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Sederdahl BK, Weinberg GA, Campbell AP, Selvarangan R, Schuster JE, Lively JY, Olson SM, Boom JA, Piedra PA, Halasa NB, Stewart L, Szilagyi PG, Balasubramani GK, Sax T, Martin JM, Hickey RW, Michaels MG, Williams JV. Influenza C virus in U.S. children with acute respiratory infection 2016-2019. J Clin Virol 2024; 174:105720. [PMID: 39142019 DOI: 10.1016/j.jcv.2024.105720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2024] [Revised: 07/13/2024] [Accepted: 08/06/2024] [Indexed: 08/16/2024]
Abstract
Influenza C virus (ICV) is an orthomyxovirus related to influenza A and B, yet due to few commercial assays, epidemiologic studies may underestimate incidence of ICV infection and disease. We describe the epidemiology and characteristics of ICV within the New Vaccine Surveillance Network (NVSN), a Centers for Disease Control and Prevention (CDC)-led network that conducts population-based surveillance for pediatric acute respiratory illness (ARI). Nasal or/combined throat swabs were collected from emergency department (ED) or inpatient ARI cases, or healthy controls, between 12/05/2016-10/31/2019 and tested by molecular assays for ICV and other respiratory viruses. Parent surveys and chart review were used to analyze demographic and clinical characteristics of ICV+ children. Among 19,321 children tested for ICV, 115/17,668 (0.7 %) ARI cases and 8/1653 (0.5 %) healthy controls tested ICV+. Median age of ICV+ patients was 18 months and 88 (71.5 %) were ≤36 months. Among ICV+ ARI patients, 40 % (46/115) were enrolled in the ED, 60 % (69/115) were inpatients, with 15 admitted to intensive care. Most ICV+ ARI patients had fever (67.8 %), cough (94.8 %), or wheezing (60.9 %). Most (60.9 %) ARI cases had ≥1 co-detected viruses including rhinovirus, RSV, and adenovirus. In summary, ICV detection was rarely associated with ARI in children, and most ICV+ patients were ≤3 years old with co-detected respiratory viruses.
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Affiliation(s)
- Bethany K Sederdahl
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Geoffrey A Weinberg
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Angela P Campbell
- Coronavirus and other Respiratory Viruses Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Rangaraj Selvarangan
- Department of Pathology & Laboratory Medicine, University of Missouri Kansas City, Children's Mercy Hospital, Kansas City, MO, USA
| | - Jennifer E Schuster
- Department of Pediatrics, University of Missouri - Kansas City, Children's Mercy Hospital, Kansas City, MO, USA
| | - Joana Y Lively
- Division of Viral Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Samantha M Olson
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Julie A Boom
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA; Texas Children's Hospital, Houston, TX, USA
| | - Pedro A Piedra
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Natasha B Halasa
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Laura Stewart
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Peter G Szilagyi
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - G K Balasubramani
- Department of Epidemiology, University of Pittsburgh School of Public Health, Pittsburgh, PA, USA
| | - Theresa Sax
- Department of Epidemiology, University of Pittsburgh School of Public Health, Pittsburgh, PA, USA
| | - Judith M Martin
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Robert W Hickey
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Marian G Michaels
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - John V Williams
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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Sreenivasan CC, Sheng Z, Wang D, Li F. Host Range, Biology, and Species Specificity of Seven-Segmented Influenza Viruses-A Comparative Review on Influenza C and D. Pathogens 2021; 10:1583. [PMID: 34959538 PMCID: PMC8704295 DOI: 10.3390/pathogens10121583] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 11/26/2021] [Accepted: 11/30/2021] [Indexed: 02/06/2023] Open
Abstract
Other than genome structure, influenza C (ICV), and D (IDV) viruses with seven-segmented genomes are biologically different from the eight-segmented influenza A (IAV), and B (IBV) viruses concerning the presence of hemagglutinin-esterase fusion protein, which combines the function of hemagglutinin and neuraminidase responsible for receptor-binding, fusion, and receptor-destroying enzymatic activities, respectively. Whereas ICV with humans as primary hosts emerged nearly 74 years ago, IDV, a distant relative of ICV, was isolated in 2011, with bovines as the primary host. Despite its initial emergence in swine, IDV has turned out to be a transboundary bovine pathogen and a broader host range, similar to influenza A viruses (IAV). The receptor specificities of ICV and IDV determine the host range and the species specificity. The recent findings of the presence of the IDV genome in the human respiratory sample, and high traffic human environments indicate its public health significance. Conversely, the presence of ICV in pigs and cattle also raises the possibility of gene segment interactions/virus reassortment between ICV and IDV where these viruses co-exist. This review is a holistic approach to discuss the ecology of seven-segmented influenza viruses by focusing on what is known so far on the host range, seroepidemiology, biology, receptor, phylodynamics, species specificity, and cross-species transmission of the ICV and IDV.
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Affiliation(s)
- Chithra C. Sreenivasan
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA; (C.C.S.); (D.W.)
| | - Zizhang Sheng
- Aaron Diamond AIDS Research Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA;
| | - Dan Wang
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA; (C.C.S.); (D.W.)
| | - Feng Li
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA; (C.C.S.); (D.W.)
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Halldorsson S, Sader K, Turner J, Calder LJ, Rosenthal PB. In situ structure and organization of the influenza C virus surface glycoprotein. Nat Commun 2021; 12:1694. [PMID: 33727554 PMCID: PMC7966785 DOI: 10.1038/s41467-021-21818-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 02/11/2021] [Indexed: 11/09/2022] Open
Abstract
The lipid-enveloped influenza C virus contains a single surface glycoprotein, the haemagglutinin-esterase-fusion (HEF) protein, that mediates receptor binding, receptor destruction, and membrane fusion at the low pH of the endosome. Here we apply electron cryotomography and subtomogram averaging to describe the structural basis for hexagonal lattice formation by HEF on the viral surface. The conformation of the glycoprotein in situ is distinct from the structure of the isolated trimeric ectodomain, showing that a splaying of the membrane distal domains is required to mediate contacts that form the lattice. The splaying of these domains is also coupled to changes in the structure of the stem region which is involved in membrane fusion, thereby linking HEF's membrane fusion conformation with its assembly on the virus surface. The glycoprotein lattice can form independent of other virion components but we show a major role for the matrix layer in particle formation.
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Affiliation(s)
- Steinar Halldorsson
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Kasim Sader
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, London, United Kingdom
- Materials and Structural Analysis, Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG, Eindhoven, The Netherlands
| | - Jack Turner
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Lesley J Calder
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Peter B Rosenthal
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, London, United Kingdom.
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Sederdahl BK, Williams JV. Epidemiology and Clinical Characteristics of Influenza C Virus. Viruses 2020; 12:E89. [PMID: 31941041 PMCID: PMC7019359 DOI: 10.3390/v12010089] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 01/06/2020] [Accepted: 01/07/2020] [Indexed: 12/14/2022] Open
Abstract
Influenza C virus (ICV) is a common yet under-recognized cause of acute respiratory illness. ICV seropositivity has been found to be as high as 90% by 7-10 years of age, suggesting that most people are exposed to ICV at least once during childhood. Due to difficulty detecting ICV by cell culture, epidemiologic studies of ICV likely have underestimated the burden of ICV infection and disease. Recent development of highly sensitive RT-PCR has facilitated epidemiologic studies that provide further insights into the prevalence, seasonality, and course of ICV infection. In this review, we summarize the epidemiology and clinical characteristics of ICV.
