scholarly journals Inhibition of Coxsackie B Virus Infection by Soluble Forms of Its Receptors: Binding Affinities, Altered Particle Formation, and Competition with Cellular Receptors

2005 ◽  
Vol 79 (18) ◽  
pp. 12016-12024 ◽  
Author(s):  
Ian G. Goodfellow ◽  
David J. Evans ◽  
Anna M. Blom ◽  
Dave Kerrigan ◽  
J. Scott Miners ◽  
...  
Keyword(s):  
Virus Infection ◽  
Binding Affinity ◽  
Fold Increase ◽  
Particle Formation ◽  
Viral Inhibition ◽  
Virus Binding ◽  
Surface Plasmon Resonance Analysis ◽  
Complement Regulation ◽  
Adenovirus Receptor

ABSTRACT We previously reported that soluble decay-accelerating factor (DAF) and coxsackievirus-adenovirus receptor (CAR) blocked coxsackievirus B3 (CVB3) myocarditis in mice, but only soluble CAR blocked CVB3-mediated pancreatitis. Here, we report that the in vitro mechanisms of viral inhibition by these soluble receptors also differ. Soluble DAF inhibited virus infection through the formation of reversible complexes with CVB3, while binding of soluble CAR to CVB induced the formation of altered (A) particles with a resultant irreversible loss of infectivity. A-particle formation was characterized by loss of VP4 from the virions and required incubation of CVB3-CAR complexes at 37°C. Dimeric soluble DAF (DAF-Fc) was found to be 125-fold-more effective at inhibiting CVB3 than monomeric DAF, which corresponded to a 100-fold increase in binding affinity as determined by surface plasmon resonance analysis. Soluble CAR and soluble dimeric CAR (CAR-Fc) bound to CVB3 with 5,000- and 10,000-fold-higher affinities than the equivalent forms of DAF. While DAF-Fc was 125-fold-more effective at inhibiting virus than monomeric DAF, complement regulation by DAF-Fc was decreased 4 fold. Therefore, while the virus binding was a cooperative event, complement regulation was hindered by the molecular orientation of DAF-Fc, indicating that the regions responsible for complement regulation and virus binding do not completely overlap. Relative contributions of CVB binding affinity, receptor binding footprint on the virus capsid, and induction of capsid conformation alterations for the ability of cellular DAF and CAR to act as receptors are discussed.

scholarly journals The Coxsackievirus and Adenovirus Receptor: Glycosylation and the Extracellular D2 Domain Are Not Required for Coxsackievirus B3 Infection

2016 ◽  
Vol 90 (12) ◽  
pp. 5601-5610 ◽  
Author(s):  
Sandra Pinkert ◽  
Carsten Röger ◽  
Jens Kurreck ◽  
Jeffrey M. Bergelson ◽  
Henry Fechner
Keyword(s):  
Virus Infection ◽  
Immunoglobulin Superfamily ◽  
Minor Importance ◽  
Receptor Function ◽  
Virus Binding ◽  
D2 Domain ◽  
Cvb3 Infection ◽  
Coxsackie B Viruses ◽  
Coxsackievirus And Adenovirus Receptor ◽  
Adenovirus Receptor

ABSTRACTThe coxsackievirus and adenovirus receptor (CAR) is a member of the immunoglobulin superfamily (IgSF) and functions as a receptor for coxsackie B viruses (CVBs). The extracellular portion of CAR comprises two glycosylated immunoglobulin-like domains, D1 and D2. CAR-D1 binds to the virus and is essential for virus infection; however, it is not known whether D2 is also important for infection, and the role of glycosylation has not been explored. To understand the function of these structural components in CAR-mediated CVB3 infection, we generated a panel of human (h) CAR deletion and substitution mutants and analyzed their functionality as CVB receptors, examining both virus binding and replication. Lack of glycosylation of the CAR-D1 or -D2 domains did not adversely affect CVB3 binding or infection, indicating that the glycosylation of CAR is not required for its receptor functions. Deletion of the D2 domain reduced CVB3 binding, with a proportionate reduction in the efficiency of virus infection. Replacement of D2 with the homologous D2 domain from chicken CAR, or with the heterologous type C2 immunoglobulin-like domain from IgSF11, another IgSF member, fully restored receptor function; however, replacement of CAR-D2 with domains from CD155 or CD80 restored function only in part. These data indicate that glycosylation of the extracellular domain of hCAR plays no role in CVB3 receptor function and that CAR-D2 is not specifically required. The D2 domain may function largely as a spacer permitting virus access to D1; however, the data may also suggest that D2 affects virus binding by influencing the conformation of D1.IMPORTANCEAn important step in virus infection is the initial interaction of the virus with its cellular receptor. Although the role in infection of the extracellular CAR-D1, cytoplasmic, and transmembrane domains have been analyzed extensively, nothing is known about the function of CAR-D2 and the extracellular glycosylation of CAR. Our data indicate that glycosylation of the extracellular CAR domain has only minor importance for the function of CAR as CVB3 receptor and that the D2 domain is not essential per se but contributes to receptor function by promoting the exposure of the D1 domain on the cell surface. These results contribute to our understanding of the coxsackievirus-receptor interactions.

