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Sundaram B, Pandian N, Mall R, Wang Y, Sarkar R, Kim HJ, Malireddi RKS, Karki R, Janke LJ, Vogel P, Kanneganti TD. NLRP12-PANoptosome activates PANoptosis and pathology in response to heme and PAMPs. Cell 2023; 186:2783-2801.e20. [PMID: 37267949 PMCID: PMC10330523 DOI: 10.1016/j.cell.2023.05.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 54.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 03/17/2023] [Accepted: 05/05/2023] [Indexed: 06/04/2023]
Abstract
Cytosolic innate immune sensors are critical for host defense and form complexes, such as inflammasomes and PANoptosomes, that induce inflammatory cell death. The sensor NLRP12 is associated with infectious and inflammatory diseases, but its activating triggers and roles in cell death and inflammation remain unclear. Here, we discovered that NLRP12 drives inflammasome and PANoptosome activation, cell death, and inflammation in response to heme plus PAMPs or TNF. TLR2/4-mediated signaling through IRF1 induced Nlrp12 expression, which led to inflammasome formation to induce maturation of IL-1β and IL-18. The inflammasome also served as an integral component of a larger NLRP12-PANoptosome that drove inflammatory cell death through caspase-8/RIPK3. Deletion of Nlrp12 protected mice from acute kidney injury and lethality in a hemolytic model. Overall, we identified NLRP12 as an essential cytosolic sensor for heme plus PAMPs-mediated PANoptosis, inflammation, and pathology, suggesting that NLRP12 and molecules in this pathway are potential drug targets for hemolytic and inflammatory diseases.
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Affiliation(s)
- Balamurugan Sundaram
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Nagakannan Pandian
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Raghvendra Mall
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Yaqiu Wang
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Roman Sarkar
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Hee Jin Kim
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | | | - Rajendra Karki
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Laura J Janke
- Animal Resources Center and the Veterinary Pathology Core, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Peter Vogel
- Animal Resources Center and the Veterinary Pathology Core, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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Rice A, Haldar S, Wang E, Blank PS, Akimov SA, Galimzyanov TR, Pastor RW, Zimmerberg J. Planar aggregation of the influenza viral fusion peptide alters membrane structure and hydration, promoting poration. Nat Commun 2022; 13:7336. [PMID: 36470871 PMCID: PMC9722698 DOI: 10.1038/s41467-022-34576-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 10/28/2022] [Indexed: 12/07/2022] Open
Abstract
To infect, enveloped viruses employ spike protein, spearheaded by its amphipathic fusion peptide (FP), that upon activation extends out from the viral surface to embed into the target cellular membrane. Here we report that synthesized influenza virus FPs are membrane active, generating pores in giant unilamellar vesicles (GUV), and thus potentially explain both influenza virus' hemolytic activity and the liposome poration seen in cryo-electron tomography. Experimentally, FPs are heterogeneously distributed on the GUV at the time of poration. Consistent with this heterogeneous distribution, molecular dynamics (MD) simulations of asymmetric bilayers with different numbers of FPs in one leaflet show FP aggregation. At the center of FP aggregates, a profound change in the membrane structure results in thinning, higher water permeability, and curvature. Ultimately, a hybrid bilayer nanodomain forms with one lipidic leaflet and one peptidic leaflet. Membrane elastic theory predicts a reduced barrier to water pore formation when even a dimer of FPs thins the membrane as above, and the FPs of that dimer tilt, to continue the leaflet bending initiated by the hydrophobic mismatch between the FP dimer and the surrounding lipid.
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Affiliation(s)
- Amy Rice
- grid.94365.3d0000 0001 2297 5165Laboratory of Computational Biology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD USA
| | - Sourav Haldar
- grid.94365.3d0000 0001 2297 5165Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD USA ,grid.418363.b0000 0004 0506 6543Present Address: Division of Virus Research and Therapeutics, CSIR-Central Drug Research Institute, Lucknow, UP India
| | - Eric Wang
- grid.94365.3d0000 0001 2297 5165Laboratory of Computational Biology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD USA ,grid.94365.3d0000 0001 2297 5165Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD USA
| | - Paul S. Blank
- grid.94365.3d0000 0001 2297 5165Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD USA
| | - Sergey A. Akimov
- grid.4886.20000 0001 2192 9124A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
| | - Timur R. Galimzyanov
- grid.4886.20000 0001 2192 9124A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia ,grid.35043.310000 0001 0010 3972National University of Science and Technology “MISiS”, 4 Leninskiy Prospect, Moscow, Russia
| | - Richard W. Pastor
- grid.94365.3d0000 0001 2297 5165Laboratory of Computational Biology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD USA
| | - Joshua Zimmerberg
- grid.94365.3d0000 0001 2297 5165Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD USA
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3
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Almeida CF, Purcell DFJ, Godfrey DI, McAuley JL. The Efficacy of Common Household Cleaning Agents for SARS-CoV-2 Infection Control. Viruses 2022; 14:v14040715. [PMID: 35458445 PMCID: PMC9026400 DOI: 10.3390/v14040715] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 03/13/2022] [Accepted: 03/24/2022] [Indexed: 02/04/2023] Open
Abstract
The COVID-19 pandemic caused by SARS-CoV-2 is having devastating effects on a global scale. Since common household disinfectants are often used to minimise the risk of infection in the home and work environment, we investigated the ability of some of these products to inactivate the virus. We tested generic brands of vinegar, bleach, and dishwashing detergent, as well as laboratory-grade acetic acid, sodium hypochlorite, and ethanol. Assays were conducted at room temperature (18–20 °C, 40% relative humidity), and two time points were used to reflect a quick wipe (30 s) and a brief soak (5 min). Vinegar, and its active ingredient, acetic acid, were completely ineffective at virus inactivation even when exposed to the virus at 90% v/v (a final concentration equivalent to 3.6% v/v acetic acid). In contrast, ethanol was capable of inactivating the virus at dilutions as low as 40% v/v. Dishwashing detergent effectively rendered SARS-CoV-2 inactive when diluted 100-fold (1% v/v). Bleach was found to be fully effective against SARS-CoV-2 at 0.21 g/L sodium hypochlorite after a 30 s exposure (1/200 dilution of commercial product). Given reports of infectious virus recovered from the surface of frozen packaging, we tested the persistence of infectiousness after multiple freeze-thaw cycles and found no change in infectious SARS-CoV-2 titre after seven freeze-thaw cycles. These results should help inform readers of how to effectively disinfect surfaces and objects that have potentially been contaminated with SARS-CoV-2 using common household chemicals.
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Affiliation(s)
- Catarina F. Almeida
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000, Australia; (C.F.A.); (D.F.J.P.); (D.I.G.)
| | - Damian F. J. Purcell
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000, Australia; (C.F.A.); (D.F.J.P.); (D.I.G.)
- Global Virus Network Center of Excellence at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000, Australia
| | - Dale I. Godfrey
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000, Australia; (C.F.A.); (D.F.J.P.); (D.I.G.)
| | - Julie L. McAuley
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000, Australia; (C.F.A.); (D.F.J.P.); (D.I.G.)
- Global Virus Network Center of Excellence at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000, Australia
- Correspondence:
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Bardi MJ, Oliaee MA. Impacts of different operational temperatures and organic loads in anaerobic co-digestion of food waste and sewage sludge on the fate of SARS-CoV-2. PROCESS SAFETY AND ENVIRONMENTAL PROTECTION : TRANSACTIONS OF THE INSTITUTION OF CHEMICAL ENGINEERS, PART B 2021; 146:464-472. [PMID: 33262558 PMCID: PMC7694560 DOI: 10.1016/j.psep.2020.11.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/16/2020] [Accepted: 11/21/2020] [Indexed: 05/05/2023]
Abstract
The impacts of different operational temperatures, and organic load (OL) on the fate of SARS-CoV-2 during the anaerobic co-digestion of food waste (FW) and sewage sludge (SS) was evaluated. The lab-scaled batch reactors (i.e. R1-R7) were performed under psychrophilic, mesophilic, and thermophilic conditions and the OL of systems was 1.5, 3.5, 6 gVS/L. The performance parameters showed that at higher OL the stability of systems failed and low biogas was produced. In contrast, increasing of operational temperature of systems induced more biogas generation due to the increment of metabolic activity of bacteria. Therefore, R1-R7 achieved biogas yield of 202.5, 249, 187, 260, 246, 163, and 300 mL/gVS respectively. Both SARS-CoV-2 genes i.e. ORF1ab, and N genes were detected in the effluent of psychrophilic reactors i.e. R1, and R2, with a total concentration of 46 × 103, and 11 × 103 copies/L respectively. In R3, no viral genes were observed, when the VFAs was accumulated up to 2000 mg/L and caused a pH drop to 5.6. At the mesophilic condition, the viral concentration was significantly declined, and no viral genes were observed at an OL of 3.5 gVS/L. Furthermore, the synergistic effect of temperature and accumulation of intermediate metabolites provided a sever condition for SARS-CoV-2 survival at an operational temperature and OL of 50 °C, and 1.5 gVS/L respectively.
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Affiliation(s)
- Mohammad Javad Bardi
- Faculty of Civil Engineering, Division of Environmental Engineering, Babol Noshirvani University of Technology, Babol, Iran
| | - Mohammad Amin Oliaee
- Faculty of Civil Engineering, Division of Environmental Engineering, Babol Noshirvani University of Technology, Babol, Iran
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5
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Sangkakam A, Hemachudha P, Saraya AW, Thaweethee-Sukjai B, Cheun-Arom T, Latinne A, Olival KJ, Wacharapluesadee S. Detection of influenza virus in rectal swabs of patients admitted in hospital for febrile illnesses in Thailand. SAGE Open Med 2021; 9:2050312121989631. [PMID: 33552519 PMCID: PMC7841862 DOI: 10.1177/2050312121989631] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 12/30/2020] [Indexed: 11/17/2022] Open
Abstract
Introduction Influenza virus favours the respiratory tract as its primary site of host entry and replication, and it is transmitted mainly via respiratory secretions. Nasopharyngeal swab is the gold standard specimen type for influenza detection, but several studies have also suggested that the virus replicates in the human gastrointestinal tract. Methods A retrospective study was conducted on all patients positive for influenza virus and initially recruited as part of the PREDICT project from 2017 to 2018. The objectives of the study were to investigate whether rectal swab could aid in improving influenza detection, and if there was any correlation between gastrointestinal disturbances and severity of infection, using length of hospital stay as an indicator of severity. Results Of the 51 influenza-positive patients, 12 had detectable influenza virus in their rectal swab. Among these 12 rectal swab positive patients, influenza virus was not detected in the nasopharyngeal swab of three of them. Gastrointestinal symptoms were observed for 28.2% patients with a negative rectal swab negative and 25.0% patients with a positive rectal swab. Average length of hospital stay was 4.2 days for rectal swab positive group and 3.7 days for rectal swab negative group. This difference was not statistically significant (p = 0.288). Conclusions There is no correlation between influenza virus detection in rectal swab and gastrointestinal disturbances or disease severity, and there is currently insufficient evidence to support replicative ability in the gastrointestinal tract.
