scholarly journals Neuraminidase Inhibition Contributes to Influenza A Virus Neutralization by Anti-Hemagglutinin Stem Antibodies

2018 ◽  
Author(s):  
Ivan Kosik ◽  
Davide Angeletti ◽  
James S. Gibbs ◽  
Matthew Angel ◽  
Kazuyo Takeda ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Influenza A ◽  
Cell Activation ◽  
Immune Cell ◽  
Broadly Neutralizing Antibodies ◽  
Neutralization Activity ◽  
Immune Cell Activation ◽  
Influenza Virus Hemagglutinin ◽  
Infected Cells

SummaryBroadly neutralizing antibodies (Abs) that bind the influenza virus hemagglutinin (HA) stem may enable universal influenza vaccination. Here, we show that anti-stem Abs sterically inhibit viral neuraminidase activity against large substrates, with activity inversely proportional to the length of the fibrous NA stalk that supports the enzymatic domain. By modulating NA stalk length in recombinant IAVs, we show that anti-stem Abs inhibit virus release from infected cells by blocking NA, accounting for theirin vitroneutralization activity. NA inhibition contributes to anti-stem Ab protection in influenza infected mice, likely due at least in part to NA-mediated inhibition of FcγR dependent activation of innate immune cells by antibody bound to virions. FDA approved NA inhibitors enhance anti-stem based Fcγdependent immune cell activation, raising the possibility of therapeutic synergy between NA inhibitors and anti-stem mAb treatment in humans.

scholarly journals Neuraminidase inhibition contributes to influenza A virus neutralization by anti-hemagglutinin stem antibodies

2019 ◽  
Vol 216 (2) ◽  
pp. 304-316 ◽  
Author(s):  
Ivan Kosik ◽  
Davide Angeletti ◽  
James S. Gibbs ◽  
Matthew Angel ◽  
Kazuyo Takeda ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Influenza A ◽  
Cell Activation ◽  
Immune Cell ◽  
Broadly Neutralizing Antibodies ◽  
Neutralization Activity ◽  
Immune Cell Activation ◽  
Influenza Virus Hemagglutinin ◽  
Infected Cells

Broadly neutralizing antibodies (Abs) that bind the influenza virus hemagglutinin (HA) stem may enable universal influenza vaccination. Here, we show that anti-stem Abs sterically inhibit viral neuraminidase (NA) activity against large substrates, with activity inversely proportional to the length of the fibrous NA stalk that supports the enzymatic domain. By modulating NA stalk length in recombinant IAVs, we show that anti-stem Abs inhibit virus release from infected cells by blocking NA, accounting for their in vitro neutralization activity. NA inhibition contributes to anti-stem Ab protection in influenza-infected mice, likely due at least in part to NA-mediated inhibition of FcγR-dependent activation of innate immune cells by Ab bound to virions. Food and Drug Administration–approved NA inhibitors enhance anti-stem–based Fc-dependent immune cell activation, raising the possibility of therapeutic synergy between NA inhibitors and anti-stem mAb treatment in humans.

scholarly journals Mutations in Influenza A Virus Neuraminidase and Hemagglutinin Confer Resistance against a Broadly Neutralizing Hemagglutinin Stem Antibody

2018 ◽  
Vol 93 (2) ◽  
Author(s):  
Kristina L. Prachanronarong ◽  
Aneth S. Canale ◽  
Ping Liu ◽  
Mohan Somasundaran ◽  
Shurong Hou ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A Virus ◽  
Neutralizing Antibodies ◽  
Influenza A ◽  
Cultured Cells ◽  
Whole Genome ◽  
Resistance Mutations ◽  
Broadly Neutralizing Antibodies ◽  
Influenza Virus Hemagglutinin