scholarly journals CD16a with oligomannose-type N-glycans is the only “low-affinity” Fc γ receptor that binds the IgG crystallizable fragment with high affinity in vitro

2018 ◽  
Vol 293 (43) ◽  
pp. 16842-16850 ◽  
Author(s):  
Ganesh P. Subedi ◽  
Adam W. Barb
Keyword(s):  
Immune Response ◽  
Binding Affinity ◽  
Fold Increase ◽  
The Other ◽  
Amino Acid Residues ◽  
Complex Type ◽  
High Affinity ◽  
Glycosylation Sites ◽  
Carbohydrate Chains

Fc γ receptors (FcγRs) bind circulating IgG (IgG1) at the surface of leukocytes. Antibodies clustered at the surface of a targeted particle trigger a protective immune response through activating FcγRs. Three recent reports indicate that the composition of the asparagine-linked carbohydrate chains (N-glycans) of FcγRIIIa/CD16a impacted IgG1-binding affinity. Here we determined how N-glycan composition affected the affinity of the “low-affinity” FcγRs for six homogeneous IgG1 Fc N-glycoforms (G0, G0F, G2, G2F, A2G2, and A2G2F). Surprisingly, CD16a with oligomannose N-glycans bound to IgG1 Fc (A2G2) with a KD = 1.0 ± 0.1 nm. This affinity represents a 51-fold increase over the affinity measured for CD16a with complex-type N-glycans (51 ± 8 nm) and is comparable with the affinity of FcγRI/CD64, the sole “high-affinity” FcγR. CD16a N-glycan composition accounted for increases in binding affinity for the other IgG1 Fc glycoforms tested (10–50-fold). This remarkable sensitivity could only be eliminated by preventing glycosylation at Asn162 with an Asn-to-Gln mutation; mutations at the four other N-glycosylation sites preserved tighter binding in the Man5 glycoform. None of the other low-affinity FcγRs showed more than a 3.1-fold increase upon modifying the receptor N-glycan composition, including CD16b, which differs from CD16a by only four amino acid residues. This result indicates that CD16a is unique among the low-affinity FcγRs, and modifying only the glycan composition of both the IgG1 Fc ligand and receptor provides a 400-fold range in affinities.

scholarly journals Cell Surface Proteoglycans Are Necessary for A27L Protein-Mediated Cell Fusion: Identification of the N-Terminal Region of A27L Protein as the Glycosaminoglycan-Binding Domain

1998 ◽  
Vol 72 (10) ◽  
pp. 8374-8379 ◽  
Author(s):  
Jye-Chian Hsiao ◽  
Che-Sheng Chung ◽  
Wen Chang
Keyword(s):  
Virus Infection ◽  
Cell Surface ◽  
Vaccinia Virus ◽  
Heparan Sulfate ◽  
Cell Fusion ◽  
Binding Domain ◽  
Terminal Region ◽  
Virus Binding ◽  
Vaccinia Virus Infection

ABSTRACT We previously showed that vaccinia virus infection of BSC40 cells was blocked by soluble heparin, suggesting that cell surface heparan sulfate mediates vaccinia virus binding (C.-S. Chung, J.-C. Hsiao, Y.-S. Chang, and W. Chang, J. Virol. 72:1577–1585, 1998). In this study, we extended our previous work and demonstrated that soluble A27L protein bound to heparan sulfate on cells and interfered with vaccinia virus infection at a postbinding step. In addition, we investigated the structure of A27L protein that provides for its binding to heparan sulfate on cells. A mutant of A27L protein, named D-A27L, devoid of a cluster of 12 amino acids rich in basic residues, was constructed. In contrast to the soluble A27L protein, purified D-A27L protein was inactive in all of our assays, including binding to heparin in vitro, binding to heparan sulfate on cells, and the ability to block virus infection. These data demonstrated that the N-terminal region acts as a glycosaminoglycan (GAG)-binding domain critical for A27L protein binding to cells. Previously A27L protein was thought to be involved in fusion of virus-infected cells induced by acid treatment. When we investigated whether cell surface GAGs also participate in A27L-dependent fusion, our results indicated that soluble A27L protein blocked cell fusion, whereas D-A27L protein did not. Taken together, the results therefore demonstrated that A27L-mediated cell fusion is triggered by its interaction with cell surface GAGs through the N-terminal domain.

scholarly journals A27L Protein Mediates Vaccinia Virus Interaction with Cell Surface Heparan Sulfate