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Affiliation(s)
- Artit Sangkakam
- Department of Internal Medicine, Loei Hospital, Loei, Thailand
| | - Pasin Hemachudha
- Thai Red Cross Emerging Infectious Diseases-Health Science Centre, World Health Organization Collaborating Centre for Research and Training on Viral Zoonoses, Chulalongkorn Hospital, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Abhinbhen W Saraya
- Thai Red Cross Emerging Infectious Diseases-Health Science Centre, World Health Organization Collaborating Centre for Research and Training on Viral Zoonoses, Chulalongkorn Hospital, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Benjamard Thaweethee-Sukjai
- Thai Red Cross Emerging Infectious Diseases-Health Science Centre, World Health Organization Collaborating Centre for Research and Training on Viral Zoonoses, Chulalongkorn Hospital, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Thaniwan Cheun-Arom
- Department of Biology, Faculty of Science, Ramkhamhaeng University, Bangkok, Thailand
| | - Alice Latinne
- EcoHealth Alliance, New York, NY, USA.,Wildlife Conservation Society, Viet Nam Country Program, Ha Noi, Viet Nam.,Wildlife Conservation Society, Health Program, Bronx, NY, USA
| | | | - Supaporn Wacharapluesadee
- Thai Red Cross Emerging Infectious Diseases-Health Science Centre, World Health Organization Collaborating Centre for Research and Training on Viral Zoonoses, Chulalongkorn Hospital, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
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6
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Natural and Experimental Persistence of Highly Pathogenic H5 Influenza Viruses in Slurry of Domestic Ducks, with or without Lime Treatment. Appl Environ Microbiol 2020; 86:AEM.02288-20. [PMID: 33008818 PMCID: PMC7688237 DOI: 10.1128/aem.02288-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 09/21/2020] [Indexed: 11/25/2022] Open
Abstract
From November 2015 to July 2017, two successive episodes of H5 highly pathogenic avian influenza viruses (HP AIVs) infections occurred on poultry farms in France, mostly in domestic ducks raised for foie gras production in southwestern France. During the two epizootics, epidemiological investigations were carried out on infected farms and control and biosafety measures were implemented in association with surveillance in order to stop the spread of the viruses. Effluents are known to be an important factor in environmental dissemination of viruses, and suitable effluent management is needed to help prevent the spread of epizootics to other farms or pathogen persistence at the farm level. The present study was therefore designed to assess how long infectious A/H5 HP AIVs can persist in naturally or experimentally contaminated fecal slurry samples from ducks, with or without sanitization by lime treatment. Infections by A/H5 and A/H7 avian influenza viruses (AIVs) can cause acute disease and are therefore notifiable in poultry and wild birds. During winter 2015-2016, several cases of infection caused by highly pathogenic (HP) AIVs belonging to the A/H5N1, A/H5N2, and A/H5N9 subtypes were detected in southwestern France. Throughout winter 2016-2017, several cases of infections caused mainly by A/H5N8 HP AIV (A/goose/GD/1/1996, clade 2.3.4.4) were detected across Europe. On both occasions, the viruses were widely detected on palmiped farms in France. This study was designed to evaluate the persistence of A/H5 HP AIV in slurry from various duck productions. This was achieved (i) in the laboratory setting by artificially spiking four AIV-free slurry samples with known amounts of A/H5N9 HP AIV and monitoring virus infectivity, with or without lime treatment to achieve pH 10 or pH 12, and (ii) by sampling slurry tanks on five naturally A/H5N8 HP-contaminated farms. Experimental results in artificially spiked slurry suggested virus survival for 4 weeks in slurry from Muscovy or Pekin duck breeders and for 2 weeks in slurry from ducks for foie gras production during the assisted-feeding period, without lime treatment. Persistence of infectious A/H5N9 HP AIV in all slurry samples after lime treatment at pH 10 or pH 12 was less than 1 week. The A/H5N8 HP AIV persisted in naturally contaminated untreated slurry for 7 weeks. The results obtained provide experimental support for the 60-day storage period without treatment or the 7-day interval after lime treatment defined in French regulations for slurry sanitization. IMPORTANCE From November 2015 to July 2017, two successive episodes of H5 highly pathogenic avian influenza viruses (HP AIVs) infections occurred on poultry farms in France, mostly in domestic ducks raised for foie gras production in southwestern France. During the two epizootics, epidemiological investigations were carried out on infected farms and control and biosafety measures were implemented in association with surveillance in order to stop the spread of the viruses. Effluents are known to be an important factor in environmental dissemination of viruses, and suitable effluent management is needed to help prevent the spread of epizootics to other farms or pathogen persistence at the farm level. The present study was therefore designed to assess how long infectious A/H5 HP AIVs can persist in naturally or experimentally contaminated fecal slurry samples from ducks, with or without sanitization by lime treatment.
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7
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Lim K, Kodera N, Wang H, Mohamed MS, Hazawa M, Kobayashi A, Yoshida T, Hanayama R, Yano S, Ando T, Wong RW. High-Speed AFM Reveals Molecular Dynamics of Human Influenza A Hemagglutinin and Its Interaction with Exosomes. NANO LETTERS 2020; 20:6320-6328. [PMID: 32787163 DOI: 10.1021/acs.nanolett.0c01755] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Influenza A hemagglutinin (HA) is one of the crucial virulence factors that mediate host tropism and viral infectivity. Presently, the mechanism of the fusogenic transition of HA remains elusive. Here, we used high-speed atomic force microscopy (HS-AFM) to decipher the molecular dynamics of HA and its interaction with exosomes. Our data reveal that the native conformation of HA in the neutral buffer is ellipsoidal, and HA undergoes a conformational change in an acidic buffer. Real-time visualization of the fusogenic transition by HS-AFM suggests that the mechanism is possibly fit to the "uncaging" model, and HA intermediate appears as Y-shaped. A firm interaction between the HA and exosome in an acidic buffer indicates the insertion of a fusion peptide into the exosomal layer and subsequently destabilizes the layer, resulting in the deformation or rupture of exosomes, releasing exosomal contents. In contrast, the HA-exosome interaction is weak in a neutral buffer because the interaction is mediated by weak bonds between the HA receptor-binding site and receptors on the exosome.
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Affiliation(s)
- Keesiang Lim
- WPI-Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Noriyuki Kodera
- WPI-Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Hanbo Wang
- Cell-Bionomics Research Unit, Institute for Frontier Science Initiative (INFINITI), Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Mahmoud Shaaban Mohamed
- Cell-Bionomics Research Unit, Institute for Frontier Science Initiative (INFINITI), Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Masaharu Hazawa
- WPI-Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- Cell-Bionomics Research Unit, Institute for Frontier Science Initiative (INFINITI), Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Akiko Kobayashi
- Cell-Bionomics Research Unit, Institute for Frontier Science Initiative (INFINITI), Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Takeshi Yoshida
- WPI-Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- Department of Immunology, Kanazawa University Graduate School of Medical Sciences, 13-1 Takara, Kanazawa, Ishikawa 920-8640, Japan
| | - Rikinari Hanayama
- WPI-Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- Department of Immunology, Kanazawa University Graduate School of Medical Sciences, 13-1 Takara, Kanazawa, Ishikawa 920-8640, Japan
| | - Seiji Yano
- WPI-Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- Division of Medical Oncology, Cancer Research Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Toshio Ando
- WPI-Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Richard W Wong
- WPI-Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- Cell-Bionomics Research Unit, Institute for Frontier Science Initiative (INFINITI), Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
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Minodier L, Charrel RN, Ceccaldi PE, van der Werf S, Blanchon T, Hanslik T, Falchi A. Prevalence of gastrointestinal symptoms in patients with influenza, clinical significance, and pathophysiology of human influenza viruses in faecal samples: what do we know? Virol J 2015; 12:215. [PMID: 26651485 PMCID: PMC4676820 DOI: 10.1186/s12985-015-0448-4] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 12/04/2015] [Indexed: 12/14/2022] Open
Abstract
This review provides for the first time an assessment of the current understanding about the occurrence and the clinical significance of gastrointestinal (GI) symptoms in influenza patients, and their correlation with the presence of human influenza viruses in stools of patients with confirmed influenza virus infection. Studies exploring how human influenza viruses spread to the patient’s GI tract after a primary respiratory infection have been summarized. We conducted a systematic search of published peer-reviewed literature up to June 2015 with regard to the above-mentioned aspects, focusing on human influenza viruses (A(H1N1), A(H1N1)pdm09, A(H3N2), and B). Forty-four studies were included in this systematic review and meta-analysis. The pooled prevalence of any digestive symptoms ranged from 30.9 % (95 % CI, 9.8 to 57.5; I2 = 97.5 %) for A(H1N1)pdm09 to 2.8 % (95 % CI, 0.6 to 6.5; I2 = 75.4 %) for A(H1N1). The pooled prevalence of influenza viruses in stool was 20.6 % (95 % CI, 8.9 to 35.5; I2 = 96.8 %), but their correlation with GI symptoms has rarely been explored. The presence of viral RNA in stools because of haematogenous dissemination to organs via infected lymphocytes is likely, but the potential to cause direct intestinal infection and faecal–oral transmission warrants further investigation. This review highlights the gaps in our knowledge, and the high degree of uncertainty about the prevalence and significance of GI symptoms in patients with influenza and their correlation with viral RNA positivity in stool because of the high level of heterogeneity among studies.
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Affiliation(s)
- Laetitia Minodier
- EA 7310, laboratory of virology, University of Corsica-Inserm, 20250, Corte, France.
| | - Remi N Charrel
- Aix Marseille Université, IRD French Institute of Research for Development, INSERM U1207, EHESP French School of Public Health, EPV UMR_D 190 "Emergence des Pathologies Virales", & IHU Méditerranée Infection, APHM Public Hospitals of Marseille, Marseille, France.
| | - Pierre-Emmanuel Ceccaldi
- Unité EPVO, Institut Pasteur, Paris-UMR CNRS 3569-Université Paris Diderot, Paris Sorbonne Cité, Cellule Pasteur, Paris, France.
| | - Sylvie van der Werf
- Unit of Molecular Genetics of RNA viruses, Institut Pasteur-UMR CNRS 3569-Université Paris Diderot-Sorbonne Paris Cité, Paris, France. .,Coordinating Center of the National Reference Center for influenza viruses, National Influenza Center (Northern-France), Institut Pasteur, Paris, France.
| | - Thierry Blanchon
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Paris, France. .,INSERM, UMR_S 1136, Paris, France.
| | - Thomas Hanslik
- INSERM, UMR_S 1136, Paris, France. .,Université Versailles Saint Quentin en Yvelines, UFR de Médecine Paris-Ile-de-France-Ouest, 9 boulevard d'Alembert, 78280, Guyancourt, France. .,Service de médecine interne, Hôpital Ambroise Paré, Assistance Publique-Hôpitaux de Paris, 92100, Boulogne Billancourt, France.
| | - Alessandra Falchi
- EA 7310, laboratory of virology, University of Corsica-Inserm, 20250, Corte, France.
