sensitive to cytochalasin D. Thus, cellular uptake of HRV14 occurs via a pathway exhibiting some, but not all, characteristics of macropinocytosis and is similar to that recently described for adenovirus 3 entry via αvintegrin/CD46 in HeLa cells.
- Published
- 2010
22. Low pH-triggered beta-propeller switch of the low-density lipoprotein receptor assists rhinovirus infection
- Author
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Dieter Blaas, Abdul Ghafoor Khan, Gerhard Bilek, Leszek Gajdzig, Angela Pickl-Herk, Ursula Berka, Tuende Konecsni, and Renate Fuchs
- Subjects
Low-density lipoprotein receptor gene family ,Rhinovirus ,Endosome ,media_common.quotation_subject ,Immunology ,Mutant ,Virus Attachment ,CHO Cells ,Biology ,Microbiology ,Protein Structure, Secondary ,Cricetulus ,Virology ,Cricetinae ,Animals ,Humans ,cardiovascular diseases ,Internalization ,Receptor ,media_common ,Picornaviridae Infections ,Chinese hamster ovary cell ,food and beverages ,nutritional and metabolic diseases ,Transfection ,Hydrogen-Ion Concentration ,Virus Internalization ,Cell biology ,Virus-Cell Interactions ,Lipoproteins, LDL ,Biochemistry ,Receptors, LDL ,Insect Science ,LDL receptor ,Mutation ,RNA, Viral ,lipids (amino acids, peptides, and proteins) ,Lysosomes ,HeLa Cells - Abstract
Minor group human rhinoviruses (HRVs) bind three members of the low-density lipoprotein receptor (LDLR) family: LDLR proper, very-LDLR (VLDLR) and LDLR-related protein (LRP). Whereas ICAM-1, the receptor of major group HRVs actively contributes to viral uncoating, LDLRs are rather considered passive vehicles for cargo delivery to the low-pH environment of endosomes. Since the Tyr-Trp-Thr-Asp β-propeller domain of LDLR has been shown to be involved in the dissociation of bound LDL via intramolecular competition at low pH, we studied whether it also plays a role in HRV infection. Human cell lines deficient in LDLR family proteins are not available. Therefore, we used CHO -ldla7 cells that lack endogenous LDLR. These were stably transfected to express either wild-type (wt) human LDLR or a mutant with a deletion of the β-propeller. When HRV2 was attached to the propeller-negative LDLR, a lower pH was required for conversion to subviral particles than when attached to wt LDLR. This indicates that high-avidity receptor binding maintains the virus in its native conformation. HRV2 internalization directed the mutant LDLR but not wt LDLR to lysosomes, resulting in reduced plasma membrane expression of propeller-negative LDLR. Infection assays using a CHO-adapted HRV2 variant showed a delay in intracellular viral conversion and de novo viral synthesis in cells expressing the truncated LDLR. Our data indicate that the β-propeller attenuates the virus-stabilizing effect of LDLR binding and thereby facilitates RNA release from endosomes, resulting in the enhancement of infection. This is a nice example of a virus exploiting high-avidity multimodule receptor binding with an intrinsic release mechanism.