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Affiliation(s)
- Bethany K. Sederdahl
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA;
| | - John V. Williams
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA;
- Institute for Infection, Inflammation, and Immunity in Children (i4Kids), University of Pittsburgh, Pittsburgh, PA 15224, USA
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To J, Torres J. Viroporins in the Influenza Virus. Cells 2019; 8:cells8070654. [PMID: 31261944 PMCID: PMC6679168 DOI: 10.3390/cells8070654] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 06/21/2019] [Accepted: 06/27/2019] [Indexed: 12/28/2022] Open
Abstract
Influenza is a highly contagious virus that causes seasonal epidemics and unpredictable pandemics. Four influenza virus types have been identified to date: A, B, C and D, with only A–C known to infect humans. Influenza A and B viruses are responsible for seasonal influenza epidemics in humans and are responsible for up to a billion flu infections annually. The M2 protein is present in all influenza types and belongs to the class of viroporins, i.e., small proteins that form ion channels that increase membrane permeability in virus-infected cells. In influenza A and B, AM2 and BM2 are predominantly proton channels, although they also show some permeability to monovalent cations. By contrast, M2 proteins in influenza C and D, CM2 and DM2, appear to be especially selective for chloride ions, with possibly some permeability to protons. These differences point to different biological roles for M2 in types A and B versus C and D, which is also reflected in their sequences. AM2 is by far the best characterized viroporin, where mechanistic details and rationale of its acid activation, proton selectivity, unidirectionality, and relative low conductance are beginning to be understood. The present review summarizes the biochemical and structural aspects of influenza viroporins and discusses the most relevant aspects of function, inhibition, and interaction with the host.
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Affiliation(s)
- Janet To
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Jaume Torres
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
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The Hemagglutinin-Esterase Fusion Glycoprotein Is a Primary Determinant of the Exceptional Thermal and Acid Stability of Influenza D Virus. mSphere 2017; 2:mSphere00254-17. [PMID: 28808690 PMCID: PMC5549178 DOI: 10.1128/msphere.00254-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 07/24/2017] [Indexed: 12/25/2022] Open
Abstract
Influenza D virus (IDV) utilizes cattle as a primary reservoir. Increased outbreaks in pigs and serological evidence of human infection have raised a concern about the potential of IDV adapting to humans. Here, we directly compared IDV’s stability to that of other influenza types (A, B, and C) following prolonged incubation at high temperatures or in a low-pH environment. We found that IDV is the most stable of the four types of influenza viruses. Importantly, we demonstrated that the hemagglutinin-esterase fusion (HEF) protein, which drives the fusion between viral and host cell membranes, is the primary determinant for the high thermal and acid stability of IDV. Considering that there is a link between the acid stability of the hemagglutinin protein of influenza A virus and its cross-species transmission, further investigation of the mechanism of HEF-directed viral tolerance may offer novel insights into tissue tropism and cross-species transmission of influenza viruses. Influenza D virus (IDV) is unique among four types of influenza viruses in that it utilizes cattle as a primary reservoir. The thermal and acid stability of IDV were examined and directly compared with those of influenza A virus (IAV), influenza B virus (IBV), and influenza C virus (ICV). The results of our experiments demonstrated that only IDV had a high residual infectivity (~2.5 log units of 50% tissue culture infective dose [TCID50]/ml) after a 60-min exposure to 53°C in solution at a neutral pH, and remarkably, IDV retained this infectivity even after exposure to 53°C for 120 min. Furthermore, the data showed that IDV was extremely resistant to inactivation by low pH. After being treated at pH 3.0 for 30 min, IDV lost only approximately 20% of its original infectiousness, while all other types of influenza viruses were completely inactivated. Finally, replacement of the hemagglutinin (HA) and neuraminidase (NA) proteins of a temperature- and acid-sensitive IAV with the hemagglutinin-esterase fusion (HEF) protein of a stable IDV through a reverse genetic system largely rendered the recombinant IAVs resistant to high-temperature and low-pH treatments. Together, these results indicated that the HEF glycoprotein is a primary determinant of the exceptional temperature and acid tolerance of IDV. Further investigation into the viral entry and fusion mechanism mediated by the intrinsically stable HEF protein of IDV may offer novel insights into how the fusion machinery of influenza viruses evolve to achieve acid and thermal stability, which as a result promotes the potential to transmit across mammal species. IMPORTANCE Influenza D virus (IDV) utilizes cattle as a primary reservoir. Increased outbreaks in pigs and serological evidence of human infection have raised a concern about the potential of IDV adapting to humans. Here, we directly compared IDV’s stability to that of other influenza types (A, B, and C) following prolonged incubation at high temperatures or in a low-pH environment. We found that IDV is the most stable of the four types of influenza viruses. Importantly, we demonstrated that the hemagglutinin-esterase fusion (HEF) protein, which drives the fusion between viral and host cell membranes, is the primary determinant for the high thermal and acid stability of IDV. Considering that there is a link between the acid stability of the hemagglutinin protein of influenza A virus and its cross-species transmission, further investigation of the mechanism of HEF-directed viral tolerance may offer novel insights into tissue tropism and cross-species transmission of influenza viruses.
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Furuse Y, Matsuzaki Y, Nishimura H, Oshitani H. Analyses of Evolutionary Characteristics of the Hemagglutinin-Esterase Gene of Influenza C Virus during a Period of 68 Years Reveals Evolutionary Patterns Different from Influenza A and B Viruses. Viruses 2016; 8:E321. [PMID: 27898037 PMCID: PMC5192382 DOI: 10.3390/v8120321] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Revised: 11/08/2016] [Accepted: 11/21/2016] [Indexed: 12/13/2022] Open
Abstract
Infections with the influenza C virus causing respiratory symptoms are common, particularly among children. Since isolation and detection of the virus are rarely performed, compared with influenza A and B viruses, the small number of available sequences of the virus makes it difficult to analyze its evolutionary dynamics. Recently, we reported the full genome sequence of 102 strains of the virus. Here, we exploited the data to elucidate the evolutionary characteristics and phylodynamics of the virus compared with influenza A and B viruses. Along with our data, we obtained public sequence data of the hemagglutinin-esterase gene of the virus; the dataset consists of 218 unique sequences of the virus collected from 14 countries between 1947 and 2014. Informatics analyses revealed that (1) multiple lineages have been circulating globally; (2) there have been weak and infrequent selective bottlenecks; (3) the evolutionary rate is low because of weak positive selection and a low capability to induce mutations; and (4) there is no significant positive selection although a few mutations affecting its antigenicity have been induced. The unique evolutionary dynamics of the influenza C virus must be shaped by multiple factors, including virological, immunological, and epidemiological characteristics.
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Affiliation(s)
- Yuki Furuse
- Department of Virology, Tohoku University Graduate School of Medicine, Sendai 9808575, Japan.
| | - Yoko Matsuzaki
- Department of Infectious Diseases, Yamagata University Faculty of Medicine, Yamagata 9909585, Japan.
| | - Hidekazu Nishimura
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai 9838520, Japan.
| | - Hitoshi Oshitani
- Department of Virology, Tohoku University Graduate School of Medicine, Sendai 9808575, Japan.