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9
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Goto H, Ihira H, Morishita K, Tsuchiya M, Ohta K, Yumine N, Tsurudome M, Nishio M. Enhanced growth of influenza A virus by coinfection with human parainfluenza virus type 2. Med Microbiol Immunol 2015; 205:209-18. [PMID: 26582554 PMCID: PMC7086786 DOI: 10.1007/s00430-015-0441-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 11/08/2015] [Indexed: 12/18/2022]
Abstract
It has been reported that dual or multiple viruses can coinfect epithelial cells of the respiratory tract. However, little has been reported on in vitro interactions of coinfected viruses. To explore how coinfection of different viruses affects their biological property, we examined growth of influenza A virus (IAV) and human parainfluenza virus type 2 (hPIV2) during coinfection of Vero cells. We found that IAV growth was enhanced by coinfection with hPIV2. The enhanced growth of IAV was not reproduced by coinfection with an hPIV2 mutant with reduced cell fusion activity, or by ectopic expression of the V protein of hPIV2. In contrast, induction of cell fusion by ectopic expression of the hPIV2 HN and F proteins augments IAV growth. hPIV2 coinfection supported IAV growth in cells originated from the respiratory epithelium. The enhancement correlated closely with cell fusion ability of hPIV2 in those cells. These results indicate that cell fusion induced by hPIV2 infection is beneficial to IAV replication and that enhanced viral replication by coinfection with different viruses can modify their pathological consequences.
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Affiliation(s)
- Hideo Goto
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Hironobu Ihira
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Keiichi Morishita
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Mitsuki Tsuchiya
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Keisuke Ohta
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Natsuko Yumine
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Masato Tsurudome
- Department of Microbiology and Molecular Genetics, Mie University Graduate School of Medicine, Mie, Japan
| | - Machiko Nishio
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan.
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10
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Sonnberg S, Webby RJ, Webster RG. Natural history of highly pathogenic avian influenza H5N1. Virus Res 2013; 178:63-77. [PMID: 23735535 PMCID: PMC3787969 DOI: 10.1016/j.virusres.2013.05.009] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 05/03/2013] [Accepted: 05/20/2013] [Indexed: 12/27/2022]
Abstract
The ecology of highly pathogenic avian influenza (HPAI) H5N1 has significantly changed from sporadic outbreaks in terrestrial poultry to persistent circulation in terrestrial and aquatic poultry and potentially in wild waterfowl. A novel genotype of HPAI H5N1 arose in 1996 in Southern China and through ongoing mutation, reassortment, and natural selection, has diverged into distinct lineages and expanded into multiple reservoir hosts. The evolution of Goose/Guangdong-lineage highly pathogenic H5N1 viruses is ongoing: while stable interactions exist with some reservoir hosts, these viruses are continuing to evolve and adapt to others, and pose an un-calculable risk to sporadic hosts, including humans.
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Affiliation(s)
- Stephanie Sonnberg
- Department of Infectious Diseases St. Jude Children's Research Hospital 262 Danny Thomas Drive MS 330, Memphis, TN, 38103 USA
| | - Richard J. Webby
- Department of Infectious Diseases St. Jude Children's Research Hospital 262 Danny Thomas Drive MS 330, Memphis, TN, 38103 USA
| | - Robert G. Webster
- corresponding author, Department of Infectious Diseases St. Jude Children's Research Hospital 262 Danny Thomas Drive MS 330, Memphis, TN, 38103 USA Tel +1 901 595 3400 Fax +1 901 595 8559
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11
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Ni F, Kondrashkina E, Wang Q. Structural basis for the divergent evolution of influenza B virus hemagglutinin. Virology 2013; 446:112-22. [PMID: 24074573 DOI: 10.1016/j.virol.2013.07.035] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 07/23/2013] [Accepted: 07/26/2013] [Indexed: 10/26/2022]
Abstract
Influenza A and B viruses are responsible for the severe morbidity and mortality worldwide in annual influenza epidemics. Currently circulating influenza B virus belongs to the B/Victoria or B/Yamagata lineage that was diverged from each other about 30-40 years ago. However, a mechanistic understanding of their divergent evolution is still lacking. Here we report the crystal structures of influenza B/Yamanashi/166/1998 hemagglutinin (HA) belonging to B/Yamagata lineage and its complex with the avian-like receptor analogue. Comparison of these structures with those of undiverged and diverged influenza B virus HAs, in conjunction with sequence analysis, reveals the molecular basis for the divergent evolution of influenza B virus HAs. Furthermore, HAs of diverged influenza B virus strains display much stronger molecular interactions with terminal sialic acid of bound receptors, which may allow for a different tissue tropism for current influenza B viruses, for which further investigation is required.
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Affiliation(s)
- Fengyun Ni
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Department of Bioengineering, Rice University, Houston, TX 77005, USA
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12
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Desbat B, Lancelot E, Krell T, Nicolaï MC, Vogel F, Chevalier M, Ronzon F. Effect of the β-propiolactone treatment on the adsorption and fusion of influenza A/Brisbane/59/2007 and A/New Caledonia/20/1999 virus H1N1 on a dimyristoylphosphatidylcholine/ganglioside GM3 mixed phospholipids monolayer at the air-water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:13675-13683. [PMID: 21981550 DOI: 10.1021/la2027175] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The production protocol of many whole cell/virion vaccines involves an inactivation step with β-propiolactone (BPL). Despite the widespread use of BPL, its mechanism of action is poorly understood. Earlier work demonstrated that BPL alkylates nucleotide bases, but its interaction with proteins has not been studied in depth. In the present study we use ellipsometry to analyze the influence of BPL treatment of two H1N1 influenza strains, A/Brisbane/59/2007 and A/New Caledonia/20/1999, which are used for vaccine production on an industrial scale. Analyses were conducted using a mixed lipid monolayer containing ganglioside GM3, which functions as the viral receptor. Our results show that BPL treatment of both strains reduces viral affinity for the mixed monolayer and also diminishes the capacity of viral domains to self-assemble. In another series of experiments, the pH of the subphase was reduced from 7.4 to 5 to provoke the pH-induced conformational change of hemagglutinin, which occurs following endocytosis into the endosome. In the presence of the native virus the pH decrease caused a reduction in domain size, whereas lipid layer thickness and surface pressure were increased. These observations are consistent with a fusion of the viral membrane with the lipid monolayer. Importantly, this fusion was not observed with adsorbed inactivated virus, which indicates that BPL treatment inhibits the first step of virus-membrane fusion. Our data also indicate that BPL chemically modifies hemagglutinin, which mediates the interaction with GM3.
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Affiliation(s)
- Bernard Desbat
- CBMN, UMR CNRS 5248, Université Bordeaux, IPB, Allée Geoffroy Saint Hilaire 33600 Pessac, France.
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13
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Nakowitsch S, Wolschek M, Morokutti A, Ruthsatz T, Krenn BM, Ferko B, Ferstl N, Triendl A, Muster T, Egorov A, Romanova J. Mutations affecting the stability of the haemagglutinin molecule impair the immunogenicity of live attenuated H3N2 intranasal influenza vaccine candidates lacking NS1. Vaccine 2011; 29:3517-24. [PMID: 21406268 DOI: 10.1016/j.vaccine.2011.02.100] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 02/18/2011] [Accepted: 02/28/2011] [Indexed: 12/20/2022]
Abstract
The isolation and cultivation of human influenza viruses in embryonated hen eggs or cell lines often leads to amino acid substitutions in the haemagglutinin (HA) molecule. We found that the propagation of influenza A H3N2 viruses on Vero cells may trigger the appearance of HA destabilising mutations, affecting viral resistance to low pH or high temperature treatment. Two ΔNS1 reassortants, containing the HA sequences identical to the original human H3N2 influenza virus isolates were constructed. Passages of these viruses on Vero cells led to the appearance of single mutations in the HA(1) L194P or HA(2) G75R subunits that impaired virus stability. The original HA sequences and the stable phenotypes of the primary isolates were preserved if reassortants were passaged by infection at pH 5.6 and cultivation in medium at pH 6.5. Corresponding ΔNS1 reassortants were compared for their immunogenicity in ferrets upon intranasal immunisation. Vaccine candidates containing HA mutations demonstrated significantly lower immunogenicity compared to those without mutations. Thus, the retaining of the original HA sequences of human viruses during vaccine production might be crucial for the efficacy of live attenuated influenza vaccines.
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Affiliation(s)
- Sabine Nakowitsch
- Avir Green Hills Biotechnology AG, Forsthausgasse 11, A-1200 Vienna, Austria
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14
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Kim CS, Epand RF, Leikina E, Epand RM, Chernomordik LV. The final conformation of the complete ectodomain of the HA2 subunit of influenza hemagglutinin can by itself drive low pH-dependent fusion. J Biol Chem 2011; 286:13226-34. [PMID: 21292763 DOI: 10.1074/jbc.m110.181297] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
One of the best characterized fusion proteins, the influenza virus hemagglutinin (HA), mediates fusion between the viral envelope and the endosomal membrane during viral entry into the cell. In the initial conformation of HA, its fusogenic subunit, the transmembrane protein HA2, is locked in a metastable conformation by the receptor-binding HA1 subunit of HA. Acidification in the endosome triggers HA2 refolding toward the final lowest energy conformation. Is the fusion process driven by this final conformation or, as often suggested, by the energy released by protein restructuring? Here we explored structural properties as well as the fusogenic activity of the full sized trimeric HA2(1-185) (here called HA2*) that presents the final conformation of the HA2 ectodomain. We found HA2* to mediate fusion between lipid bilayers and between biological membranes in a low pH-dependent manner. Two mutations known to inhibit HA-mediated fusion strongly inhibited the fusogenic activity of HA2*. At surface densities similar to those of HA in the influenza virus particle, HA2* formed small fusion pores but did not expand them. Our results confirm that the HA1 subunit responsible for receptor binding as well as the transmembrane and cytosolic domains of HA2 is not required for fusion pore opening and substantiate the hypothesis that the final form of HA2 is more important for fusion than the conformational change that generates this form.
