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Nelli RK, Harm TA, Siepker C, Groeltz-Thrush JM, Jones B, Twu NC, Nenninger AS, Magstadt DR, Burrough ER, Piñeyro PE, Mainenti M, Carnaccini S, Plummer PJ, Bell TM. Sialic Acid Receptor Specificity in Mammary Gland of Dairy Cattle Infected with Highly Pathogenic Avian Influenza A(H5N1) Virus. Emerg Infect Dis 2024; 30:1361-1373. [PMID: 38861554 DOI: 10.3201/eid3007.240689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024] Open
Abstract
In March 2024, the US Department of Agriculture's Animal and Plant Health Inspection Service reported detection of highly pathogenic avian influenza (HPAI) A(H5N1) virus in dairy cattle in the United States for the first time. One factor that determines susceptibility to HPAI H5N1 infection is the presence of specific virus receptors on host cells; however, little is known about the distribution of the sialic acid (SA) receptors in dairy cattle, particularly in mammary glands. We compared the distribution of SA receptors in the respiratory tract and mammary gland of dairy cattle naturally infected with HPAI H5N1. The respiratory and mammary glands of HPAI H5N1-infected dairy cattle are rich in SA, particularly avian influenza virus-specific SA α2,3-gal. Mammary gland tissues co-stained with sialic acids and influenza A virus nucleoprotein showed predominant co-localization with the virus and SA α2,3-gal. HPAI H5N1 exhibited epitheliotropism within the mammary gland, and we observed rare immunolabeling within macrophages.
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2
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Kristensen C, Larsen LE, Trebbien R, Jensen HE. The avian influenza A virus receptor SA-α2,3-Gal is expressed in the porcine nasal mucosa sustaining the pig as a mixing vessel for new influenza viruses. Virus Res 2024; 340:199304. [PMID: 38142890 PMCID: PMC10793167 DOI: 10.1016/j.virusres.2023.199304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 12/15/2023] [Accepted: 12/17/2023] [Indexed: 12/26/2023]
Abstract
Influenza A viruses (IAVs) originate from wild birds but have on several occasions jumped host barriers and are now also circulating in humans and mammals. The IAV host receptors (glycans with galactose linked to a sialic acid (SA) in an α2,3 or α2,6 linkage) are crucial host factors restricting inter-species transmission. In general, avian-origin IAVs show a preference for SA-α2,3 (avian receptor), whereas IAVs isolated from humans and pigs prefer SA-α2,6 (human receptor). N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc) are the two major SAs. Neu5Ac is expressed in all species, whereas Neu5Gc is only expressed in a limited number of domestic species such as pigs and horses, but not in humans. Despite that previous studies have shown that the IAV host receptor distribution appears to be similar in pigs and humans, none of these studies have investigated the expression of Neu5Gc-α2,6 in situ in porcine tissues. Thus, the aim of this study was to elucidate the distribution of IAV host receptors expressed in the porcine respiratory tract and relate the expression to the viral tropism of diverse host-adapted IAVs. The IAV receptor (SA-α2,3 and SA-α2,6) distribution and the presence of specifically Neu5Gc-α2,6 in the porcine nasal, tracheal, and lung tissues was investigated by lectin histochemistry. Furthermore, IAV immunohistochemistry was performed on tissues from pigs experimentally infected with IAVs, either adapted to pigs or humans, to investigate the significance of the IAV host receptors and the tropism of the diverse host-adapted IAVs. We document for the first time the expression of the avian receptor on the surface of the porcine nasal mucosa and an equal expression of Neu5Ac-α2,6 and Neu5Gc-α2,6 on the surface of the tracheal epithelium and alveoli. In all IAV-infected pigs, we found a low amount of IAV-positive cells in the trachea despite a high expression of the human receptor. Cumulatively, these findings suggest that optimal IAV replication involves a complex interplay between the viruses and their host receptors and that there might be other less clearly defined host factors that determine the site of replication.