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Wang M, Ludwig K, Böttcher C, Veit M. The role of stearate attachment to the hemagglutinin-esterase-fusion glycoprotein HEF of influenza C virus. Cell Microbiol 2016; 18:692-704. [PMID: 26518983 DOI: 10.1111/cmi.12541] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 10/20/2015] [Accepted: 10/27/2015] [Indexed: 12/13/2022]
Abstract
The only spike of influenza C virus, the hemagglutinin-esterase-fusion glycoprotein (HEF) combines receptor binding, receptor hydrolysis and membrane fusion activities. Like other hemagglutinating glycoproteins of influenza viruses HEF is S-acylated, but only with stearic acid at a single cysteine located at the cytosol-facing end of the transmembrane region. Previous studies established the essential role of S-acylation of hemagglutinin for replication of influenza A and B virus by affecting budding and/or membrane fusion, but the function of acylation of HEF was hitherto not investigated. Using reverse genetics we rescued a virus containing non-stearoylated HEF, which was stable during serial passage and showed no competitive fitness defect, but the growth rate of the mutant virus was reduced by one log. Deacylation of HEF does neither affect the kinetics of its plasma membrane transport nor the protein composition of virus particles. Cryo-electron microscopy showed that the shape of viral particles and the hexagonal array of spikes typical for influenza C virus were not influenced by this mutation indicating that virus budding was not disturbed. However, the extent and kinetics of haemolysis were reduced in mutant virus at 37°C, but not at 33°C, the optimal temperature for virus growth, suggesting that non-acylated HEF has a defect in membrane fusion under suboptimal conditions.
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Affiliation(s)
- Mingyang Wang
- Institute of Virology, Department of Veterinary Medicine, Free University Berlin, Berlin, Germany
| | - Kai Ludwig
- Research Center of Electron Microscopy, Department of Chemistry, Free University Berlin, Berlin, Germany
| | - Christoph Böttcher
- Research Center of Electron Microscopy, Department of Chemistry, Free University Berlin, Berlin, Germany
| | - Michael Veit
- Institute of Virology, Department of Veterinary Medicine, Free University Berlin, Berlin, Germany
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Wang M, Veit M. Hemagglutinin-esterase-fusion (HEF) protein of influenza C virus. Protein Cell 2016; 7:28-45. [PMID: 26215728 PMCID: PMC4707155 DOI: 10.1007/s13238-015-0193-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 07/06/2015] [Indexed: 01/19/2023] Open
Abstract
Influenza C virus, a member of the Orthomyxoviridae family, causes flu-like disease but typically only with mild symptoms. Humans are the main reservoir of the virus, but it also infects pigs and dogs. Very recently, influenza C-like viruses were isolated from pigs and cattle that differ from classical influenza C virus and might constitute a new influenza virus genus. Influenza C virus is unique since it contains only one spike protein, the hemagglutinin-esterase-fusion glycoprotein HEF that possesses receptor binding, receptor destroying and membrane fusion activities, thus combining the functions of Hemagglutinin (HA) and Neuraminidase (NA) of influenza A and B viruses. Here we briefly review the epidemiology and pathology of the virus and the morphology of virus particles and their genome. The main focus is on the structure of the HEF protein as well as on its co- and post-translational modification, such as N-glycosylation, disulfide bond formation, S-acylation and proteolytic cleavage into HEF1 and HEF2 subunits. Finally, we describe the functions of HEF: receptor binding, esterase activity and membrane fusion.
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Affiliation(s)
- Mingyang Wang
- Institute of Virology, Veterinary Medicine, Free University Berlin, Berlin, Germany
| | - Michael Veit
- Institute of Virology, Veterinary Medicine, Free University Berlin, Berlin, Germany.
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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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Crescenzo-Chaigne B, van der Werf S. Rescue of influenza C virus from recombinant DNA. J Virol 2007; 81:11282-9. [PMID: 17686850 PMCID: PMC2045542 DOI: 10.1128/jvi.00910-07] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2007] [Accepted: 07/30/2007] [Indexed: 01/08/2023] Open
Abstract
The rescue of influenza viruses by reverse genetics has been described only for the influenza A and B viruses. Based on a similar approach, we developed a reverse-genetics system that allows the production of influenza C viruses entirely from cloned cDNA. The complete sequences of the 3' and 5' noncoding regions of type C influenza virus C/Johannesburg/1/66 necessary for the cloning of the cDNA were determined for the seven genomic segments. Human embryonic kidney cells (293T) were transfected simultaneously with seven plasmids that direct the synthesis of each of the seven viral RNA segments of the C/JHB/1/66 virus under the control of the human RNA polymerase I promoter and with four plasmids encoding the viral nucleoprotein and the PB2, PB1, and P3 proteins of the viral polymerase complex. This strategy yielded between 10(3) and 10(4) PFU of virus per ml of supernatant at 8 to 10 days posttransfection. Additional viruses with substitutions introduced in the hemagglutinin-esterase-fusion protein were successfully produced by this method, and their growth phenotype was evaluated. This efficient system, which does not require helper virus infection, should be useful in viral mutagenesis studies and for generation of expression vectors from type C influenza virus.
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Affiliation(s)
- Bernadette Crescenzo-Chaigne
- Unité de Génétique Moléculaire des Virus Respiratoires, URA CNRS 1966, EA 302 Université Paris Diderot, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France
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Betakova T, Hay AJ. Evidence that the CM2 protein of influenza C virus can modify the pH of the exocytic pathway of transfected cells. J Gen Virol 2007; 88:2291-2296. [PMID: 17622634 DOI: 10.1099/vir.0.82785-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The 115 residue CM2 protein of influenza C virus is a structural homologue of the M2 protein of influenza A virus. Expression of the CM2 protein in Xenopus oocytes showed that it can form a voltage-activated ion channel permeable to Cl-. To investigate whether the CM2 protein has pH modulating activity comparable to that of the M2 protein, CM2 was co-expressed with a pH-sensitive haemagglutinin (HA) from influenza A virus. The results indicate that, like the M2 protein, the CM2 protein has a capacity to reduce the acidity of the exocytic pathway and reduce conversion of the pH-sensitive HA to its low pH conformation during transport to the cell surface. By contrast, the NB protein of influenza B virus has no detectable activity. Although, the pH modulating activity of the CM2 protein was substantially less than that of the M2 protein, these observations provide support for a role in virus uncoating analogous to that of M2.
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Affiliation(s)
- Tatiana Betakova
- National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
- Institute of Virology - Slovaks Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovak Republic
| | - Alan J Hay
- National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
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Abstract
Virus attachment to host cells is mediated by dedicated virion proteins, which specifically recognize one or, at most, a limited number of cell surface molecules. Receptor binding often involves protein-protein interactions, but carbohydrates may serve as receptor determinants as well. In fact, many different viruses use members of the sialic acid family either as their main receptor or as an initial attachment factor. Sialic acids (Sias) are 9-carbon negatively-charged monosaccharides commonly occurring as terminal residues of glycoconjugates. They come in a large variety and are differentially expressed in cells and tissues. By targeting specific Sia subtypes, viruses achieve host cell selectivity, but only to a certain extent. The Sia of choice might still be abundantly present on non-cell associated molecules, on non-target cells (including cells already infected) and even on virus particles themselves. This poses a hazard, as high-affinity virion binding to any of such "false'' receptors would result in loss of infectivity. Some enveloped RNA viruses deal with this problem by encoding virion-associated receptor-destroying enzymes (RDEs). These enzymes make the attachment to Sia reversible, thus providing the virus with an escape ticket. RDEs occur in two types: neuraminidases and sialate-O-acetylesterases. The latter, originally discovered in influenza C virus, are also found in certain nidoviruses, namely in group 2 coronaviruses and in toroviruses, as well as in infectious salmon anemia virus, an orthomyxovirus of teleosts. Here, the structure, function and evolution of viral sialate-O-acetylesterases is reviewed with main focus on the hemagglutinin-esterases of nidoviruses.