- Published
- 2009
23. Predictive bioinformatic identification of minor receptor group human rhinoviruses
- Author
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Angela Pickl-Herk, Sascha Strauss, Dieter Blaas, Christoph Weber, Abdul Ghafoor Khan, and Oliviero Carugo
- Subjects
Models, Molecular ,Rhinovirus ,Bioinformatics ,In silico ,Lysine ,Molecular Sequence Data ,Biophysics ,Virus Attachment ,Biology ,medicine.disease_cause ,Biochemistry ,Epitope ,03 medical and health sciences ,stomatognathic system ,Structural Biology ,Genetics ,medicine ,Humans ,Amino Acid Sequence ,Receptor ,Molecular Biology ,030304 developmental biology ,0303 health sciences ,030302 biochemistry & molecular biology ,virus diseases ,Computational Biology ,Cell Biology ,respiratory system ,Affinities ,LDL-receptor ,Energy calculation ,Capsid ,Affinity ,Receptors, LDL ,LDL receptor ,Capsid Proteins ,Molecular modelling ,Software ,Protein Binding - Abstract
Major group HRVs bind intercellular adhesion molecule 1 and minor group HRVs bind members of the low-density lipoprotein receptor (LDLR) family for cell entry. Whereas the former share common sequence motives in their viral capsid proteins (VPs), in the latter only a lysine residue within the binding epitope in VP1 is conserved; this lysine is also present in “K-type” major group HRVs that fail to use LDLR for infection. By using the available sequences three-dimensional models of VP1 of all HRVs were built and binding energies, with respect to module 3 of the very-low-density lipoprotein receptor, were calculated. Based on the predicted affinities K-type HRVs and minor group HRVs were correctly classified.
- Published
- 2009
24. Human Rhinovirus Type 2 Uncoating at the Plasma Membrane Is Not Affected by a pH Gradient but Is Affected by the Membrane Potential▿
- Author
-
Ursula Berka, Abdul Ghafoor Khan, Renate Fuchs, and Dieter Blaas
- Subjects
Rhinovirus ,Endosome ,Immunology ,Endosome lumen ,Biology ,Endocytosis ,Microbiology ,RNA Transport ,Membrane Potentials ,Cell membrane ,Valinomycin ,chemistry.chemical_compound ,Virology ,medicine ,Humans ,Membrane potential ,Cell Membrane ,Proton-Motive Force ,Depolarization ,Membrane hyperpolarization ,Virus Internalization ,Virus-Cell Interactions ,medicine.anatomical_structure ,Biochemistry ,chemistry ,Insect Science ,Biophysics ,RNA, Viral ,HeLa Cells - Abstract
The minor receptor group human rhinovirus type 2 enters host cells by endocytosis via members of the low-density-lipoprotein receptor family. In late endosomes, it undergoes a conformational change solely induced by a pH of ≤5.6, resulting in RNA transfer across the endosomal membrane into the cytoplasm. To determine potential driving forces of this process, we investigated whether RNA penetration might depend on the pH gradient and/or the membrane potential between the acidic endosome lumen and the neutral cytoplasm. Since these parameters are difficult to assess in endosomes, we took advantage of the possibility of inducing structural changes, RNA release, and consequently infection from the plasma membrane. To manipulate the pH gradient, cell-bound virus was exposed to membrane-permeant or -impermeant acidic buffers at 4°C, and this was followed by a shift to 34°C in medium containing bafilomycin to prevent RNA release from endosomes. To manipulate the plasma membrane potential, similar experiments were carried out, but these included K + diffusion potentials in the presence of the K + ionophore valinomycin. We demonstrated that infection does not depend on a pH gradient but is enhanced by plasma membrane hyperpolarization compared to plasma membrane depolarization.