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Affiliation(s)
- Charlotte Kristensen
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark.
| | - Lars E Larsen
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Ramona Trebbien
- Department of Virus and Microbiological Special Diagnostics, Statens Serum Institut, Copenhagen S, Denmark
| | - Henrik E Jensen
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark
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3
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Spruit CM, Sweet IR, Maliepaard JCL, Bestebroer T, Lexmond P, Qiu B, Damen MJA, Fouchier RAM, Reiding KR, Snijder J, Herfst S, Boons GJ, de Vries RP. Contemporary human H3N2 influenza A viruses require a low threshold of suitable glycan receptors for efficient infection. Glycobiology 2023; 33:784-800. [PMID: 37471650 PMCID: PMC10629718 DOI: 10.1093/glycob/cwad060] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 07/03/2023] [Accepted: 07/16/2023] [Indexed: 07/22/2023] Open
Abstract
Recent human H3N2 influenza A viruses have evolved to employ elongated glycans terminating in α2,6-linked sialic acid as their receptors. These glycans are displayed in low abundancies by (humanized) Madin-Darby Canine Kidney cells, which are commonly employed to propagate influenza A virus, resulting in low or no viral propagation. Here, we examined whether the overexpression of the glycosyltransferases β-1,3-N-acetylglucosaminyltransferase and β-1,4-galactosyltransferase 1, which are responsible for the elongation of poly-N-acetyllactosamines (LacNAcs), would result in improved A/H3N2 propagation. Stable overexpression of β-1,3-N-acetylglucosaminyltransferase and β-1,4-galactosyltransferase 1 in Madin-Darby Canine Kidney and "humanized" Madin-Darby Canine Kidney cells was achieved by lentiviral integration and subsequent antibiotic selection and confirmed by qPCR and protein mass spectrometry experiments. Flow cytometry and glycan mass spectrometry experiments using the β-1,3-N-acetylglucosaminyltransferase and/or β-1,4-galactosyltransferase 1 knock-in cells demonstrated increased binding of viral hemagglutinins and the presence of a larger number of LacNAc repeating units, especially on "humanized" Madin-Darby Canine Kidney-β-1,3-N-acetylglucosaminyltransferase cells. An increase in the number of glycan receptors did, however, not result in a greater infection efficiency of recent human H3N2 viruses. Based on these results, we propose that H3N2 influenza A viruses require a low number of suitable glycan receptors to infect cells and that an increase in the glycan receptor display above this threshold does not result in improved infection efficiency.
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Affiliation(s)
- Cindy M Spruit
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584CG Utrecht, The Netherlands
| | - Igor R Sweet
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584CG Utrecht, The Netherlands
| | - Joshua C L Maliepaard
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584CH Utrecht, The Netherlands
| | - Theo Bestebroer
- Department of Viroscience, Erasmus University Medical Center, Dr. Molewaterplein 50, 3015GE Rotterdam, The Netherlands
| | - Pascal Lexmond
- Department of Viroscience, Erasmus University Medical Center, Dr. Molewaterplein 50, 3015GE Rotterdam, The Netherlands
| | - Boning Qiu
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584CG Utrecht, The Netherlands
| | - Mirjam J A Damen
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584CH Utrecht, The Netherlands
| | - Ron A M Fouchier
- Department of Viroscience, Erasmus University Medical Center, Dr. Molewaterplein 50, 3015GE Rotterdam, The Netherlands
| | - Karli R Reiding
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584CH Utrecht, The Netherlands
| | - Joost Snijder
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584CH Utrecht, The Netherlands
| | - Sander Herfst
- Department of Viroscience, Erasmus University Medical Center, Dr. Molewaterplein 50, 3015GE Rotterdam, The Netherlands
| | - Geert-Jan Boons