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Affiliation(s)
- Raoul J de Groot
- Virology Section, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands.
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Krossøy B, Devold M, Sanders L, Knappskog PM, Aspehaug V, Falk K, Nylund A, Koumans S, Endresen C, Biering E. Cloning and identification of the infectious salmon anaemia virus haemagglutinin. J Gen Virol 2001; 82:1757-1765. [PMID: 11413388 DOI: 10.1099/0022-1317-82-7-1757] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Infectious salmon anaemia virus (ISAV) is an orthomyxo-like virus that causes serious disease in Atlantic salmon (Salmo salar). Like the orthomyxoviruses, ISAV has been shown to possess haemagglutinin (HA) activity. This study presents the cloning, expression and identification of the ISAV HA gene, which was isolated from a cDNA library by immunoscreening. The HA gene contained an ISAV-specific conserved nucleotide motif in the 5' region and a 1167 bp open reading frame encoding a protein with a predicted molecular mass of 42.4 kDa. The HA gene was expressed in a baculovirus system. A monoclonal antibody (MAb) shown previously to be directed against the ISAV HA reacted with insect cells infected with recombinant baculovirus. Salmon erythrocytes also adsorbed to these cells and adsorption was inhibited by the addition of either the ISAV-specific MAb or a polyclonal rabbit serum prepared against purified virus, confirming the virus specificity of the reaction. Immunoblot analyses indicated that ISAV HA, in contrast to influenza virus HA, is not posttranslationally cleaved. Sequence comparisons of the HA gene from five Norwegian, one Scottish and one Canadian isolate revealed a highly polymorphic region that may be useful in epidemiological studies.
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Affiliation(s)
- Bjørn Krossøy
- Department of Fisheries and Marine Biology, University of Bergen, Norway2
- Intervet Norbio, Thormøhlensgate 58, N-5008 Bergen, Norway1
| | - Magnus Devold
- Department of Fisheries and Marine Biology, University of Bergen, Norway2
| | - Lisette Sanders
- Intervet International BV, Wim de Körverstraat 35, 5831 Boxmeer, The Netherlands3
| | | | | | - Knut Falk
- National Veterinary Institute, Oslo, Norway5
| | - Are Nylund
- Department of Fisheries and Marine Biology, University of Bergen, Norway2
| | - Sjo Koumans
- Intervet International BV, Wim de Körverstraat 35, 5831 Boxmeer, The Netherlands3
| | - Curt Endresen
- Department of Fisheries and Marine Biology, University of Bergen, Norway2
| | - Eirik Biering
- Intervet Norbio, Thormøhlensgate 58, N-5008 Bergen, Norway1
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15
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Pekosz A, Lamb RA. Cell surface expression of biologically active influenza C virus HEF glycoprotein expressed from cDNA. J Virol 1999; 73:8808-12. [PMID: 10482635 PMCID: PMC112902 DOI: 10.1128/jvi.73.10.8808-8812.1999] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/1999] [Accepted: 07/08/1999] [Indexed: 11/20/2022] Open
Abstract
The hemagglutinin, esterase, and fusion (HEF) glycoprotein of influenza C virus possesses receptor binding, receptor destroying, and membrane fusion activities. The HEF cDNAs from influenza C/Ann Arbor/1/50 (HEF-AA) and influenza C/Taylor/1223/47 (HEF-Tay) viruses were cloned and expressed, and transport of HEF to the cell surface was monitored by susceptibility to cleavage by exogenous trypsin, indirect immunofluorescence microscopy, and flow cytometry. Previously it has been found in studies with the C/Johannesburg/1/66 strain of influenza C virus (HEF-JHB) that transport of HEF to the cell surface is severely inhibited, and it is thought that the short cytoplasmic tail, Arg-Thr-Lys, is involved in blocking HEF cell surface expression (F. Oeffner, H.-D. Klenk, and G. Herrler, J. Gen. Virol. 80:363-369, 1999). As the cytoplasmic tail amino acid sequences of HEF-AA and HEF-Tay are identical to that of HEF-JHB, the data indicate that cell surface expression of HEF-AA and HEF-Tay is not inhibited by this amino acid sequence. Furthermore, the abundant cell surface transport of HEF-AA and HEF-Tay indicates that their cell surface expression does not require coexpression of another viral protein. The HEF-AA and HEF-Tay HEF glycoproteins bound human erythrocytes, promoted membrane fusion in a low-pH and trypsin-dependent manner, and displayed esterase activity, indicating that the HEF glycoprotein alone mediates all three known functions at the cell surface.
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Affiliation(s)
- A Pekosz
- Howard Hughes Medical Institute, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208-3500, USA
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16
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Barbosa AT, Luiz MO, Gusmão NP, Couceiro JN. Analysis of viral and cellular parameters which affect the fusion process of influenza viruses. Braz J Med Biol Res 1997; 30:1415-20. [PMID: 9686159 DOI: 10.1590/s0100-879x1997001200005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
In the present investigation we studied the fusogenic process developed by influenza A, B and C viruses on cell surfaces and different factors associated with virus and cell membrane structures. The biological activity of purified virus strains was evaluated in hemagglutination, sialidase and fusion assays. Hemolysis by influenza A, B and C viruses ranging from 77.4 to 97.2%, from 20.0 to 65.0% from 0.2 to 93.7% and from 9.0 to 76.1% was observed when human, chicken, rabbit and monkey erythrocytes, respectively, were tested at pH 5.5. At this pH, low hemolysis indexes for influenza A, B and C viruses were observed if horse erythrocytes were used as target cells for the fusion process, which could be explained by an inefficient receptor binding activity of influenza on N-glycolyl sialic acids. Differences in hemagglutinin receptor binding activity due to its specificity to N-acetyl or N-glycolyl cell surface oligosaccharides, density of these cellular receptors and level of negative charges on the cell surface may possibly explain these results, showing influence on the sialidase activity and the fusogenic process. Comparative analysis showed a lack of dependence between the sialidase and fusion activities developed by influenza B viruses. Influenza A viruses at low sialidase titers (< 2) also exhibited clearly low hemolysis at pH 5.5 (15.8%), while influenza B viruses with similarly low sialidase titers showed highly variable hemolysis indexes (0.2 to 78.0%). These results support the idea that different virus and cell-associated factors such as those presented above have a significant effect on the multifactorial fusion process.