ABSTRACTInfluenza A virus (IAV), a major cause of human morbidity and mortality, continuously evolves in response to selective pressures. Stem-directed, broadly neutralizing antibodies (sBnAbs) targeting the influenza virus hemagglutinin (HA) are a promising therapeutic strategy, but neutralization escape mutants can develop. We used an integrated approach combining viral passaging, deep sequencing, and protein structural analyses to define escape mutations and mechanisms of neutralization escapein vitrofor the F10 sBnAb. IAV was propagated with escalating concentrations of F10 over serial passages in cultured cells to select for escape mutations. Viral sequence analysis revealed three mutations in HA and one in neuraminidase (NA). Introduction of these specific mutations into IAV through reverse genetics confirmed their roles in resistance to F10. Structural analyses revealed that the selected HA mutations (S123G, N460S, and N203V) are away from the F10 epitope but may indirectly impact influenza virus receptor binding, endosomal fusion, or budding. The NA mutation E329K, which was previously identified to be associated with antibody escape, affects the active site of NA, highlighting the importance of the balance between HA and NA function for viral survival. Thus, whole-genome population sequencing enables the identification of viral resistance mutations responding to antibody-induced selective pressure.IMPORTANCEInfluenza A virus is a public health threat for which currently available vaccines are not always effective. Broadly neutralizing antibodies that bind to the highly conserved stem region of the influenza virus hemagglutinin (HA) can neutralize many influenza virus strains. To understand how influenza virus can become resistant or escape such antibodies, we propagated influenza A virusin vitrowith escalating concentrations of antibody and analyzed viral populations by whole-genome sequencing. We identified HA mutations near and distal to the antibody binding epitope that conferred resistance to antibody neutralization. Additionally, we identified a neuraminidase (NA) mutation that allowed the virus to grow in the presence of high concentrations of the antibody. Virus carrying dual mutations in HA and NA also grew under high antibody concentrations. We show that NA mutations mediate the escape of neutralization by antibodies against HA, highlighting the importance of a balance between HA and NA for optimal virus function.

Abstract P139: The Relationship Between Tissue Sodium Storage, Immune Cell Activation And Salt-sensitive Hypertension

Hypertension ◽  
2020 ◽  
Vol 76 (Suppl_1) ◽  
Author(s):  
Melis Sahinoz ◽  
Fernando Elijovich ◽  
Cheryl L Laffer ◽  
Ashley Pitzer ◽  
Thomas G Stewart ◽  
...  
Keyword(s):  
Cell Activation ◽  
Immune Cell ◽  
Small Sample Size ◽  
Salt Sensitivity ◽  
Small Sample ◽  
Sensitivity Index ◽  
Salt Loading ◽  
Immune Cell Activation ◽  
Salt Depletion

Introduction: Salt Sensitivity (SS) of blood pressure (BP) is an independent predictor of death due to cardiovascular disease, but its pathogenesis is poorly understood. Sodium (Na + ) is stored in the skin and muscle interstitium. This hyperosmolar Na + activates monocytes in vitro via oxidative stress with generation of isolevuglandin (isoLG) protein adducts that are immunogenic and activate the adaptive immune system. Methods: Five subjects with essential hypertension discontinued all anti-hypertensive therapy for two weeks before the study. SS was assessed by an inpatient protocol of salt loading (460 mmoL/24h) and salt depletion (10 mmoL/24h, plus furosemide 40 mg x 3). Muscle and skin Na + contents were measured at baseline (BA) by 23 Sodium magnetic resonance imaging ( 23 NaMRI). Urine and serum electrolytes, glomerular filtration rate and the % CD14 + monocytes containing isoLG adducts using flow cytometry were obtained at BA, after salt-loading (HI) and after salt-depletion (LO). All continuous data are displayed as median (interquartile range). Spearman’s correlation was used to test associations. Results: Median age was 54 years (44-55), 60% of subjects were female, screening systolic BP (SBP) was 140 mmHg (134-148), diastolic BP was 88 mmHg (84-99) and BMI was 35 kg/m 2 (30-39). SBP response to salt-depletion (salt-sensitivity index, SSI) varied from -13.8 to +1.8 mmHg. %isoLG + CD14 + cells were 48 (27-65) at BA, 55 (31-56) at HI, and 70 (33-72) at LO (p=0.594, by the Kruskal-Wallis test). The correlation between SSI and delta (Δ) %isoLG LO minus HI, was 0.86, [95% confidence interval (CI), -0.07-0.99] which may suggest conclusively as we gather more data that the greater the SSI, the larger the decrease in isoLGs by salt depletion. Muscle Na + content correlated with 24h urine Na + (BA) (r=0.90, 95% CI, 0.11-0.99), however, the correlation with BP, SSI or isoLGs was inconclusive, potentially due to the small sample size. Skin Na + content correlated with baseline %CD14IsoLG + (r=0.91; 95% CI, 0.12-0.99). Conclusions: Na + intake is a component of the determinants of muscle Na + . Skin Na + is associated with increased isoLGs in monocytes, a marker of immune cell activation. Variability in ΔCD14isoLG may serve as a biomarker for SS of BP in humans.