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584CG Utrecht, The Netherlands
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Rd, Athens, GA 30602, United States
| | - Robert P de Vries
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584CG Utrecht, The Netherlands
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4
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Bustos NA, Ribbeck K, Wagner CE. The role of mucosal barriers in disease progression and transmission. Adv Drug Deliv Rev 2023; 200:115008. [PMID: 37442240 DOI: 10.1016/j.addr.2023.115008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 05/22/2023] [Accepted: 07/10/2023] [Indexed: 07/15/2023]
Abstract
Mucus is a biological hydrogel that coats and protects all non-keratinized wet epithelial surfaces. Mucins, the primary structural components of mucus, are critical components of the gel layer that protect against invading pathogens. For communicable diseases, pathogen-mucin interactions contribute to the pathogen's fate and the potential for disease progression in-host, as well as the potential for onward transmission. We begin by reviewing in-host mucus filtering mechanisms, including size filtering and interaction filtering, which regulate the permeability of mucus barriers to all molecules including pathogens. Next, we discuss the role of mucins in communicable diseases at the point of transmission (i.e. how the encapsulation of pathogens in emitted mucosal droplets externally to hosts may modulate pathogen infectivity and viability). Overall, mucosal barriers modulate both host susceptibility as well as the dynamics of population-level disease transmission. The study of mucins and their use in models and experimental systems are therefore crucial for understanding the mechanistic biophysical principles underlying disease transmission and the early stages of host infection.
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Affiliation(s)
- Nicole A Bustos
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Katharina Ribbeck
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Caroline E Wagner
- Department of Bioengineering, McGill University, Montreal, Quebec, Canada.
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5
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Ogun OJ, Soremekun OS, Thaller G, Becker D. An In Silico Functional Analysis of Non-Synonymous Single-Nucleotide Polymorphisms of Bovine CMAH Gene and Potential Implication in Pathogenesis. Pathogens 2023; 12:pathogens12040591. [PMID: 37111477 PMCID: PMC10142285 DOI: 10.3390/pathogens12040591] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 04/05/2023] [Accepted: 04/10/2023] [Indexed: 04/29/2023] Open
Abstract
The sugar molecule N-glycolylneuraminic acid (Neu5Gc) is one of the most common sialic acids discovered in mammals. Cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH) catalyses the conversion of N-acetylneuraminic acid (Neu5Ac) to Neu5Gc, and it is encoded by the CMAH gene. On the one hand, food metabolic incorporation of Neu5Gc has been linked to specific human diseases. On the other hand, Neu5Gc has been shown to be highly preferred by some pathogens linked to certain bovine diseases. We used various computational techniques to perform an in silico functional analysis of five non-synonymous single-nucleotide polymorphisms (nsSNPs) of the bovine CMAH (bCMAH) gene identified from the 1000 Bull Genomes sequence data. The c.1271C>T (P424L) nsSNP was predicted to be pathogenic based on the consensus result from different computational tools. The nsSNP was also predicted to be critical based on sequence conservation, stability, and post-translational modification site analysis. According to the molecular dynamic simulation and stability analysis, all variations promoted stability of the bCMAH protein, but mutation A210S significantly promoted CMAH stability. In conclusion, c.1271C>T (P424L) is expected to be the most harmful nsSNP among the five detected nsSNPs based on the overall studies. This research could pave the way for more research associating pathogenic nsSNPs in the bCMAH gene with diseases.