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Affiliation(s)
- A T Barbosa
- Departamento de Virologia, Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Brasil
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17
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Reverey H, Veit M, Ponimaskin E, Schmidt MF. Differential fatty acid selection during biosynthetic S-acylation of a transmembrane protein (HEF) and other proteins in insect cells (Sf9) and in mammalian cells (CV1). J Biol Chem 1996; 271:23607-10. [PMID: 8798573 DOI: 10.1074/jbc.271.39.23607] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The transmembrane glycoprotein HEF and its acylation deficient mutant M1 were expressed in Sf9 insect cells infected with recombinant baculovirus and in CV1 mammalian cells using the vaccinia T7 system. In insect cells (Sf9), both wild type HEF and HEF(M1) are synthesized in their precursor form HEF0, which appears as a double band in SDS gels. Digestion with glycopeptidase F and endoglycosidase H reveals that the larger 84-kDa form is modified by the attachment of unprocessed carbohydrates of the high mannose type whereas the smaller 76-kDa form is non-glycosylated. As revealed by in vitro labeling experiments with palmitic acid another modification of HEF is the attachment of a long chain fatty acid to cysteine residue Cys-652 which is located at the internal border of the cytoplasmic membrane. After labeling with [3H]palmitic acid in both systems only HEF(WT) is acylated, whereas HEF(M1) is not. High performance liquid chromatography analysis of the fatty acids bound to HEF(WT) expressed in Sf9 insect cells reveals nearly 80% of palmitic acid. In contrast to this finding, the acylation pattern of HEF expressed in CV1 cells shows nearly the same amounts of stearic and palmitic acid (40%). Since the interconversion of the input [3H]palmitic acid to stearic acid is even lower in CV1 cells than in insect cells, it follows that only HEF expressed in mammalian, but not in insect cells selects for stearic acid during its biosynthetic acylation. We extended our study to acylation of endogenous proteins in Sf9 cells. In finding only palmitate linked to protein we present evidence that, in contrast to mammalian cells, insect cells (Sf9) cannot transfer stearic acid to polypeptide. This finding favors the hypothesis of enzymatic acylation over non-enzymatic mechanisms of acyl transfer to protein.
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Affiliation(s)
- H Reverey
- Institut für Immunologie und Molekularbiologie, Freie Universität Berlin, Fachbereich Veterinärmedizin, Luisenstrasse 56, 10117 Berlin, Germany
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18
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Zimmer G, Klenk HD, Herrler G. Identification of a 40-kDa cell surface sialoglycoprotein with the characteristics of a major influenza C virus receptor in a Madin-Darby canine kidney cell line. J Biol Chem 1995; 270:17815-22. [PMID: 7629082 DOI: 10.1074/jbc.270.30.17815] [Citation(s) in RCA: 51] [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
Infection of cells by influenza C virus is known to be initiated by virus attachment to cell surface glycoconjugates containing N-acetyl-9-O-acetylneuraminic acid. Using an in vitro virus binding assay, we have detected this carbohydrate on several glycoproteins of Madin-Darby canine kidney cells (type I), a polarized epithelial cell line permissive for infection with influenza C virus. Among these proteins, only one was found to be present to a significant extent on the cell surface. This protein, gp40, was characterized as an O-glycosylated (mucin-type) integral membrane protein of 40 kDa, which was predominantly localized on the apical plasma membrane of filter-grown cells. It is a major cell surface sialoglycoprotein in this cell line and was shown to be subject to constitutive and rapid endocytosis. Thus, this glycoprotein can mediate not only the binding of influenza C virus to the cell surface, but also its delivery to endosomes, where penetration occurs by membrane fusion. Other highly sialylated cell surface glycoproteins were also detected but did not mediate influenza C virus binding to a significant extent, indicating that only gp40 contains 9-O-acetylated sialic acids.
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Affiliation(s)
- G Zimmer
- Institut für Virologie, Philipps-Universität Marburg, Federal Republic of Germany
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19
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Klein A, Krishna M, Varki NM, Varki A. 9-O-acetylated sialic acids have widespread but selective expression: analysis using a chimeric dual-function probe derived from influenza C hemagglutinin-esterase. Proc Natl Acad Sci U S A 1994; 91:7782-6. [PMID: 8052660 PMCID: PMC44486 DOI: 10.1073/pnas.91.16.7782] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
While 9-O-acetylation of sialic acids has been reported in some mammalian tissues, the distribution of this modification on specific cell types and molecules is largely unknown. The influenza C virus hemagglutinin-esterase is a membrane-bound glycoprotein that binds specifically to 9-O-acetylated sialic acids (hemagglutinin activity) and then hydrolyzes the O-acetyl group (receptor-destroying activity). A recombinant soluble form of influenza C virus hemagglutinin-esterase wherein the C-terminal transmembrane and cytoplasmic domains are replaced by the Fc portion of human IgG retains both its recognition and enzymatic functions. The latter activity can selectively remove 9-O-acetyl groups from bound or free sialic acids and, under specific conditions, 7-O-acetyl groups as well. Irreversible inactivation of the esterase unmasks stable recognition activity, giving a molecule that binds specifically to 9-O-acetylated sialic acids. These probes demonstrate widespread but selective expression of 9-O-acetylated sialic acids in certain cell types of rat tissues. Patterns of polarized or gradient expression further demonstrate the regulated nature of this modification. Direct probing of blots and thin-layer plates shows selective expression of 9-O-acetylation on certain glycoproteins and glycolipids in such tissues. Thus, 9-O-acetylation is more widespread than previously thought and occurs on specific molecules and cell types.
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Affiliation(s)
- A Klein
- Glycobiology Program, Cancer Center, University of California, San Diego, La Jolla 92093
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20
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A synthetic sialic acid analogue is recognized by influenza C virus as a receptor determinant but is resistant to the receptor-destroying enzyme. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42305-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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21
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Szepanski S, Gross HJ, Brossmer R, Klenk HD, Herrler G. A single point mutation of the influenza C virus glycoprotein (HEF) changes the viral receptor-binding activity. Virology 1992; 188:85-92. [PMID: 1566586 PMCID: PMC7131248 DOI: 10.1016/0042-6822(92)90737-a] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/1991] [Accepted: 12/27/1991] [Indexed: 12/27/2022]
Abstract
From strain JHB/1/66 of influenza C virus a mutant was derived with a change in the cell tropism. The mutant was able to grow in a subline of Madin-Darby canine kidney cells (MDCK II) which is resistant to infection by the parent virus due to a lack of receptors. Inactivation of cellular receptors by either neuraminidase or acetylesterase and generation of receptors by resialylation of cells with N-acetyl-9-O-acetylneuraminic acid (Neu5,9Ac2) indicated that 9-O-acetylated sialic acid is a receptor determinant for both parent and mutant virus. However, the mutant required less Neu5,9Ac2 on the cell surface for virus attachment than the parent virus. The increased binding efficiency enabled the mutant to infect cells with a low content of 9-O-acetylated sialic acid which were resistant to the parent virus. By comparing the nucleotide sequences of the glycoprotein (HEF) genes of the parent and the mutant virus only a single point mutation could be identified on the mutant gene. This mutation at nucleotide position 872 causes an amino acid exchange from threonine to isoleucine at position 284 on the amino acid sequence. Sequence similarity with a stretch of amino acids involved in the receptor-binding pocket of the influenza A hemagglutinin suggests that the mutation site on the influenza C glycoprotein (HEF) is part of the receptor-binding site.