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Affiliation(s)
- Chang Sup Kim
- Department of Biotechnology, Division of Applied Chemistry and Biotechnology, Hanbat National University, Daejeon 305-719, South Korea.
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15
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Pinsky BA, Mix S, Rowe J, Ikemoto S, Baron EJ. Long-term shedding of influenza A virus in stool of immunocompromised child. Emerg Infect Dis 2010; 16:1165-7. [PMID: 20587197 PMCID: PMC3321893 DOI: 10.3201/eid1607.091248] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
In immunocompromised patients, influenza infection may progress to prolonged viral shedding from the respiratory tract despite antiviral therapy. We describe chronic influenza A virus infection in an immunocompromised child who had prolonged shedding of culturable influenza virus in stool.
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16
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Statement on Food safety considerations of novel H1N1 influenza virus infections in humans. EFSA J 2010. [DOI: 10.2903/j.efsa.2010.1629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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17
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Greatorex JS, Page RF, Curran MD, Digard P, Enstone JE, Wreghitt T, Powell PP, Sexton DW, Vivancos R, Nguyen-Van-Tam JS. Effectiveness of common household cleaning agents in reducing the viability of human influenza A/H1N1. PLoS One 2010; 5:e8987. [PMID: 20126543 PMCID: PMC2813869 DOI: 10.1371/journal.pone.0008987] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 01/12/2010] [Indexed: 12/03/2022] Open
Abstract
Background In the event of an influenza pandemic, the majority of people infected will be nursed at home. It is therefore important to determine simple methods for limiting the spread of the virus within the home. The purpose of this work was to test a representative range of common household cleaning agents for their effectiveness at killing or reducing the viability of influenza A virus. Methodology/Principal Findings Plaque assays provided a robust and reproducible method for determining virus viability after disinfection, while a National Standard influenza virus RT-PCR assay (VSOP 25, www.hpa-standardmethods.org.uk) was adapted to detect viral genome, and a British Standard (BS:EN 14476:2005) was modified to determine virus killing. Conclusions/Significance Active ingredients in a number of the cleaning agents, wipes, and tissues tested were able to rapidly render influenza virus nonviable, as determined by plaque assay. Commercially available wipes with a claimed antiviral or antibacterial effect killed or reduced virus infectivity, while nonmicrobiocidal wipes and those containing only low concentrations (<5%) of surfactants showed lower anti-influenza activity. Importantly, however, our findings indicate that it is possible to use common, low-technology agents such as 1% bleach, 10% malt vinegar, or 0.01% washing-up liquid to rapidly and completely inactivate influenza virus. Thus, in the context of the ongoing pandemic, and especially in low-resource settings, the public does not need to source specialized cleaning products, but can rapidly disinfect potentially contaminated surfaces with agents readily available in most homes.
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Affiliation(s)
- Jane S Greatorex
- Health Protection Agency, Addenbrookes Hospital, Cambridge, United Kingdom
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18
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Shahid MA, Abubakar M, Hameed S, Hassan S. Avian influenza virus (H5N1); effects of physico-chemical factors on its survival. Virol J 2009; 6:38. [PMID: 19327163 PMCID: PMC2670273 DOI: 10.1186/1743-422x-6-38] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 03/28/2009] [Indexed: 11/23/2022] Open
Abstract
Present study was performed to determine the effects of physical and chemical agents on infective potential of highly pathogenic avian influenza (HPAI) H5N1 (local strain) virus recently isolated in Pakistan during 2006 outbreak. H5N1 virus having titer 108.3 ELD50/ml was mixed with sterilized peptone water to get final dilution of 4HA units and then exposed to physical (temperature, pH and ultraviolet light) and chemical (formalin, phenol crystals, iodine crystals, CID 20, virkon®-S, zeptin 10%, KEPCIDE 300, KEPCIDE 400, lifebuoy, surf excel and caustic soda) agents. Harvested amnio-allantoic fluid (AAF) from embryonated chicken eggs inoculated with H5N1 treated virus (0.2 ml/egg) was subjected to haemagglutination (HA) and haemagglutination inhibition (HI) tests. H5N1 virus lost infectivity after 30 min at 56°C, after 1 day at 28°C but remained viable for more than 100 days at 4°C. Acidic pH (1, 3) and basic pH (11, 13) were virucidal after 6 h contact time; however virus retained infectivity at pH 5 (18 h), 7 and 9 (more than 24 h). UV light was proved ineffectual in inactivating virus completely even after 60 min. Soap (lifebuoy®), detergent (surf excel®) and alkali (caustic soda) destroyed infectivity after 5 min at 0.1, 0.2 and 0.3% dilution. All commercially available disinfectants inactivated virus at recommended concentrations. Results of present study would be helpful in implementing bio-security measures at farms/hatcheries levels in the wake of avian influenza virus (AIV) outbreak.
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19
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Characterization of Lassa virus cell entry and neutralization with Lassa virus pseudoparticles. J Virol 2009; 83:3228-37. [PMID: 19153226 DOI: 10.1128/jvi.01711-08] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The cell entry and humoral immune response of the human pathogen Lassa virus (LV), a biosafety level 4 (BSL4) Old World arenavirus, are not well characterized. LV pseudoparticles (LVpp) are a surrogate model system that has been used to decipher factors and routes involved in LV cell entry under BSL2 conditions. Here, we describe LVpp, which are highly infectious, with titers approaching those obtained with pseudoparticles displaying G protein of vesicular stomatitis virus and their the use for the characterization of LV cell entry and neutralization. Upon cell attachment, LVpp utilize endocytic vesicles for cell entry as described for many pH-dependent viruses. However, the fusion of the LV glycoproteins is activated at unusually low pH values, with optimal fusion occurring between pH 4.5 and 3, a pH range at which fusion characteristics of viral glycoproteins have so far remained largely unexplored. Consistent with a shifted pH optimum for fusion activation, we found wild-type LV and LVpp to display a remarkable resistance to exposure to low pH. Finally, LVpp allow the fast and quantifiable detection of neutralizing antibodies in human and animal sera and will thus facilitate the study of the humoral immune response in LV infections.
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20
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Ohnishi SI. Chapter 9 Fusion of Viral Envelopes with Cellular Membranes. CURRENT TOPICS IN MEMBRANES AND TRANSPORT 2008; 32:257-296. [PMID: 32287479 PMCID: PMC7146812 DOI: 10.1016/s0070-2161(08)60137-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
This chapter reviews some characteristic features of membrane fusion activity for each virus and discusses the mechanisms of membrane fusion, especially low pH-induced membrane fusion. It concentrates on the interaction of the hydrophobic segment with the target cell membrane lipid bilayer and suggests the entrance of the segment into the lipid bilayer hydrophobic core as a key step in fusion. The envelope is a lipid bilayer membrane with the virus specific glycoproteins spanning it. The bilayer originates from the host cell membrane and has a lipid composition and transbilayer distribution quite similar to the host's. The viral glycoproteins have the functions of binding to the target cell surface and fusion with the cell membranes. The two functions are carried by a single glycoprotein in influenza virus (HA), vesicular stomatitis virus (VSV) G glycoprotein, and Semliki Forest virus SFV E glycoprotein. In Sendai virus (HVJ), the functions are carried by separate glycoproteins, hemagglutinin-neuraminidase (HN) for binding and fusion glycoprotein (F) for fusion. When viruses encounter target cells, they first bind to the cell surface through an interaction of the viral glycoprotein with receptors.
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Affiliation(s)
- Shun-Ichi Ohnishi
- Department of Biophysics Facurlty of Science Kyoto University Sakyo-ku. Kyoto 606, Japan
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21
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Meckes DG, Wills JW. Dynamic interactions of the UL16 tegument protein with the capsid of herpes simplex virus. J Virol 2007; 81:13028-36. [PMID: 17855514 PMCID: PMC2169088 DOI: 10.1128/jvi.01306-07] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The UL16 tegument protein of herpes simplex virus is conserved throughout the herpesvirus family. It has been reported to be capsid associated and may be involved in budding by providing an interaction with the membrane-bound UL11 protein. UL16 has been shown to be present in all the major locations that capsids are found (i.e., the nucleus, cytoplasm, and virions), but whether it is actually capsid associated in each of these has not been reported. Therefore, capsids were purified from each compartment, and it was found that UL16 was present on cytoplasmic but not nuclear capsids. In extracellular virions, the majority of UL16 (87%) was once again not capsid associated, which suggests that the interaction is transient during egress. Because herpes simplex virus (HSV) buds into the acidic compartment of the trans-Golgi network (TGN), the effect of pH on the interaction was examined. The amount of capsid-associated UL16 dramatically increased when extracellular virions were exposed to mildly acidic medium (pH 5.0 to 5.5), and this association was fully reversible. After budding into the TGN, capsid and tegument proteins also encounter an oxidizing environment, which is conducive to disulfide bond formation. UL16 contains 20 cysteines, including five that are conserved within a putative zinc finger. Any free cysteines that are involved in the capsid interaction or release mechanism of UL16 would be expected to be modified by N-ethylmaleimide, and, consistent with this, the amount of capsid-associated UL16 dramatically increased when virions were incubated with this compound. Taken together, these data suggest a transient interaction between UL16 and capsids, possibly modified in the acidic compartment of secretory vesicles and requiring a release mechanism that involves cysteines.
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Affiliation(s)
- David G Meckes
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, 500 University Drive, P.O. Box 850, Hershey, PA 17036, USA
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22
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De Benedictis P, Beato MS, Capua I. Inactivation of avian influenza viruses by chemical agents and physical conditions: a review. Zoonoses Public Health 2007; 54:51-68. [PMID: 17348909 DOI: 10.1111/j.1863-2378.2007.01029.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The recent outbreaks of avian influenza (AI) worldwide have highlighted the difficulties in controlling this disease both in developed and in developing countries. Biosecurity is considered the most important tool to prevent and control AI. In certain areas of the world, AI has become endemic and the recent outbreaks in Europe and Africa show that the epidemiological situation is evolving in an unprecedented way. The consequences of this situation are economic losses to the poultry industry, food security issues in developing countries and a serious threat to human health, due to the direct consequences of AI infection in humans, and more alarmingly due to the risk of the generation of a new pandemic virus from the animal reservoir. In this paper, the physical and chemical methods of inactivating AI viruses are reviewed, with particular emphasis on the practicalities of using such methods in the poultry industry.