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Affiliation(s)
- Oluwamayowa Joshua Ogun
- Institute of Animal Breeding and Husbandry, University of Kiel, Olshausenstraße 40, 24098 Kiel, Germany
| | - Opeyemi S Soremekun
- The African Computational Genomics (TACG) Research Group, MRC/UVRI and LSHTM, Entebbe 5159, Uganda
- Molecular Bio-Computation and Drug Design Laboratory, School of Health Sciences, Westville Campus, University of KwaZulu-Natal, Durban 4001, South Africa
| | - Georg Thaller
- Institute of Animal Breeding and Husbandry, University of Kiel, Olshausenstraße 40, 24098 Kiel, Germany
| | - Doreen Becker
- Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
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Chien YAA, Alford BK, Wasik BR, Weichert WS, Parrish CR, Daniel S. Single Particle Analysis of H3N2 Influenza Entry Differentiates the Impact of the Sialic Acids (Neu5Ac and Neu5Gc) on Virus Binding and Membrane Fusion. J Virol 2023; 97:e0146322. [PMID: 36779754 PMCID: PMC10062150 DOI: 10.1128/jvi.01463-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 01/18/2023] [Indexed: 02/14/2023] Open
Abstract
Entry of influenza A viruses (IAVs) into host cells is initiated by binding to sialic acids (Sias), their primary host cell receptor, followed by endocytosis and membrane fusion to release the viral genome into the cytoplasm of the host cell. Host tropism is affected by these entry processes, with a primary factor being receptor specificity. Sias exist in several different chemical forms, including the hydroxylated N-glycolylneuraminic acid (Neu5Gc), which is found in many hosts; however, it has not been clear how modified Sias affect viral binding and entry. Neu5Gc is commonly found in many natural influenza hosts, including pigs and horses, but not in humans or ferrets. Here, we engineered HEK293 cells to express the hydoxylase gene (CMAH) that converts Neu5Ac to Neu5Gc, or knocked out the Sia-CMP transport gene (SLC35A1), resulting in cells that express 95% Neu5Gc or minimal level of Sias, respectively. H3N2 (X-31) showed significantly reduced infectivity in Neu5Gc-rich cells compared to wild-type HEK293 (>95% Neu5Ac). To determine the effects on binding and fusion, we generated supported lipid bilayers (SLBs) derived from the plasma membranes of these cells and carried out single particle microscopy. H3N2 (X-31) exhibited decreased binding to Neu5Gc-containing SLBs, but no significant difference in H3N2 (X-31)'s fusion kinetics to either SLB type, suggesting that reduced receptor binding does not affect subsequent membrane fusion. This finding suggests that for this virus to adapt to host cells rich in Neu5Gc, only receptor affinity changes are required without further adaptation of virus fusion machinery. IMPORTANCE Influenza A virus (IAV) infections continue to threaten human health, causing over 300,000 deaths yearly. IAV infection is initiated by the binding of influenza glycoprotein hemagglutinin (HA) to host cell sialic acids (Sias) and the subsequent viral-host membrane fusion. Generally, human IAVs preferentially bind to the Sia N-acetylneuraminic acid (Neu5Ac). Yet, other mammalian hosts, including pigs, express diverse nonhuman Sias, including N-glycolylneuraminic acid (Neu5Gc). The role of Neu5Gc in human IAV infections in those hosts is not well-understood, and the variant form may play a role in incidents of cross-species transmission and emergence of new epidemic variants. Therefore, it is important to investigate how human IAVs interact with Neu5Ac and Neu5Gc. Here, we use membrane platforms that mimic the host cell surface to examine receptor binding and membrane fusion events of human IAV H3N2. Our findings improve the understanding of viral entry mechanisms that can affect host tropism and virus evolution.