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Affiliation(s)
- S Szepanski
- Institut für Virologie, Philipps-Universität Marburg, Germany
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22
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Garcia-Sastre A, Villar E, Manuguerra JC, Hannoun C, Cabezas JA. Activity of influenza C virus O-acetylesterase with O-acetyl-containing compounds. Biochem J 1991; 273(Pt 2):435-41. [PMID: 1991039 PMCID: PMC1149864 DOI: 10.1042/bj2730435] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Influenza C virus (strain C/Johannesburg/1/66) was grown, harvested, purified and used as source for the enzyme O-acetylesterase (N-acyl-O-acetylneuraminate O-acetylhydrolase; EC 3.1.1.53). This activity was studied and characterized with regard to some new substrates. The pH optimum of the enzyme is around 7.6, its stability at different pH values shows a result similar to that of the pH optimum, and its activity is well maintained in the pH range from 7.0 to 8.5 (all these tests were performed with 4-nitrophenyl acetate as substrate). Remarkable differences were found in the values of both Km and Vmax, with the synthetic substrates 4-nitrophenyl acetate, 2-nitrophenyl acetate, 4-methylumbelliferyl acetate, 1-naphthyl acetate and fluorescein diacetate. The use of 4-nitrophenyl acetate, 4-methylumbelliferyl acetate or 1-naphthyl acetate as substrate seems to be convenient for routine work, but it is better to carry out the measurements in parallel with those on bovine submandibular gland mucin (the latter is a natural and commercially available substrate). It was found that 4-acetoxybenzoic acid, as well as the methyl ester of 2-acetoxybenzoic acid, but not 2-acetoxybenzoic acid itself, are cleaved by this enzyme. Triacetin, di-O-acetyladenosine, tri-O-acetyladenosine, and di-O-acetyl-N-acetyladenosine phosphate, hitherto unreported as substrates for this viral esterase, are hydrolysed at different rates by this enzyme. We conclude that the O-acetylesterase from influenza C virus has a broad specificity towards both synthetic and natural non-sialic acid-containing substrates. Zn2+, Mn2+ and Pb2+ (as their chloride salts), N-acetylneuraminic acid, 4-methyl-umbelliferone and 2-acetoxybenzoic acid (acetylsalicylic acid) did not act as inhibitors.
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Affiliation(s)
- A Garcia-Sastre
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Salamanca, Spain
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23
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Abstract
Soon after the first isolation of an influenza C virus from a patient, it became obvious that this virus differs from other myxoviruses in several aspects. Pronounced differences have been observed in the interactions between the virus and cell surfaces, suggesting that influenza C virus attaches to the receptors different from those recognized by other myxoviruses. While influenza A and B viruses agglutinate erythrocytes from many species, including humans, the spectrum of erythrocytes agglutinated by influenza C virus is much more restricted. Erythrocytes from rats, mice, and adult chickens are suitable for hemagglutination and hemadsorption tests; cells from other species, however, react not at all or only poorly with influenza C virus. Differences are also observed so far as hemagglutination inhibitors are concerned. A variety of glycoproteins have been shown to prevent influenza A and B viruses from agglutinating erythrocytes. In the case of influenza C virus, rat serum was for a long time the only known hemagglutination inhibitor. A difference in the receptors for influenza C virus and other myxo-viruses was also suggested by studies on the receptor-destroying enzyme. The ability of influenza C virus to inactivate its own receptors was reported soon after the first isolation of this virus from a patient. However, the influenza C enzyme did not affect the receptors of other myxoviruses and, conversely, the receptor-destroying enzyme of either of the latter viruses was unable to inactivate the receptors for influenza C virus on erythrocytes. While the enzyme of influenza A and B virus was characterized as a neuraminidase in the 1950s, even with refined methodology no such activity was detectable with influenza C virus. It is now known that both the receptor-binding and receptor-destroying activities, as well as the fusion activity of influenza C virus are mediated by the only glycoprotein present on the surface of the virus particle. The structure and functions of this protein, which is designated as HEF, are reviewed in this chapter.
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Affiliation(s)
- G Herrler
- Institut für Virologie, Philipps-Universität Marburg, Germany
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24
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Veit M, Herrler G, Schmidt MF, Rott R, Klenk HD. The hemagglutinating glycoproteins of influenza B and C viruses are acylated with different fatty acids. Virology 1990; 177:807-11. [PMID: 2371783 DOI: 10.1016/0042-6822(90)90554-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We present evidence that the hemagglutinin (HA) of influenza B virus and the glycoprotein of influenza C virus (HEF) are acylated. The fatty acid linkage is sensitive to treatment with hydroxylamine and mercaptoethanol, which points to a labile thioester-type linkage. The HA of influenza B virus contains mainly palmitic acid, whereas the HEF glycoprotein of influenza C virus is acylated with stearic acid which has not been observed before as the prevailing fatty acid in viral or cellular acyl proteins.
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Affiliation(s)
- M Veit
- Institut für Virologie, Philipps-Universität Marburg, Federal Republic of Germany
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25
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Abstract
Animal viruses modify membrane permeability during lytic infection. There is a co-entry of macromolecules and virion particules during virus penetration and a drastic change in transport and membrane permeability at the late stages of the lytic cycle. Both events are of importance to understand different molecular aspects of viral infection, as virus entry into the cell and the interference of virus infection with cellular metabolism. Other methods of cell permeabilization of potential relevance to understand the mechanism of viral damage of the membrane are also discussed.
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Affiliation(s)
- L Carrasco
- Departamento de Microbiología, Universidad Autónoma and Consejo Superior de Investigaciones Científicas, Madrid, Spain
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26
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Vlasak R, Luytjes W, Leider J, Spaan W, Palese P. The E3 protein of bovine coronavirus is a receptor-destroying enzyme with acetylesterase activity. J Virol 1988; 62:4686-90. [PMID: 3184275 PMCID: PMC253582 DOI: 10.1128/jvi.62.12.4686-4690.1988] [Citation(s) in RCA: 125] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In addition to members of the Orthomyxoviridae and Paramyxoviridae, several coronaviruses have been shown to possess receptor-destroying activities. Purified bovine coronavirus (BCV) preparations have an esterase activity which inactivates O-acetylsialic acid-containing receptors on erythrocytes. Diisopropyl fluorophosphate (DFP) completely inhibits this receptor-destroying activity of BCV, suggesting that the viral enzyme is a serine esterase. Treatment of purified BCV with [3H]DFP and subsequent sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the proteins revealed that the E3 protein was specifically phosphorylated. This finding suggests that the esterase/receptor-destroying activity of BCV is associated with the E3 protein. Furthermore, treatment of BCV with DFP dramatically reduced its infectivity in a plaque assay. It is assumed that the esterase activity of BCV is required in an early step of virus replication, possibly during virus entry or uncoating.
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Affiliation(s)
- R Vlasak
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029-6574
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27
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Yamashita M, Krystal M, Palese P. Evidence that the matrix protein of influenza C virus is coded for by a spliced mRNA. J Virol 1988; 62:3348-55. [PMID: 3404579 PMCID: PMC253457 DOI: 10.1128/jvi.62.9.3348-3355.1988] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In contrast to influenza A and B viruses, which encode their matrix (M) proteins via an unspliced mRNA, the influenza C virus M protein appears to be coded for by a spliced mRNA from RNA segment 6. Although an open reading frame in RNA segment 6 of influenza C/JJ/50 virus could potentially code for a protein of 374 amino acids, a splicing event results in an mRNA coding for a 242-amino-acid M protein. The message for this protein represents the major M gene-specific mRNA species in C virus-infected cells. Despite the difference in coding strategies, there are sequence homologies among the M proteins of influenza A, B, and C viruses which confirm the evolutionary relationship of the three influenza virus types.