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Affiliation(s)
- P De Benedictis
- OIE, FAO and National Reference Laboratory for Avian Influenza and Newcastle Disease, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020 Legnaro, Padova, Italy
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23
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Korte T, Ludwig K, Huang Q, Rachakonda PS, Herrmann A. Conformational change of influenza virus hemagglutinin is sensitive to ionic concentration. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 36:327-35. [PMID: 17211621 DOI: 10.1007/s00249-006-0116-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 11/03/2006] [Accepted: 11/17/2006] [Indexed: 11/29/2022]
Abstract
The homotrimeric spike glycoprotein hemagglutinin (HA) of influenza virus undergoes a low pH-mediated conformational change which mediates the fusion of the viral envelope with the target membrane. Previous approaches predict that the interplay of electrostatic interactions between and within HA subunits, HA 1 and HA2, are essential for the metastability of the HA ectodomain. Here, we show that suspension media of low ionic concentration promote fusion of fluorescent labelled influenza virus X31 with erythrocyte ghosts and with ganglioside containing liposomes. By measuring the low pH mediated inactivation of the fusion competence of HA and the Proteinase K sensitivity of low pH incubated HA we show that the conformational change is promoted by low ionic concentration. We surmise that electrostatic attraction within the HA ectodomain is weakened by lowering the ionic concentration facilitating the conformational change at low pH.
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Affiliation(s)
- Thomas Korte
- Institute of Biology, Molecular Biophysics, Humboldt University, Berlin 10115, Germany
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24
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Loyter A, Citovsky V, Blumenthal R. The use of fluorescence dequenching measurements to follow viral membrane fusion events. METHODS OF BIOCHEMICAL ANALYSIS 2006; 33:129-64. [PMID: 3128721 DOI: 10.1002/9780470110546.ch4] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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25
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Whitbeck JC, Zuo Y, Milne RSB, Cohen GH, Eisenberg RJ. Stable association of herpes simplex virus with target membranes is triggered by low pH in the presence of the gD receptor, HVEM. J Virol 2006; 80:3773-80. [PMID: 16571794 PMCID: PMC1440471 DOI: 10.1128/jvi.80.8.3773-3780.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Using a liposome-binding assay, we investigated the requirements for activation of herpes simplex virus (HSV) into a state capable of membrane interaction. Virions were mixed with liposomes along with the ectodomain of one of three gD receptors (HVEMt, nectin-1t, or nectin-2t) and incubated under different pH and temperature conditions. Virions failed to associate with liposomes in the presence of nectin-1 or nectin-2 at any temperature or pH tested. In contrast, HVEMt triggered association of HSV with liposomes at pH 5.3 or 5.0 when incubated at 37 degrees C, suggesting that HVEM binding and mildly acidic pH at a physiological temperature provide coactivation signals, allowing virus association with membranes. Virions incubated with HVEMt at 37 degrees C without liposomes rapidly lost infectivity upon exposure to pH 5.0, suggesting that these conditions lead to irreversible virus inactivation in the absence of target membranes. Consistent with the idea that soluble receptor molecules provide a trigger for HSV entry, HVEMt promoted virus entry into receptor-deficient CHO K1 cells. However, in B78H1 cells, HVEMt promoted virus entry with markedly lower efficiency. Interestingly, HSV entry into receptor-bearing CHO K1 cells has been shown to proceed via a pH-dependent manner, whereas HSV entry into receptor-bearing B78H1 cells is pH independent. Based on these observations, we propose that the changes triggered by HVEM and mildly acidic pH that allow liposome association are similar or identical to changes that occur during pH-dependent HSV entry.
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Affiliation(s)
- J Charles Whitbeck
- School of Dental Medicine, University of Pennsylvania, 4010 Locust Street, Levy Building, Room 212, Philadelphia, Pennsylvania 19104, USA.
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26
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Ksenofontov AL, Kozlovskii VS, Kordyukova LV, Radyukhin VA, Timofeeva AV, Dobrov EN. Determination of concentration and aggregate size in influenza virus preparations from true UV absorption spectra. Mol Biol 2006. [DOI: 10.1134/s0026893306010201] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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27
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Brorson K, Krejci S, Lee K, Hamilton E, Stein K, Xu Y. Bracketed generic inactivation of rodent retroviruses by low pH treatment for monoclonal antibodies and recombinant proteins. Biotechnol Bioeng 2003; 82:321-9. [PMID: 12599259 DOI: 10.1002/bit.10574] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Viral safety is a predominant concern for monoclonal antibodies (mAbs) and other recombinant proteins (RPs) with pharmaceutical applications. Certain commercial purification modules, such as nanofiltration and low-pH inactivation, have been observed to reliably clear greater than 4 log(10) of large enveloped viruses, including endogenous retrovirus. The concept of "bracketed generic clearance" has been proposed for these steps if it could be prospectively demonstrated that viral log(10) reduction value (LRV) is not impacted by operating parameters that can vary, within a reasonable range, between commercial processes. In the case of low-pH inactivation, a common step in mAb purification processes employed after protein A affinity chromatography, these parameters would include pH, time and temperature of incubation, the content of salts, protein concentration, aggregates, impurities, model protein pI, and buffer composition. In this report, we define bracketed generic clearance conditions, using a prospectively defined bracket/matrix approach, where low-pH inactivation consistently achieves >or=4.6 log(10) clearance of xenotropic murine leukemia virus (X-MLV), a model for rodent endogenous retrovirus. The mechanism of retrovirus inactivation by low-pH treatment was also investigated.
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Affiliation(s)
- Kurt Brorson
- Division of Monoclonal Antibodies, Center for Biologics Evaluation and Research, Food and Drug Administration, 8800 Rockville Pike, Bethesda, Maryland 20892, USA
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28
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Bonavia A, Zelus BD, Wentworth DE, Talbot PJ, Holmes KV. Identification of a receptor-binding domain of the spike glycoprotein of human coronavirus HCoV-229E. J Virol 2003; 77:2530-8. [PMID: 12551991 PMCID: PMC141070 DOI: 10.1128/jvi.77.4.2530-2538.2003] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human coronavirus HCoV-229E uses human aminopeptidase N (hAPN) as its receptor (C. L. Yeager et al., Nature 357:420-422, 1992). To identify the receptor-binding domain of the viral spike glycoprotein (S), we expressed soluble truncated histidine-tagged S glycoproteins by using baculovirus expression vectors. Truncated S proteins purified by nickel affinity chromatography were shown to be glycosylated and to react with polyclonal anti-HCoV-229E antibodies and monoclonal antibodies to the viral S protein. A truncated protein (S(547)) that contains the N-terminal 547 amino acids bound to 3T3 mouse cells that express hAPN but not to mouse 3T3 cells transfected with empty vector. Binding of S(547) to hAPN was blocked by an anti-hAPN monoclonal antibody that inhibits binding of virus to hAPN and blocks virus infection of human cells and was also blocked by polyclonal anti-HCoV-229E antibody. S proteins that contain the N-terminal 268 or 417 amino acids did not bind to hAPN-3T3 cells. Antibody to the region from amino acid 417 to the C terminus of S blocked binding of S(547) to hAPN-3T3 cells. Thus, the data suggest that the domain of the spike protein between amino acids 417 and 547 is required for the binding of HCoV-229E to its hAPN receptor.
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Affiliation(s)
- Aurelio Bonavia
- Department of Microbiology Molecular Biology Program, University of Colorado Health Sciences Center, 4200 E 9th Avenue, Denver, CO 80262, USA
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29
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Affiliation(s)
- Pierre Bonnafous
- Crucell Holland BV, Archimedesweg 4, P.O. Box 2048, Leiden, The Netherlands
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Leikina E, Ramos C, Markovic I, Zimmerberg J, Chernomordik LV. Reversible stages of the low-pH-triggered conformational change in influenza virus hemagglutinin. EMBO J 2002; 21:5701-10. [PMID: 12411488 PMCID: PMC131056 DOI: 10.1093/emboj/cdf559] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The refolding of the prototypic fusogenic protein hemagglutinin (HA) at the pH of fusion is considered to be a concerted and irreversible discharge of a loaded spring, with no distinct intermediates between the initial and final conformations. Here, we show that HA refolding involves reversible conformations with a lifetime of minutes. After reneutralization, low pH-activated HA returns from the conformations wherein both the fusion peptide and the kinked loop of the HA2 subunit are exposed, but the HA1 subunits have not yet dissociated, to a structure indistinguishable from the initial one in functional, biochemical and immunological characteristics. The rate of the transition from reversible conformations to irreversible refolding depends on the pH and on the presence of target membrane. Importantly, recovery of the initial conformation is blocked by the interactions between adjacent HA trimers. The existence of the identified reversible stage of refolding can be crucial for allowing multiple copies of HA to synchronize their release of conformational energy, as required for fusion.
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Affiliation(s)
| | | | - Ingrid Markovic
- Laboratory of Cellular and Molecular Biophysics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA
Present address: Division of Monoclonal Antibodies, Office of Therapeutics Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA Corresponding author e-mail:
| | | | - Leonid V. Chernomordik
- Laboratory of Cellular and Molecular Biophysics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA
Present address: Division of Monoclonal Antibodies, Office of Therapeutics Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA Corresponding author e-mail:
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31
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Shental-Bechor D, Danieli T, Henis Y, Ben-Tal N. Long-range effects on the binding of the influenza HA to receptors are mediated by changes in the stability of a metastable HA conformation. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1565:81-9. [PMID: 12225855 DOI: 10.1016/s0005-2736(02)00511-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
X-ray studies show that influenza hemagglutinin (HA) forms an elongated structure connecting the influenza virus at one end to cell-surface receptors at the other. At neutral pH, the 20 N-terminal residues of HA2-referred to as the fusion peptide-are buried in a hydrophobic pocket, about 100 A away from the receptor-binding site, and thus seem unlikely to affect HA binding to the receptor. To test this assumption, we mutated residues in the fusion peptide, heterologically expressed the mutated proteins in COS7 cells, and examined their ability to bind fluorescently labeled red blood cells (RBCs). Surprisingly, a significantly reduced binding was recorded for some of the mutants. Ample experimental data indicate that HA has at least two forms: the native structure at neutral pH (N) that is metastable and the fusogenic form (F), observed at low pH, which is stable. Thus, a simple interpretation of our data is that HA can bind to its receptors at the RBC surface in the N form much more effectively than in the F (or in any other stable) form and that the altered binding properties are due to destabilizing effects of the mutations on the N form. That is, some of the mutations involve reduction in the free energy barrier between the N and F forms. This, in turn, leads to reduction in the population of the N form, which is the only form capable of binding to the cell-surface receptors. To explore this possibility, we estimated the stability free energy difference between HA wild-type (wt) and mutants in the N form using an empirical surface tension coefficient. The calculated stability differences correlated well with the measured binding, supporting the above interpretation. Our results are examined taking into account the available experimental data on the affinity of different soluble and membrane-attached forms of HA to its receptors.