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Affiliation(s)
- Yu-An Annie Chien
- Department of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, USA
| | - Brynn K. Alford
- Department of Microbiology and Immunology, Cornell University, Ithaca, New York, USA
| | - Brian R. Wasik
- Department of Microbiology and Immunology, Cornell University, Ithaca, New York, USA
| | - Wendy S. Weichert
- Department of Microbiology and Immunology, Cornell University, Ithaca, New York, USA
| | - Colin R. Parrish
- Department of Microbiology and Immunology, Cornell University, Ithaca, New York, USA
| | - Susan Daniel
- Department of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, USA
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7
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Klenow L, Elfageih R, Gao J, Wan H, Withers SG, de Gier JW, Daniels R. Influenza virus and pneumococcal neuraminidases enhance catalysis by similar yet distinct sialic acid-binding strategies. J Biol Chem 2023; 299:102891. [PMID: 36634846 PMCID: PMC9929470 DOI: 10.1016/j.jbc.2023.102891] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 01/03/2023] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
Influenza A viruses and the bacterium Streptococcus pneumoniae (pneumococci) both express neuraminidases that catalyze release of sialic acid residues from oligosaccharides and glycoproteins. Although these respiratory pathogen neuraminidases function in a similar environment, it remains unclear if these enzymes use similar mechanisms for sialic acid cleavage. Here, we compared the enzymatic properties of neuraminidases from two influenza A subtypes (N1 and N2) and the pneumococcal strain TIGR4 (NanA, NanB, and NanC). Insect cell-produced N1 and N2 tetramers exhibited calcium-dependent activities and stabilities that varied with pH. In contrast, E. coli-produced NanA, NanB, and NanC were isolated as calcium insensitive monomers with stabilities that were more resistant to pH changes. Using a synthetic substrate (MUNANA), all neuraminidases showed similar pH optimums (pH 6-7) that were primarily defined by changes in catalytic rate rather than substrate binding affinity. Upon using a multivalent substrate (fetuin sialoglycans), much higher specific activities were observed for pneumococcal neuraminidases that contain an additional lectin domain. In virions, N1 and especially N2 also showed enhanced specific activity toward fetuin that was lost upon the addition of detergent, indicating the sialic acid-binding capacity of neighboring hemagglutinin molecules likely contributes to catalysis of natural multivalent substrates. These results demonstrate that influenza and pneumococcal neuraminidases have evolved similar yet distinct strategies to optimize their catalytic activity.
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Affiliation(s)
- Laura Klenow
- Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA
| | - Rageia Elfageih
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Jin Gao
- Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA
| | - Hongquan Wan
- Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA
| | - Stephen G. Withers
- Department of Chemistry, University of British Columbia, Vancouver, Canada
| | - Jan-Willem de Gier
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Robert Daniels
- Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA.
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8
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Zhao C, Pu J. Influence of Host Sialic Acid Receptors Structure on the Host Specificity of Influenza Viruses. Viruses 2022; 14:v14102141. [PMID: 36298694 PMCID: PMC9608321 DOI: 10.3390/v14102141] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/20/2022] [Accepted: 09/23/2022] [Indexed: 11/23/2022] Open
Abstract
Influenza viruses need to use sialic acid receptors to invade host cells, and the α-2,3 and α-2,6 sialic acids glycosidic bonds linking the terminal sialic acids are generally considered to be the most important factors influencing the cross-species transmission of the influenza viruses. The development of methods to detect the binding of influenza virus HA proteins to sialic acid receptors, as well as the development of glycobiological techniques, has led to a richer understanding of the structure of the sialylated glycan in influenza virus hosts. It was found that, in addition to the sialic acid glycosidic bond, sialic acid variants, length of the sialylated glycan, Gal-GlcNAc-linked glycosidic bond within the sialylated glycan, and sulfation/fucosylation of the GlcNAc within the sialylated glycan all affect the binding properties of influenza viruses to the sialic acid receptors, thus indirectly affecting the host specificity of influenza viruses. This paper will review the sialic acid variants, internal structural differences of sialylated glycan molecules that affect the host specificity of influenza viruses, and distribution characteristics of sialic acid receptors in influenza virus hosts, in order to provide a more reliable theoretical basis for the in-depth investigation of cross-species transmission of influenza viruses and the development of new antiviral drugs.