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Affiliation(s)
- M Yamashita
- Department of Microbiology, Mount Sinai School of Medicine, City University of New York, New York 10029
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28
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Herrler G, Multhaup G, Beyreuther K, Klenk HD. Serine 71 of the glycoprotein HEF is located at the active site of the acetylesterase of influenza C virus. Arch Virol 1988; 102:269-74. [PMID: 3144264 DOI: 10.1007/bf01310831] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The acetylesterase of influenza C virus has been reported recently to be inhibited by diisopropylfluorophosphate (DFP) [Muchmore EA, Varki A (1987) Science 236: 1293-1295]. As this inhibitor is known to bind covalently to the serine in the active site of serine esterases, we attempted to determine the serine in the active site of the influenza C acetylesterase. Incubation of purified influenza C virus with 3H-DFP resulted in the selective labelling of the influenza C glycoprotein HEF. The labelled glycoprotein was isolated from a SDS-polyacrylamide gel. Following reduction and carboxymethylation, tryptic peptides of HEF were prepared and analyzed by reversed phase HPLC. The peptide containing the 3H-DFP was subjected to sequence analysis. The amino acids determined from the NH2-terminus were used to locate the peptide on the HEF polypeptide. Radiosequencing revealed that 3H-DFP is attached to amino acid 17 of the tryptic peptide. These results indicate that serine 71 is the active-site serine of the acetylesterase of influenza C virus.
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Affiliation(s)
- G Herrler
- Institut für Virologie, Philipps-Universität Marburg, Federal Republic of Germany
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29
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Vlasak R, Krystal M, Nacht M, Palese P. The influenza C virus glycoprotein (HE) exhibits receptor-binding (hemagglutinin) and receptor-destroying (esterase) activities. Virology 1987; 160:419-25. [PMID: 3660588 DOI: 10.1016/0042-6822(87)90013-4] [Citation(s) in RCA: 101] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A cDNA copy of RNA segment 4 of influenza C/Cal/78 virus was cloned into an SV40 vector and expressed in CV-1 cells. The gene product expressed from the SV40 recombinant virus was immunoprecipitated by monoclonal antibodies directed against the influenza C virus glycoprotein. Cells infected with the recombinant virus also exhibited C virus-specific hemagglutinin and O-acetylesterase activity. This suggests that the same C virus protein is associated with receptor-binding as well as receptor-destroying activity. The latter viral activity was measured using as substrates bovine submaxillary mucin or a low molecular weight compound p-nitrophenylacetate. In analogy to the parainfluenza virus HN protein, the influenza C virus glycoprotein was termed HE, because it possesses hemagglutinin and esterase (receptor-destroying) activity.
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Affiliation(s)
- R Vlasak
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029
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30
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Muchmore EA, Varki A. Selective inactivation of influenza C esterase: a probe for detecting 9-O-acetylated sialic acids. Science 1987; 236:1293-5. [PMID: 3589663 DOI: 10.1126/science.3589663] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The influenza C virus (INF-C) hemagglutinin recognizes 9-O-acetyl-N-acetylneuraminic acid. The same protein contains the receptor-destroying enzyme (RDE), which is a 9-O-acetyl-esterase. The RDE was inactivated by the serine esterase inhibitor di-isopropyl fluorophosphate (DFP). [3H]DFP-labeling localized the active site to the heavy chain of the glycoprotein. DFP did not alter the hemagglutination or fusion properties of the protein, but markedly decreased infectivity of the virus, demonstrating that the RDE is important for primary infection. Finally, DFP-treated INF-C bound specifically and irreversibly to cells expressing 9-O-acetylated sialic acids. This provides a probe for a molecule that was hitherto very difficult to study.
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31
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Watanabe Y, Tashiro M, Kitame F, Homma M. Enhancement of influenza virus hemolysis by physical and serological treatments. Microbiol Immunol 1985; 29:825-37. [PMID: 2999567 DOI: 10.1111/j.1348-0421.1985.tb00885.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The mode of hemolysis by influenza A virus was compared with that of Sendai virus. The WSN strain of influenza virus grown in either eggs or MDCK cells expressed hardly any hemolytic activity by itself. Treatment of the MDCK cell-grown WSN virus with sonication or freezing and thawing moderately enhanced the hemolytic activity, but the maximum level attainable was considerably lower than that of Sendai virus. A high level of hemolytic activity comparable to that of Sendai virus was obtained only after treatment of the virus with antibody and complement. An electron microscopic study revealed that non- or low-hemolytic WSN virions were not permeable to uranyl acetate stain in contrast with the hemolytic virions obtained after treatment with antibody and complement, indicating that the hemolytic virions had sustained some injury to their envelopes. These phenomena were comparable to those found with Sendai virus, showing that damage to the envelope is also responsible for the hemolysis of influenza virus. The influenza viruses, however, remained spherical after every treatment and the stain did not penetrate into the core of the virion. These observations suggest that the envelope of influenza virus is more rigid than that of Sendai virus but that the hemolytic process of influenza virus is nevertheless mediated through envelope-membrane fusion as in the case of Sendai virus.
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Abstract
The amino acid sequence of the influenza C/JHB/1/66 glycoprotein was predicted from sequence analysis of cloned DNA. The glycoprotein exhibited several similarities to the haemagglutinin (HA) glycoproteins of influenza A and B viruses, although its overall homology to these glycoproteins was low. A comparison between the sequences of C/JHB/1/66 and C/Cal/78 strains revealed 96% homology. The nucleotide and amino acid changes appeared to be non-random, with a high proportion occurring between amino acid positions 182-212. A comparison between the JHB/1/66 glycoprotein and the influenza A/X31 HA sequence suggested that this region may be structurally analogous to the 'A' antigenic site of the HA glycoprotein.
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Doxsey SJ, Sambrook J, Helenius A, White J. An efficient method for introducing macromolecules into living cells. J Cell Biol 1985; 101:19-27. [PMID: 2989298 PMCID: PMC2113646 DOI: 10.1083/jcb.101.1.19] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The hemagglutinin (HA) of influenza virus was used to obtain efficient and rapid bulk delivery of antibodies and horseradish peroxidase (HRP) into the cytoplasm of living tissue culture cells. By exploiting HA's efficient cell surface expression, its high affinity for erythrocytes, and its acid-dependent membrane fusion activity, a novel delivery method was developed. The approach is unique in that the mediator of both binding and fusion (the HA) is present on the surfaces of the target cells. A recently developed 3T3 cell line which permanently expresses HA, Madin-Darby canine kidney cells infected with influenza virus, and CV-1 cells infected with a simian virus 40 vector carrying the HA gene were used as recipient cells. Protein-loaded erythrocytes were bound to the HA on the cell surface and a brief drop in pH to 5.0 was used to trigger HA's fusion activity and hence delivery. About 3 to 8 erythrocytes fused per 3T3 and CV-1 cell, respectively, and 75-95% of the cells received IgG or HRP. Quantitative analysis showed that 1.8 X 10(8) molecules of HRP and 1.4 X 10(7) IgG molecules were delivered per CV-1 cell and 6.2 X 10(7) HRP molecules per 3T3 cell. Cell viability, as judged by methionine incorporation into protein and cell growth and division, was not impaired. Electron and fluorescence microscopy showed that the fused erythrocyte membranes remained as discrete domains in the cell's plasma membrane. The method is simple, reliable, and nonlytic. The ability to simultaneously and rapidly deliver impermeable substances into large numbers of cells will permit biochemical analysis of the fate and effect of a variety of delivered molecules.