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Affiliation(s)
- Dalit Shental-Bechor
- Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
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32
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Epand RM, Epand RF. Thermal denaturation of influenza virus and its relationship to membrane fusion. Biochem J 2002; 365:841-8. [PMID: 11994048 PMCID: PMC1222734 DOI: 10.1042/bj20020290] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2002] [Revised: 04/23/2002] [Accepted: 05/07/2002] [Indexed: 01/14/2023]
Abstract
The X-31 strain of influenza virus was studied by differential scanning calorimetry (DSC), CD and SDS/PAGE analysis as a function of both temperature and pH. A bromelain-treated virus was also studied by these methods. The major transition observed in the intact virus was a result of the denaturation of the haemagglutinin (HA) protein. At pH 7.4, this transition was similar in the intact virus and the isolated HA, but was absent in the bromelain-treated virus. However, at pH 5 the denaturation temperature and enthalpy were both higher for HA in the virus than in the isolated protein, indicating that HA interacts with other molecular components in the intact virus. The transition observed by DSC occurs at a higher temperature than does the thermal transition observed by CD. The temperature of the CD transition coincides with the temperature at which the fusogenicity of the virus increases, and probably corresponds to the formation of an extended coiled-coil conformation. Analysis by SDS/PAGE at neutral pH under non-reducing conditions demonstrates a selective loss of the HA protein trimer, resulting in the formation of aggregates in the range of temperatures of 55 to 70 degrees C. In contrast, at acidic pH, the HA protein is largely in the monomeric form at 25 degrees C, and there is little change with temperature. There is thus a weakening of the quaternary structure of HA at acidic pH prior to heating. At the temperature at which the virus exhibits an increased fusogenicity at neutral pH, there is a loss of secondary structure and a beginning of a destabilization of the trimeric form of HA. This temperature is lower than that required for the major endothermic peak observed in DSC experiments. The results demonstrate that there is no kinetically trapped high-energy form of HA at neutral pH.
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Affiliation(s)
- Richard M Epand
- Department of Biochemistry, McMaster Health Sciences Centre, Hamilton, ON L8N 3Z5, Canada.
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33
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Edwards MJ, Dimmock NJ. Hemagglutinin 1-specific immunoglobulin G and Fab molecules mediate postattachment neutralization of influenza A virus by inhibition of an early fusion event. J Virol 2001; 75:10208-18. [PMID: 11581389 PMCID: PMC114595 DOI: 10.1128/jvi.75.21.10208-10218.2001] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In standard neutralization (STAN), virus and antibody are reacted together before inoculation of target cells, and inhibition of almost any of the processes concerned in the early interaction of virus and cell, including inhibition of virus attachment to cell receptors, can be the cause of neutralization by a particular monoclonal antibody (MAb). To simplify the interpretation of antibody action, we carried out a study of postattachment neutralization (PAN), where virus is allowed to attach to target cells before neutralizing antibody is introduced. We used influenza virus A/PR/8/34 (H1N1) and monoclonal immunoglobulin G (IgG) molecules and their Fabs specific to antigenic sites Sb (tip), Ca2 (loop), and Cb (hinge) of the hemagglutinin 1 (HA1) protein. All IgGs and Fabs gave PAN, although with reduced efficiency compared with STAN. Thus, bivalent binding of antibody was not essential for PAN. By definition, none of these MAbs gave PAN by inhibiting virus attachment, and they did not elute attached virus from the target cell or inhibit endocytosis of virus. However, virus-cell fusion, as demonstrated by R18 fluorescence dequenching or hemolysis of red blood cells, was inhibited in direct proportion to neutralization and in a dose-dependent manner and was thus likely to be responsible for the observed neutralization. However, to get PAN, it was necessary to inhibit the activation of the prefusion intermediate, the earliest known form on the fusion pathway that is created when virus is incubated at pH 5 and 4 degrees C. PAN antibodies may act by binding HA trimers in contact with the cell and/or trimers in the immediate vicinity of the virus-cell contact point and so inhibit the recruitment of additional receptor-HA complexes.
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Affiliation(s)
- M J Edwards
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
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34
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Dormitzer PR, Greenberg HB, Harrison SC. Proteolysis of monomeric recombinant rotavirus VP4 yields an oligomeric VP5* core. J Virol 2001; 75:7339-50. [PMID: 11462006 PMCID: PMC114969 DOI: 10.1128/jvi.75.16.7339-7350.2001] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Rotavirus particles are activated for cell entry by trypsin cleavage of the outer capsid spike protein, VP4, into a hemagglutinin, VP8*, and a membrane penetration protein, VP5*. We have purified rhesus rotavirus VP4, expressed in baculovirus-infected insect cells. Purified VP4 is a soluble, elongated monomer, as determined by analytical ultracentrifugation. Trypsin cleaves purified VP4 at a number of sites that are protected on the virion and yields a heterogeneous group of protease-resistant cores of VP5*. The most abundant tryptic VP5* core is trimmed past the N terminus associated with activation for virus entry into cells. Sequential digestion of purified VP4 with chymotrypsin and trypsin generates homogeneous VP8* and VP5* cores (VP8CT and VP5CT, respectively), which have the authentic trypsin cleavages in the activation region. VP8CT is a soluble monomer composed primarily of beta-sheets. VP5CT forms sodium dodecyl sulfate-resistant dimers. These results suggest that trypsinization of rotavirus particles triggers a rearrangement in the VP5* region of VP4 to yield the dimeric spikes observed in icosahedral image reconstructions from electron cryomicroscopy of trypsinized rotavirus virions. The solubility of VP5CT and of trypsinized rotavirus particles suggests that the trypsin-triggered conformational change primes VP4 for a subsequent rearrangement that accomplishes membrane penetration. The domains of VP4 defined by protease analysis contain all mapped neutralizing epitopes, sialic acid binding residues, the heptad repeat region, and the membrane permeabilization region. This biochemical analysis of VP4 provides sequence-specific structural information that complements electron cryomicroscopy data and defines targets and strategies for atomic-resolution structural studies.
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Affiliation(s)
- P R Dormitzer
- Laboratory of Molecular Medicine, Children's Hospital, Boston, Massachusetts 02115, USA.
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35
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Han X, Tamm LK. A host-guest system to study structure-function relationships of membrane fusion peptides. Proc Natl Acad Sci U S A 2000; 97:13097-102. [PMID: 11069282 PMCID: PMC27184 DOI: 10.1073/pnas.230212097] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We designed a host-guest fusion peptide system, which is completely soluble in water and has a high affinity for biological and lipid model membranes. The guest sequences are those of the fusion peptides of influenza hemagglutinin, which are solubilized by a highly charged unstructured C-terminal host sequence. These peptides partition to the surface of negatively charged liposomes or erythrocytes and elicit membrane fusion or hemolysis. They undergo a conformational change from random coil to an obliquely inserted ( approximately 33 degrees from the surface) alpha-helix on binding to model membranes. Partition coefficients for membrane insertion were measured for influenza fusion peptides of increasing lengths (n = 8, 13, 16, and 20). The hydrophobic contribution to the free energy of binding of the 20-residue fusion peptide at pH 5.0 is -7.6 kcal/mol (1 cal = 4.18 J). This energy is sufficient to stabilize a "stalk" intermediate if a typical number of fusion peptides assemble at the site of membrane fusion. The fusion activity of the fusion peptides increases with each increment in length, and this increase strictly correlates with the hydrophobic binding energy and the angle of insertion.
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Affiliation(s)
- X Han
- Department of Molecular Physiology and Biological Physics and Center for Structural Biology, University of Virginia Health Sciences Center, P.O. Box 800736, Charlottesville, VA 22908-0736, USA
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36
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Han X, Steinhauer DA, Wharton SA, Tamm LK. Interaction of mutant influenza virus hemagglutinin fusion peptides with lipid bilayers: probing the role of hydrophobic residue size in the central region of the fusion peptide. Biochemistry 1999; 38:15052-9. [PMID: 10555988 DOI: 10.1021/bi991232h] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The amino-terminal region of the membrane-anchored subunit of influenza virus hemagglutinin, the fusion peptide, is crucial for membrane fusion of this virus. The peptide is extruded from the interior of the protein and inserted into the lipid bilayer of the target membrane upon induction of a conformational change in the protein by low pH. Although the effects of several mutations in this region on the fusion behavior and the biophysical properties of the corresponding peptides have been studied, the structural requirements for an active fusion peptide have still not been defined. To probe the sensitivity of the fusion peptide structure and function to small hydrophobic perturbations in the middle of the hydrophobic region, we have individually replaced the alanine residues in positions 5 and 7 with smaller (glycine) or bulkier (valine) hydrophobic residues and measured the extent of fusion mediated by these hemagglutinin constructs as well as some biophysical properties of the corresponding synthetic peptides in lipid bilayers. We find that position 5 tolerates a smaller and position 7 a larger hydrophobic side chain. All peptides contained segments of alpha-helical (33-45%) and beta-strand (13-16%) conformation as determined by CD and ATR-FTIR spectroscopy. The order parameters of the peptide helices and the lipid hydrocarbon chains were determined from measurements of the dichroism of the respective infrared absorption bands. Order parameters in the range of 0.0-0.6 were found for the helices of these peptides, which indicate that these peptides are most likely aligned with their alpha-helices at oblique angles to the membrane normal. Some (mostly fusogenic) peptides induced significant increases of the order parameter of the lipid hydrocarbon chains, suggesting that the lipid bilayer becomes more ordered in the presence of these peptides, possibly as a result of dehydration at the membrane surface.
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Affiliation(s)
- X Han
- Department of Molecular Physiology and Biological Physics and Center for Structural Biology, University of Virginia Health Sciences Center, Box 10011, Charlottesville, Virginia 22906-0011, USA
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37
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San Román K, Villar E, Muñoz-Barroso I. Acidic pH enhancement of the fusion of Newcastle disease virus with cultured cells. Virology 1999; 260:329-41. [PMID: 10417267 DOI: 10.1006/viro.1999.9841] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Fusion of the lentogenic strain "Clone 30" of Newcastle disease virus (NDV) with the cell line COS-7 has been studied. Fusion was monitored using the octadecylrhodamine B chloride dequenching assay [Hoekstra, D., de Boer, T., Klappe, K. and Wilschut, J. (1984). Biochemistry 23, 5675-5681]. In the present work, fusion of NDV with COS-7 cells was found to occur in a time- and temperature-dependent fashion. Significant dequenching of the probe occurred at temperatures higher than 28 degrees C. A 20-fold excess of unlabeled virus inhibited fusion by about 53% compared with the control, whereas 62% inhibition of fusion was obtained after digestion of viral glycoproteins with trypsin. The data are discussed in terms of the nonfusion transfer of the probe. In addition, preincubation of cells with 50 mM ammonium chloride or 0.1% sodium azide prevented NDV from fusing with COS-7 cells by about 30% in comparison with the control. The cytopathic effect of NDV infection in cell culture in the presence of ammonium chloride was reduced compared with control. Moreover, viral preincubation at pH 5 yielded a mild inhibition of fusogenic activity. Our results suggest that NDV may use the endocytic pathway as a complementary way of entering cells by direct fusion with the plasma membrane.