scholarly journals Universal protection against influenza infection by a multidomain antibody to influenza hemagglutinin

Science ◽  
2018 ◽  
Vol 362 (6414) ◽  
pp. 598-602 ◽  
Author(s):  
Nick S. Laursen ◽  
Robert H. E. Friesen ◽  
Xueyong Zhu ◽  
Mandy Jongeneelen ◽  
Sven Blokland ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Neutralizing Antibodies ◽  
Influenza A ◽  
Influenza Infection ◽  
Cross Reactivity ◽  
Broadly Neutralizing Antibodies ◽  
Adeno Associated Virus ◽  
Influenza Hemagglutinin ◽  
Influenza Virus Hemagglutinin ◽  
Single Domain Antibodies

Broadly neutralizing antibodies against highly variable pathogens have stimulated the design of vaccines and therapeutics. We report the use of diverse camelid single-domain antibodies to influenza virus hemagglutinin to generate multidomain antibodies with impressive breadth and potency. Multidomain antibody MD3606 protects mice against influenza A and B infection when administered intravenously or expressed locally from a recombinant adeno-associated virus vector. Crystal and single-particle electron microscopy structures of these antibodies with hemagglutinins from influenza A and B viruses reveal binding to highly conserved epitopes. Collectively, our findings demonstrate that multidomain antibodies targeting multiple epitopes exhibit enhanced virus cross-reactivity and potency. In combination with adeno-associated virus–mediated gene delivery, they may provide an effective strategy to prevent infection with influenza virus and other highly variable pathogens.

scholarly journals Replication-Competent ΔNS1 Influenza A Viruses Expressing Reporter Genes

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 698
Author(s):  
Aitor Nogales ◽  
Michael Schotsaert ◽  
Raveen Rathnasinghe ◽  
Marta L. DeDiego ◽  
Adolfo García-Sastre ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Influenza A ◽  
Fluorescent Protein ◽  
Cultured Cells ◽  
Fluorescent Microscopy ◽  
Reporter Genes ◽  
In Vivo Studies ◽  
Structural Protein ◽  
Infected Cells

The influenza A virus (IAV) is able to infect multiple mammalian and avian species, and in humans IAV is responsible for annual seasonal epidemics and occasional pandemics of respiratory disease with significant health and economic impacts. Studying IAV involves laborious secondary methodologies to identify infected cells. Therefore, to circumvent this requirement, in recent years, multiple replication-competent infectious IAV expressing traceable reporter genes have been developed. These IAVs have been very useful for in vitro and/or in vivo studies of viral replication, identification of neutralizing antibodies or antivirals, and in studies to evaluate vaccine efficacy, among others. In this report, we describe, for the first time, the generation and characterization of two replication-competent influenza A/Puerto Rico/8/1934 H1N1 (PR8) viruses where the viral non-structural protein 1 (NS1) was substituted by the monomeric (m)Cherry fluorescent or the NanoLuc luciferase (Nluc) proteins. The ΔNS1 mCherry was able to replicate in cultured cells and in Signal Transducer and Activator of Transcription 1 (STAT1) deficient mice, although at a lower extent than a wild-type (WT) PR8 virus expressing the same mCherry fluorescent protein (WT mCherry). Notably, expression of either reporter gene (mCherry or Nluc) was detected in infected cells by fluorescent microscopy or luciferase plate readers, respectively. ΔNS1 IAV expressing reporter genes provide a novel approach to better understand the biology and pathogenesis of IAV, and represent an excellent tool to develop new therapeutic approaches against IAV infections.