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Sugawara K, Kitame F, Homma M, Nakamura K. An assay for the receptor-destroying activity of influenza C virus. Microbiol Immunol 1985; 29:1207-17. [PMID: 3831720 DOI: 10.1111/j.1348-0421.1985.tb00910.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We have developed a convenient method for assaying the receptor-destroying enzyme (RDE) activity of influenza C virus. This method measures the ability of the RDE to destroy the hemagglutination-inhibition activity of a potent inhibitor present in rat serum. Some physico-chemical properties of the RDE of influenza C virus were investigated by using this method. The temperature optimum for maximal activity of this enzyme was found to be 45 C to 53 C. There was little difference in thermostability between the RDE and hemagglutinating activities of influenza C virus. When influenza C virions were treated with various concentrations of trypsin, the RDE activity decreased in parallel with the decrease in the amount of residual gp88 glycoprotein, suggesting association of RDE with this glycoprotein.
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Hewat EA, Cusack S, Ruigrok RW, Verwey C. Low resolution structure of the influenza C glycoprotein determined by electron microscopy. J Mol Biol 1984; 175:175-93. [PMID: 6726808 DOI: 10.1016/0022-2836(84)90473-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The influenza C glycoprotein is clearly seen to be a trimer in specimens prepared with uranyl stains. Three-dimensional reconstructions from naturally occurring hexagonal arrays show that at low resolution (approximately 30 A) the influenza C glycoprotein exhibits similar features to the haemagglutinin glycoprotein of influenza A. Both have a triangular stalk near the membrane. Further from the membrane, the stalk becomes broader and the monomers more separated, leaving an open centre. The molecule narrows at the top. The regions of greatest contact between adjacent trimers in the arrays are situated nearer the distal end of the molecule. These contact zones can be related to equivalent zones on the influenza A haemagglutinin. Differences between the structure of the influenza A haemagglutinin glycoprotein determined by X-ray analysis and reconstructions of the influenza C glycoprotein are greatest at either end of the molecule, where the reconstructions are least reliable. Ordered glycoprotein arrays have not been observed on influenza C virions incubated at low pH. The staining patterns of glycoproteins on intact virions are essentially determined by the pH at which the virus is incubated, and the stain type, but not the pH of the stain.
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Nakada S, Creager RS, Krystal M, Aaronson RP, Palese P. Influenza C virus hemagglutinin: comparison with influenza A and B virus hemagglutinins. J Virol 1984; 50:118-24. [PMID: 6699942 PMCID: PMC255590 DOI: 10.1128/jvi.50.1.118-124.1984] [Citation(s) in RCA: 73] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The complete nucleotide sequence of the influenza C/California/78 virus RNA 4 was obtained by using cloned cDNA derived from the RNA segment. This gene is 2,071 nucleotides long and can code for a polypeptide of 654 amino acids. Although there are no convincing sequence homologies between RNA 4 and the hemagglutinin genes of influenza A and B viruses, we suggest, on the basis of structural features, that RNA 4 of the influenza C virus codes for the hemagglutinin. The structural features which are common to the hemagglutinins of influenza A, B, and C viruses include (i) a hydrophobic signal peptide, (ii) an arginine cleavage site between the hemagglutinin 1 and 2 subunits, (iii) hydrophobic regions at the amino and carboxyl termini of the hemagglutinin 2 subunit, and (iv) several conserved cysteine residues. Additional evidence that RNA 4 of influenza C virus codes for the hemagglutinin is that the tripeptide Ile-Phe-Gly, known to be present at the amino terminus of the hemagglutinin 2 subunit of influenza C virus, is encoded by RNA 4 at a point immediately adjacent to the presumptive arginine cleavage site. The lack of primary sequence homology between the influenza C virus hemagglutinin and the influenza A or B virus hemagglutinins, which all have similar functions, might be attributed to convergent rather than divergent evolution. However, the structural similarities among the influenza A, B, and C virus hemagglutinins strongly suggest that the three hemagglutinin genes have diverged from a common precursor.
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van Meer G, Simons K. An efficient method for introducing defined lipids into the plasma membrane of mammalian cells. J Biophys Biochem Cytol 1983; 97:1365-74. [PMID: 6313696 PMCID: PMC2112692 DOI: 10.1083/jcb.97.5.1365] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
An efficient method has been devised to introduce lipid molecules into the plasma membrane of mammalian cells. This method has been applied to fuse lipid vesicles with the apical plasma membrane of Madin-Darby canine kidney cells. The cells were infected with fowl plague or influenza N virus. 4 h after infection, the hemagglutinin (HA) spike glycoprotein of the virus was present in the apical plasma membrane of the cells. Lipid vesicles containing egg phosphatidylcholine, cholesterol, and an HA receptor (ganglioside) were then bound to the cells at 0 degrees C. More than 85% of the vesicles were released by external neuraminidase at 0 degrees C or by simply warming the cells to 37 degrees C for 10 s, probably because of the action of the viral neuraminidase at the cell surface. However, when the cells were warmed to 37 degrees C in a pH 5.3 medium for 30 s, 50% of the bound vesicles could no longer be released by external neuraminidase. This only occurred when the HA protein had been cleaved into its HA1 and HA2 subunits. When we used influenza N virus, whose HA is not cleaved in Madin-Darby canine kidney cells, cleavage with external trypsin was required. The fact that the HA protein has fusogenic properties at low pH only in its cleaved form suggests that fusion of the vesicles with the plasma membrane had taken place. Further confirmation for fusion was obtained using an assay based on the decrease of energy transfer between two fluorescent phospholipids in a vesicle upon fusion of the vesicle with the plasma membrane (Struck, D. K., D. Hoekstra, and R. E. Pagano. 1981. Biochemistry, 20:4093-4099).
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Abstract
In a living cell membrane-bound compartments are continuously either separated or united through fusion reactions, and literally thousands of such reactions take place every minute. The formation of membrane vesicles from pre-existing membranes, and their fusion with specific acceptor membranes, constitute a prerequisite for the transport of most impermeant molecules and macromolecules into the cell by endocytosis, out of the cell by exocytosis, and between the cellular organelles (Palade, 1975; Silverstein, 1978; Evered & Collins, 1982). Less frequent, but equally crucial, are fusion events in fertilization, cell division, polykaryon formation, enucleation, etc. (for reviews see Poste & Nicholson, 1978). Although a great deal is known about the properties and consequences of individual forms of membrane fusion in cellular systems, and about fusion in artificial lipid membranes, the molecular basis for the reactions remain largely unclear.
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Abstract
Human erythrocytes pretreated with fungal semialkali protease or trypsin became susceptible to hemagglutination by vesicular stomatitis virus (VSV) and rabies virus. Both viruses exhibited extensive hemolytic and fusion activities against erythrocytes pretreated with these enzymes. The hemolysis and fusion were pH dependent and the activities were most apparent at pH 5.0 and decreased with increase in pH. However, VSV still exhibited slight hemolytic activity at neutral pH. Hemolysis was also dependent on the dose of virus and was inhibited by treatment of the viruses with antiviral antibody. Results of sodium dodecyl sulfate polyacrylamide gel electrophoresis of erythrocyte membranes suggested that most of the carbohydrates were removed from the membrane proteins by the treatment with proteolytic enzymes.
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