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Affiliation(s)
- K San Román
- Departamento de Bioquímica y Biología Molecular, Universidad de Salamanca, Edificio Departamental Lab. 109, Salamanca, 37007, Spain
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38
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Staschke KA, Hatch SD, Tang JC, Hornback WJ, Munroe JE, Colacino JM, Muesing MA. Inhibition of influenza virus hemagglutinin-mediated membrane fusion by a compound related to podocarpic acid. Virology 1998; 248:264-74. [PMID: 9721235 DOI: 10.1006/viro.1998.9273] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Entry of influenza virus into the host cell is dependent on the fusion of the viral envelope with the endosomal membrane and is mediated by a low-pH-induced change of the viral hemagglutinin (HA) to a conformation that is fusogenic. A compound related to podocarpic acid (180299) was identified that inhibits multicycle replication of influenza A/Kawasaki/86 (H1N1) virus in culture. Treatment of Madin-Darby canine kidney (MDCK) cells with 180299 at 1 h before infection resulted in the inhibition of viral protein synthesis. Addition of 20 microgram of 180299/ml at 1 h p.i. had no effect, indicating that 180299 affects an early step of the influenza viral replication cycle. Genetic analysis of reassortants between sensitive and resistant viruses demonstrated that hemagglutinin (HA) conferred the 180299-resistant (180299(r)) phenotype. Twelve independent isolates of influenza A/Kawasaki/86 were selected for resistance to 180299, and sequence analysis revealed that each of these viruses contained amino acid substitutions in the HA. These mutations are dispersed throughout the HA primary amino acid sequence and cluster in one of two regions: the interface between HA1 and HA2 and in a region near the fusion domain of HA2. When compared with the parent virus, the pH-of-inactivation of the resistant mutants was increased by 0.3 to 0.6 pH unit, suggesting that the mutant HAs undergo the conformational change at an elevated pH. Fusion of human erythrocytes to MDCK cells infected with parent influenza A/Kawasaki/86 was inhibited by 180299 (0.1-10 microgram/ml) in a concentration-dependent manner, whereas fusion of erythrocytes to MDCK cells infected with 180299(r) mutants was not affected. These results suggest that 180299 interacts with the neutral pH conformation of influenza A HA and prevents the low-pH-induced change of HA to its fusogenic conformation.
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Affiliation(s)
- K A Staschke
- Lilly Research Laboratories, Indianapolis, Indiana, USA
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39
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Shangguan T, Siegel DP, Lear JD, Axelsen PH, Alford D, Bentz J. Morphological changes and fusogenic activity of influenza virus hemagglutinin. Biophys J 1998; 74:54-62. [PMID: 9449309 PMCID: PMC1299361 DOI: 10.1016/s0006-3495(98)77766-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The kinetics of low-pH induced fusion of influenza virus with liposomes have been compared to changes in the morphology of influenza hemagglutinin (HA). At pH 4.9 and 30 degrees C, the fusion of influenza A/PR/8/34 virus with ganglioside-bearing liposomes was complete within 6 min. Virus preincubated at pH 4.9 and 30 degrees C in the absence of liposomes for 2 or 10 min retained most of its fusion activity. However, fusion activity was dramatically reduced after 30 min, and virtually abolished after a 60-min preincubation. Cryo-electron microscopy showed that the hemagglutinin spikes of virions exposed to pH 4.9 at 30 degrees C for 10 min underwent no major morphological changes. After 30 min, however, the spike morphology changed dramatically, and further changes occurred for up to 60 min after exposure to low pH. Because the morphological changes occur at a rate corresponding to the loss of fusion activity, and because these changes are much slower than the rate at which fusion occurs, we conclude that the morphologically altered HA is inactive with respect to fusion-promoting activity. Molecular modeling studies indicate that the formation of an extended coiled coil within the HA trimer, as proposed for HA at low pH, requires a major conformational change in HA, and that the morphological changes we observe are consistent with the formation of an extended coiled coil. These results imply that the crystallographically determined low-pH form of HA does occur in the intact virus, but that this form is not a precursor of viral fusion. It is speculated that the motion to the low-pH form may be responsible for the membrane destabilization leading to fusion.
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Affiliation(s)
- T Shangguan
- Department of Bioscience and Biotechnology, Drexel University, Philadelphia, Pennsylvania 19104, USA
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40
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Carr CM, Chaudhry C, Kim PS. Influenza hemagglutinin is spring-loaded by a metastable native conformation. Proc Natl Acad Sci U S A 1997; 94:14306-13. [PMID: 9405608 PMCID: PMC24954 DOI: 10.1073/pnas.94.26.14306] [Citation(s) in RCA: 333] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Enveloped viruses enter cells by protein-mediated membrane fusion. For influenza virus, membrane fusion is regulated by the conformational state of the hemagglutinin (HA) protein, which switches from a native (nonfusogenic) structure to a fusion-active (fusogenic) conformation when exposed to the acidic environment of the cellular endosome. Here we demonstrate that destabilization of HA at neutral pH, with either heat or the denaturant urea, triggers a conformational change that is biochemically indistinguishable from the change triggered by low pH. In each case, the conformational change is coincident with induction of membrane-fusion activity, providing strong evidence that the fusogenic structure is formed. These results indicate that the native structure of HA is trapped in a metastable state and that the fusogenic conformation is released by destabilization of native structure. This strategy may be shared by other enveloped viruses, including those that enter the cell at neutral pH, and could have implications for understanding the membrane-fusion step of HIV infection.
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Affiliation(s)
- C M Carr
- Howard Hughes Medical Institute, Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Nine Cambridge Center, Cambridge, MA 02142, USA
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41
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Jiricek R, Schwarz G, Stegmann T. Pores formed by influenza hemagglutinin. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1330:17-28. [PMID: 9375809 DOI: 10.1016/s0005-2736(97)00134-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Low pH-induced fusion mediated by the hemagglutinin (HA) of influenza virus involves a conformational change in the protein that leads to the insertion of a "fusion peptide" of the protein into the target membrane. It has been suggested that this insertion, aided by the formation of a complex of multiple HA trimers, would lead to perturbation of the bilayer structure of the membrane, initiating fusion. Here we present data showing that the interaction of the bromelain released ectodomain of the protein (BHA) with liposomal membranes at low pH leads to pore formation, at least at low temperatures. Strongly temperature-dependent low pH-induced inactivation of BHA resulted in a complete lack of activity of BHA above 10 degrees C. Even at 0 degrees C, only about 5% of the BHA participated in pore formation. Viral HA was less rapidly inactivated and still induced pores at 37 degrees C. BHA-induced pore formation showed a sigmoidal time course. Once BHA had formed a pore in one liposome, it did not form a pore in a further liposome. Quantitative analysis of pore formation indicated that one single BHA trimer sufficed to produce a pore. These data indicate that fusion peptide insertion perturbs the membrane and that the formation of a complex of trimers is not a prerequisite for the perturbation.
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Affiliation(s)
- R Jiricek
- Department of Biophysical Chemistry, Biozentrum of the University of Basel, Switzerland
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42
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Razinkov VI, Hernandez-Jimenez EI, Mikhalyov II, Cohen FS, Molotkovsky JG. New fluorescent lysolipids: preparation and selective labeling of inner liposome leaflet. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1329:149-158. [PMID: 9370252 DOI: 10.1016/s0005-2736(97)00103-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Two new fluorescent lysophosphatidylcholine probes have been synthesized for use as a donor-acceptor pair in fluorescence resonance energy transfer (FRET): 9-anthrylvinyl (LAPC) as donor and 3-perylenoyl (LPPC) as acceptor. The partition coefficients between membrane and aqueous phases were 8.3 x 10(5) and 10.5 x 10(5) for LAPC and LPPC, respectively. The inner leaflets of unilamellar lipid vesicles were labeled with these probes to assess conservation of membrane sidedness after membrane fusion. After medium-sized unilamellar vesicles (MUV) were prepared with a probe in both leaflets, probe in the outer leaflet was removed by repeatedly washing with an excess of unlabeled giant unilamellar vesicles (GUV). MUV and GUV were separated by centrifugation. The probes did not flip-flop across bilayers at 25 degrees C for at least 12 h. MUV containing the ganglioside GT1b were labeled with the LAPC/LPPC pair in the inner leaflet and incubated for 30 min at neutral pH with influenza virus. Fusion was triggered by acidification to pH 5.0 and was monitored by an increase in donor fluorescence in a FRET assay. When the inner leaflets of MUV were labeled by LAPC only, its fluorescence did not change after fusion. However, the fluorescence decreased by 60% when the LAPC was removed from the outer leaflets of the fused membranes by repeated washings with GUV. We conclude that the lipids of the inner and outer leaflets of the fused MUV/virus complexes intermixed.
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Affiliation(s)
- V I Razinkov
- Frumkin Institute of Electrochemistry, Russian Academy of Sciences, Moscow
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43
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Kretzschmar E, Buonocore L, Schnell MJ, Rose JK. High-efficiency incorporation of functional influenza virus glycoproteins into recombinant vesicular stomatitis viruses. J Virol 1997; 71:5982-9. [PMID: 9223488 PMCID: PMC191854 DOI: 10.1128/jvi.71.8.5982-5989.1997] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We derived recombinant vesicular stomatitis virus (VSV) expressing either influenza virus hemagglutinin (HA) or neuraminidase (NA) glycoproteins from extra genes inserted in the viral genome. The HA protein was expressed from a site downstream of the VSV glycoprotein (G) gene, while NA protein was expressed from a site upstream of the VSV G gene. The HA protein was expressed at lower levels than the VSV G protein, while the NA protein was expressed at higher levels, as expected from the gradient of VSV transcription that follows the gene order. The HA and NA proteins were transported to the cell surface and were functional as demonstrated by hemadsorption, hemolysis, and NA assays. Biochemical analysis showed that both HA and NA proteins were incorporated into VSV particles at high levels, although there was a preference for incorporation of the VSV G protein over either of the influenza virus proteins. Immunoelectron microscopy of the recombinants showed that the particles derived from the recombinants were mosaics carrying both the VSV G protein and the influenza virus membrane glycoproteins. These results extend earlier studies showing incorporation of the cellular glycoprotein CD4 and two other viral glycoproteins into VSV particles. Our results indicate that there is significant space in the VSV membrane that can accommodate foreign membrane proteins and that the foreign protein can represent as much as 35% of the total protein in the viral envelope. Incorporation of foreign proteins into VSV virions can, in many cases, occur passively in the absence of specific incorporation signals.