scholarly journals AHCC Activation and Selection of Human Lymphocytes via Genotypic and Phenotypic Changes to an Adherent Cell Type: A Possible Novel Mechanism of T Cell Activation

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Loretta Olamigoke ◽  
Elvedina Mansoor ◽  
Vivek Mann ◽  
Ivory Ellis ◽  
Elvis Okoro ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Immune Cell ◽  
Human Lymphocytes ◽  
Gene Array ◽  
Adherent Cell ◽  
Immune Cell Activation ◽  
Wide Range

Active Hexose Correlated Compound (AHCC) is a fermented mushroom extract and immune supplement that has been used to treat a wide range of health conditions. It helps in augmentation of the natural immune response and affects immune cell activation and outcomes. The goal of this project was to study and understand the role and mechanisms of AHCC supplementation in the prevention of immunosuppression through T cell activation. The method described here involves “in vitro” culturing of lymphocytes, exposing them to different concentrations of AHCC (0 μg/mL, 50 μg/mL, 100 μg/mL, 250 μg/mL, and 500 μg/mL) at 0 hours. Interestingly, clumping and aggregation of the cells were seen between 24 and 72 hours of incubation. The cells lay down extracellular matrix, which become adherent, and phenotypical changes from small rounded lymphocytes to large macrophage-like, spindle shaped, elongated, fibroblast-like cells even beyond 360 hours were observed. These are probably translated from genotypic changes in the cells since the cells propagate for at least 3 to 6 generations (present observations). RNA isolated was subjected to gene array analysis. We hypothesize that cell adhesion is an activation and survival pathway in lymphocytes and this could be the mechanism of AHCC activation in human lymphocytes.

scholarly journals An ENU-induced splicing mutation reveals a role for Unc93b1 in early immune cell activation following influenza A H1N1 infection

2014 ◽  
Vol 15 (5) ◽  
pp. 320-332 ◽  
Author(s):  
E I Lafferty ◽  
A Flaczyk ◽  
I Angers ◽  
R Homer ◽  
E d'Hennezel ◽  
...  
Keyword(s):  
Influenza A ◽  
Cell Activation ◽  
Immune Cell ◽  
Splicing Mutation ◽  
H1n1 Infection ◽  
Immune Cell Activation ◽  
Influenza A H1n1

scholarly journals Collagens are functional, high affinity ligands for the inhibitory immune receptor LAIR-1

2006 ◽  
Vol 203 (6) ◽  
pp. 1419-1425 ◽  
Author(s):  
Robert Jan Lebbink ◽  
Talitha de Ruiter ◽  
Jelle Adelmeijer ◽  
Arjan B. Brenkman ◽  
Joop M. van Helvoort ◽  
...  
Keyword(s):  
Immune Regulation ◽  
Cell Activation ◽  
Cell Function ◽  
Immune Cell ◽  
Cell Interaction ◽  
Immune Cell Function ◽  
Affinity Ligands ◽  
Immune Cell Activation ◽  
High Affinity

Collagens are the most abundant proteins in the human body, important in maintenance of tissue structure and hemostasis. Here we report that collagens are high affinity ligands for the broadly expressed inhibitory leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1). The interaction is dependent on the conserved Gly-Pro-Hyp collagen repeats. Antibody cross-linking of LAIR-1 is known to inhibit immune cell function in vitro. We now show that collagens are functional ligands for LAIR-1 and directly inhibit immune cell activation in vitro. Thus far, all documented ligands for immune inhibitory receptors are membrane molecules, implying a regulatory role in cell–cell interaction. Our data reveal a novel mechanism of peripheral immune regulation by inhibitory immune receptors binding to extracellular matrix collagens.

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