- Published
- 2009
25. Human Rhinovirus Type 54 Infection via Heparan Sulfate Is Less Efficient and Strictly Dependent on Low Endosomal pH▿
- Author
-
Johannes Pichler, Abdul Ghafoor Khan, Anke Rosemann, and Dieter Blaas
- Subjects
Rhinovirus ,Immunology ,Virus Attachment ,CHO Cells ,Biology ,Virus Replication ,Microbiology ,Virus ,chemistry.chemical_compound ,Sulfation ,Cricetulus ,Virology ,Cell Line, Tumor ,Cricetinae ,Animals ,Humans ,Receptor ,Picornaviridae Infections ,Chinese hamster ovary cell ,Bafilomycin ,Heparan sulfate ,Hydrogen-Ion Concentration ,Intercellular Adhesion Molecule-1 ,Molecular biology ,Virus-Cell Interactions ,chemistry ,Biochemistry ,Proteoglycan ,Cell culture ,Insect Science ,biology.protein ,Macrolides ,Heparan Sulfate Proteoglycans - Abstract
K-type major-group human rhinoviruses (HRVs) (including HRV54) share a prominent lysine residue in the HI surface loop of VP1 with all minor-group HRVs. Despite the presence of this residue, they cannot use members of the low-density lipoprotein receptor family for productive infection. Reexamining all K-type viruses for receptor usage, we noticed that HRV54 is able to replicate in RD cells that lack the major-group receptor intercellular adhesion molecule 1 (ICAM-1). By using receptor blocking assays, inhibition of sulfation, enzymatic digestion, and proteoglycan-deficient cell lines, we show here that wild-type HRV54, without any adaptation, uses heparan sulfate (HS) proteoglycan as an alternate receptor. However, infection via HS is less efficient than infection via ICAM-1. Moreover, HRV54 has an acid lability profile similar to that of the minor-group virus HRV2. In ICAM-1-deficient cells its replication is completely blocked by the H + -ATPase inhibitor bafilomycin A1, whereas in ICAM-1-expressing cells it replicates in the presence of the drug. Thus, use of a “noncatalytic” receptor requires the virus to be highly unstable at low pH.
- Published
- 2007
26. P1223 E2216 … A PROMISING DRUG LEAD THAT INHIBITS HCV INFECTIVITY THROUGH TARGETING HCV E2
- Author
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Jost Vielmetter, R.R. Al Olaby, Stefano Forli, Hassan M.E. Azzazy, Laure Saas, Adam Zemla, Jean Dubuisson, Abdul Ghafoor Khan, Rod Balhorn, Laurence Cocquerel, Joseph Marcotrigiano, and J. Whidby
- Subjects
Infectivity ,African american ,Drug ,medicine.medical_specialty ,Hepatology ,business.industry ,Samatasvir ,media_common.quotation_subject ,Ribavirin ,Gastroenterology ,Virology ,chemistry.chemical_compound ,chemistry ,Internal medicine ,medicine ,business ,Lead (electronics) ,media_common - Abstract
Methods: This is a randomized, double-blind, parallel-group study in treatment-naive subjects with GT1b and 4 chronic HCV infection. Subjects received 50, 100, or 150 mg samatasvir + SMV 150mg + weight-based ribavirin (RBV) daily for 12 weeks. Results: 63 subjects randomized: 59% female, 24% African American, 91% GT1b and 8% GT4 HCV infection. Mean baseline HCVRNA was 6.4 log10 IU/mL. On-treatment responses are presented in the table.
- Published
- 2014
- Full Text
- View/download PDF
27. The relationship of capital structure decisions with firm performance: A study of the engineering sector of Pakistan
- Author
-
Abdul Ghafoor Khan
- Subjects
Finance ,Return on assets ,Capital structure ,business.industry ,media_common.quotation_subject ,Monetary economics ,Return on equity ,Negative relationship ,Stock exchange ,Debt ,Economics ,Debt ratio ,Asset (economics) ,business ,media_common - Abstract
Purpose: The purpose of this study is to find the relationship of capital structure decision with the performance of the firms in the developing market economies like Pakistan.Methodology: Pooled Ordinary Least Square regression was applied to 36 engineering sector firms in Pakistani market listed on the Karachi Stock Exchange (KSE) during the period 2003-2009.Findings: The results show that financial leverage measured by short term debt to total assets (STDTA) and total debt to total assets (TDTA) has a significantly negative relationship with the firm performance measured by Return on Assets (ROA), Gross Profit Margin (GM) and Tobin’s Q. The relationship between financial leverage and firm performance measured by the return on equity (ROE) is negative but insignificant. Asset size has an insignificant relationship with the firm performance measured by ROA and GM but negative and significant relationship exists with Tobin’s Q. Firms in the engineering sector of Pakistan are largely dependent on short term debt but debts are attached with strong covenants which affect the performance of the firm.Originality/Value: This is first paper to study an individual sector like engineering industry in Pakistan on the mentioned topic.
- Published
- 2012
- Full Text
- View/download PDF
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