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Affiliation(s)
- E Kretzschmar
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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Korte T, Ludwig K, Krumbiegel M, Zirwer D, Damaschun G, Herrmann A. Transient changes of the conformation of hemagglutinin of influenza virus at low pH detected by time-resolved circular dichroism spectroscopy. J Biol Chem 1997; 272:9764-70. [PMID: 9092509 DOI: 10.1074/jbc.272.15.9764] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Membrane fusion of influenza virus is mediated by a conformational change of the viral membrane protein hemagglutinin (HA) triggered by low pH. By near UV CD spectroscopy, which is sensitive to the arrangement and mobility of aromatic amino acids in proteins, we have monitored continuously with a time resolution of 5 s the kinetics of structural alterations of the ectodomain of HA isolated from different influenza virus strains (H1 (A/PR 8/34), H2 (A/Japan), and H3 (X31)). To establish a functional correlation to structural alterations of the HA ectodomain reflected by the CD, we have measured the kinetics of the virus-erythrocyte fusion and of the inactivation of fusion by low pH preincubation of viruses. At acidic pH we found a multiphasic behavior of the CD signal recorded at 283 nm. Upon lowering the pH we detected first an increase of the CD amplitude, which is associated with the formation of a fusion-competent state of HA. The initial increase was followed by a continuous decline of CD amplitude, which can be ascribed to a transformation into a fusion-inactivated conformation that is in its early phase reversible as found for A/Japan. The half-time of the different phases of the CD signal depended on the virus strain, the temperature, and the acidic pH. The results support recent hypotheses that the fusion-competent conformation is an intermediate of the fusion-inactivated structure of HA.
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Affiliation(s)
- T Korte
- Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, Institut für Biologie/Biophysik, Invalidenstr. 43, D-10115 Berlin, Germany
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45
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Ramalho-Santos J, Lima MC, Nir S. Partial fusion activity of influenza virus toward liposomes and erythrocyte ghosts is distinct from viral inactivation. J Biol Chem 1996; 271:23902-6. [PMID: 8798621 DOI: 10.1074/jbc.271.39.23902] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Final extents of fusion of influenza virus (A/PR/8/34 strain) with neutral and partially acidic liposomes were monitored with (i) a fluorescence resonance energy-transfer assay in which the liposomes were labeled and (ii) by the dequenching of octadecylrhodamine, initially incorporated in the viral membrane. The latter assay was also employed in the fusion of influenza virus and Sendai virus with erythrocyte ghosts. In all cases, a phenomenon of partial fusion activity of the virus was observed, which is distinct from low pH inactivation. The unfused influenza or Sendai virions, which were separated by sucrose gradient centrifugation from liposomes or erythrocyte ghosts exhibited again partial fusion activity toward freshly added liposomes or ghosts, respectively. The conclusion is that the fraction of initially bound and unfused virions does not consist of defective particles, but rather of particles bound to the target membranes via inactive sites on the virus (or on cellular membranes), or else, partial fusion activity is a manifestation of a certain probability of production of fusion inactive sites by irreversible association of viral glycoproteins or peptides in the target membrane.
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Affiliation(s)
- J Ramalho-Santos
- Center for Neurosciences of Coimbra, University of Coimbra, 3000 Coimbra, Portugal
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Günther-Ausborn S, Praetor A, Stegmann T. Inhibition of influenza-induced membrane fusion by lysophosphatidylcholine. J Biol Chem 1995; 270:29279-85. [PMID: 7493959 DOI: 10.1074/jbc.270.49.29279] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Lysolipids have been reported to inhibit various membrane fusion events, and it was suggested that inhibition was due to their "inverted cone" shape, which hinders the formation of intermediate lipid structures required for fusion (Chernomordik, L. V., Vogel, S. S., Sokoloff, A., Onaran, H. O., Leikina, E. A., and Zimmerberg, J. (1993) FEBS Lett. 318, 71-76). Here, the effect of lysophosphatidylcholine (LPC) on fusion mediated by the hemagglutinin (HA) of influenza virus was investigated. Virus-liposome fusion was inhibited by LPC if the lysolipid was added to the membranes from an aqueous stock solution but not if LPC was symmetrically distributed over both leaflets of the liposomal bilayer. These findings would be consistent with an effect of LPC on lipid intermediate formation, but inhibition increased with increasing acyl chain length and thus a less pronounced inverted cone shape of the lysolipids suggesting that the mechanism of inhibition might be different. At low pH, due to the exposure of the fusion peptide of HA, followed by its insertion into the liposomal membrane, virus acquires the ability to bind to zwitterionic liposomes lacking receptors for HA. This type of binding was inhibited by LPC. Moreover, leakage of calcein from receptor-containing liposomes, induced by purified HA at low pH, was inhibited by LPC. Therefore, the inhibition of influenza-induced fusion by LPC was caused by the binding of LPC to fusion peptides, thereby preventing their interaction with the target membrane rather than an effect on intermediate lipid structures.
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Affiliation(s)
- S Günther-Ausborn
- Department of Biophysical Chemistry, Biozentrum of the University of Basel, Switzerland
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Steinhauer DA, Wharton SA, Skehel JJ, Wiley DC. Studies of the membrane fusion activities of fusion peptide mutants of influenza virus hemagglutinin. J Virol 1995; 69:6643-51. [PMID: 7474073 PMCID: PMC189573 DOI: 10.1128/jvi.69.11.6643-6651.1995] [Citation(s) in RCA: 150] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Influenza virus hemagglutinin (HA) fuses membranes at endosomal pH by a process which involves extrusion of the NH2-terminal region of HA2, the fusion peptide, from its buried location in the native trimer. We have examined the amino acid sequence requirements for a functional fusion peptide by determining the fusion capacities of site-specific mutant HAs expressed by using vaccinia virus recombinants and of synthetic peptide analogs of the mutant fusion peptides. The results indicate that for efficient fusion, alanine can to some extent substitute for the NH2-terminal glycine of the wild-type fusion peptide but that serine, histidine, leucine, isoleucine, or phenylalanine cannot. In addition, mutants containing shorter fusion peptides as a result of single amino acid deletions are inactive, as is a mutant containing an alanine instead of a glycine at HA2 residue 8. Substitution of the glycine at HA2 residue 4 with an alanine increases the pH of fusion, and valine-for-glutamate substitutions at HA2 residues 11 and 15 are without effect. We confirm previous reports on the need for specific HAo cleavage to generate functional HAs, and we show that both inappropriately cleaved HA and mutant HAs, irrespective of their fusion capacities, upon incubation at low pH undergo the structural transition required for fusion.
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Affiliation(s)
- D A Steinhauer
- Division of Virology, National Institute for Medical Research, London, United Kingdom
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Guinea R, Carrasco L. Requirement for vacuolar proton-ATPase activity during entry of influenza virus into cells. J Virol 1995; 69:2306-12. [PMID: 7884876 PMCID: PMC188901 DOI: 10.1128/jvi.69.4.2306-2312.1995] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The role that endosomal acidification plays during influenza virus entry into MDCK cells has been analyzed by using the macrolide antibiotics bafilomycin A1 and concanamycin A as selective inhibitors of vacuolar proton-ATPase (v-[H+]ATPase), the enzyme responsible for the acidification of endosomes. Bafilomycin A1 and concanamycin A, present at the low concentrations of 5 x 10(-7) and 5 x 10(-9) M, respectively, prevented the entry of influenza virus into cells when added during the first minutes of infection. Attachment of virion particles to the cell surface was not the target for the action of bafilomycin A1. N,N'-Dicyclohexylcarbodiimide, a nonspecific inhibitor of proton-ATPases, also blocked virus entry, whereas elaiophylin, an inhibitor of the plasma-proton ATPase, had no effect. The inhibitory actions of bafilomycin A1 and concanamycin A were tested in culture medium at different pHs. Both antibiotics powerfully prevented influenza virus infection when the virus was added under low-pH conditions. This inhibition was reduced if the virus was bound to cells at 4 degrees C prior to the addition of warm low-pH medium. Moreover, incubation of cells at acidic pH potently blocked influenza virus infection, even in the absence of antibiotics. These results indicate that a pH gradient, rather than low pH, is necessary for efficient entry of influenza virus into cells.
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Affiliation(s)
- R Guinea
- Centro de Biología Molecular, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Spain
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Abstract
Infection by enveloped viruses is initiated by the fusion of viral and cellular membranes. In many cases, the viral membrane proteins that mediate fusion must undergo conformational changes to become active. Influenza hemagglutinin, for example, is activated by a dramatic conformational rearrangement, triggered by the low pH of the intracellular compartment in which fusion occurs. Structural characterization of this rearrangement has led to a reconsideration of how hemagglutinin mediates membrane fusion.
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Affiliation(s)
- F M Hughson
- Department of Molecular Biology, Princeton University, New Jersey 08544, USA
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50
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Krumbiegel M, Herrmann A, Blumenthal R. Kinetics of the low pH-induced conformational changes and fusogenic activity of influenza hemagglutinin. Biophys J 1994; 67:2355-60. [PMID: 7696474 PMCID: PMC1225619 DOI: 10.1016/s0006-3495(94)80721-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The decrease of the intrinsic tryptophan fluorescence intensity of purified influenza (X31 strain) hemagglutinin (HA) was used to monitor the low pH-induced conformational change of this protein. The kinetics of the fluorescence decrease depended strongly on the pH. At pH optimal for fusion, the change in tryptophan fluorescence was fast and could be fitted to a monoexponential function. We measured a rate constant of 5.78 s-1 (t1/2 = 120 ms) at pH 4.9 using rapid stopped-flow mixing. Under suboptimal conditions (higher pH), the rate constant was decreased by an order of magnitude. In addition, a slow component appeared and the fluorescence decrease followed a sum of two exponentials. The kinetics of conformational changes were compared with those of the fusion of influenza virus with red blood cell membranes as assessed by the R18-dequenching assay. At optimal pH the HA conformational change was not rate-limiting for the fusion process. However, at sub-optimal pH, the slow transition to the fusogenic conformational of HA resulted in slower kinetics and decreased extent of fusion.
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Affiliation(s)
- M Krumbiegel
- Section of Membrane Structure and Function, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
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