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9
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Nemanichvili N, Spruit CM, Berends AJ, Gröne A, Rijks JM, Verheije MH, de Vries RP. Wild and domestic animals variably display Neu5Ac and Neu5Gc sialic acids. Glycobiology 2022; 32:791-802. [PMID: 35648131 PMCID: PMC9387512 DOI: 10.1093/glycob/cwac033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 05/20/2022] [Accepted: 05/20/2022] [Indexed: 11/17/2022] Open
Abstract
Sialic acids are used as a receptor by several viruses and variations in the linkage type or C-5 modifications affect the binding properties. A species barrier for multiple viruses is present due to α2,3- or α2,6-linked sialic acids. The C-5 position of the sialic acid can be modified to form N-acetylneuraminic acid (Neu5Ac) or N-glycolylneuraminic acid (Neu5Gc), which acts as a determinant for host susceptibility for pathogens such as influenza A virus, rotavirus, and transmissible gastroenteritis coronavirus. Neu5Gc is present in most mammals such as pigs and horses but is absent in humans, ferrets, and dogs. However, little is known about C-5 content in wildlife species or how many C-5 modified sialic acids are present on N-linked glycans or glycolipids. Using our previously developed tissue microarray system, we investigated how 2 different lectins specific for Neu5Gc can result in varying detection levels of Neu5Gc glycans. We used these lectins to map Neu5Gc content in wild Suidae, Cervidae, tigers, and European hedgehogs. We show that Neu5Gc content is highly variable among different species. Furthermore, the removal of N-linked glycans reduces the binding of both Neu5Gc lectins while retention of glycolipids by omitting methanol treatment of tissues increases lectin binding. These findings highlight the importance of using multiple Neu5Gc lectins as the rich variety in which Neu5Gc is displayed can hardly be detected by a single lectin.
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Affiliation(s)
- Nikoloz Nemanichvili
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Cindy M Spruit
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG Utrecht, The Netherlands
| | - Alinda J Berends
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Andrea Gröne
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Jolianne M Rijks
- Dutch Wildlife Health Centre, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Monique H Verheije
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Robert P de Vries
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG Utrecht, The Netherlands
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10
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Abstract
Influenza A viruses (IAV) initiate infection by binding to glycans with terminal sialic acids on the cell surface. Hosts of IAV variably express two major forms of sialic acid, N-acetylneuraminic acid (NeuAc) and N-glycolylneuraminic acid (NeuGc). NeuGc is produced in most mammals including horses and pigs, but is absent in humans, ferrets, and birds. The only known naturally occurring IAVs that exclusively bind NeuGc are extinct highly pathogenic equine H7N7 viruses. We determined the crystal structure of a representative equine H7 hemagglutinin (HA) in complex with NeuGc and observed high similarity in the receptor-binding domain with an avian H7 HA. To determine the molecular basis for NeuAc and NeuGc specificity, we performed systematic mutational analyses, based on the structural insights, on two distant avian H7 HAs and an H15 HA. We found that mutation A135E is key for binding α2,3-linked NeuGc but does not abolish NeuAc binding. Additional mutations S128T, I130V, T189A, and K193R converted the specificity from NeuAc to NeuGc. We investigated the residues at positions 128, 130, 135, 189, and 193 in a phylogenetic analysis of avian and equine H7 HAs. This revealed a clear distinction between equine and avian residues. The highest variability was observed at key position 135, of which only the equine glutamic acid led to NeuGc binding. These results demonstrate that genetically distinct H7 and H15 HAs can be switched from NeuAc to NeuGc binding and vice versa after introduction of several mutations, providing insights into the adaptation of H7 viruses to NeuGc receptors. (250 words) Importance Influenza A viruses cause millions of cases of severe illness and deaths annually. To initiate infection and replicate, the virus first needs to bind to a structure on the cell surface, like a key fitting in a lock. For influenza A viruses, these 'keys' (receptors) on the cell surface are chains of sugar molecules (glycans). The terminal sugar on these glycans is often either N-acetylneuraminic acid (NeuAc) or N-glycolylneuraminic acid (NeuGc). Most influenza A viruses bind NeuAc, but a small minority binds NeuGc. NeuGc is present in species like horses, pigs, and mice, but not in humans, ferrets, and birds. Here, we investigated the molecular determinants of NeuGc specificity and the origin of viruses that bind NeuGc.
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