1998 ◽  
Vol 72 (2) ◽  
pp. 1577-1585 ◽  
Author(s):  
Che-Sheng Chung ◽  
Jye-Chian Hsiao ◽  
Yuan-Shau Chang ◽  
Wen Chang
Keyword(s):  
Virus Infection ◽  
Cell Surface ◽  
Vaccinia Virus ◽  
Heparan Sulfate ◽  
Mammalian Cells ◽  
Myxoma Virus ◽  
Cowpox Virus ◽  
Virus Binding ◽  
Vaccinia Virus Infection

ABSTRACT Vaccinia virus has a wide host range and infects mammalian cells of many different species. This suggests that the cell surface receptors for vaccinia virus are ubiquitously expressed and highly conserved. Alternatively, different receptors are used for vaccinia virus infection of different cell types. Here we report that vaccinia virus binds to heparan sulfate, a glycosaminoglycan (GAG) side chain of cell surface proteoglycans, during virus infection. Soluble heparin specifically inhibits vaccinia virus binding to cells, whereas other GAGs such as condroitin sulfate or dermantan sulfate have no effect. Heparin also blocks infections by cowpox virus, rabbitpox virus, myxoma virus, and Shope fibroma virus, suggesting that cell surface heparan sulfate could be a general mediator of the entry of poxviruses. The biochemical nature of the heparin-blocking effect was investigated. Heparin analogs that have acetyl groups instead of sulfate groups also abolish the inhibitory effect, suggesting that the negative charges on GAGs are important for virus infection. Furthermore, BSC40 cells treated with sodium chlorate to produce undersulfated GAGs are more refractory to vaccinia virus infection. Taken together, the data support the notion that cell surface heparan sulfate is important for vaccinia virus infection. Using heparin-Sepharose beads, we showed that vaccinia virus virions bind to heparin in vitro. In addition, we demonstrated that the recombinant A27L gene product binds to the heparin beads in vitro. This recombinant protein was further shown to bind to cells, and such interaction could be specifically inhibited by soluble heparin. All the data together indicated that A27L protein could be an attachment protein that mediates vaccinia virus binding to cell surface heparan sulfate during viral infection.

Increased Protein Synthesis by Human Platelets during Phagocytosis of Latex Particles in Vitro

1976 ◽  
Vol 35 (02) ◽  
pp. 350-357 ◽  
Author(s):  
Hana Bessler ◽  
Galila Agam ◽  
Meir Djaldetti
Keyword(s):  
Protein Synthesis ◽  
Fold Increase ◽  
Human Platelets ◽  
Polystyrene Latex ◽  
Latex Particles ◽  
The Third ◽  
Platelet Protein ◽  
Dose Dependent ◽  
Phagocytotic Activity

SummaryA three-fold increase of protein synthesis by human platelets during in vitro phagocytosis of polystyrene latex particles was detected. During the first two hours of incubation, the percentage of phagocytizing platelets and the number of latex particles per platelet increased; by the end of the third hour, the first parameter remained stable, while the number of latex particles per cell had decreased.Vincristine (20 μg/ml of cell suspension) inhibited platelet protein synthesis. This effect was both time- and dose-dependent. The drug also caused a decrease in the number of phagocytizing cells, as well as in their phagocytotic activity.

Monitoring Anticoagulant Therapy by Activated Partial Thromboplastin Time: Hirudin Assessment

1994 ◽  
Vol 72 (05) ◽  
pp. 685-692 ◽  
Author(s):  
Michael T Nurmohamed ◽  
René J Berckmans ◽  
Willy M Morriën-Salomons ◽  
Fenny Berends ◽  
Daan W Hommes ◽  
...  
Keyword(s):  
Whole Blood ◽  
Partial Thromboplastin Time ◽  
Ex Vivo ◽  
Fold Increase ◽  
Heparin Therapy ◽  
Activated Partial Thromboplastin Time ◽  
Recombinant Hirudin ◽  
Interindividual Differences ◽  
The Relationship

SummaryBackground. Recombinant hirudin (RH) is a new anticoagulant for prophylaxis and treatment of venous and arterial thrombosis. To which extent the activated partial thromboplastin time (APTT) is suitable for monitoring of RH has not been properly evaluated. Recently, a capillary whole blood device was developed for bed-side monitoring of the APTT and it was demonstrated that this device was suitable to monitor heparin therapy. However, monitoring of RH was not evaluated.Study Objectives. To evaluate in vitro and ex vivo the responsiveness and reproducibility for hirudin monitoring of the whole blood monitor and of plasma APTT assays, which were performed with several reagents and two conventional coagulometers.Results. Large interindividual differences in hirudin responsiveness were noted in both the in vitro and the ex vivo experiments. The relationship between the APTT, expressed as clotting time or ratio of initial and prolonged APTT, and the hirudin concentration was nonlinear. A 1.5-fold increase of the clotting times was obtained at 150-200 ng/ml plasma. However, only a 2-fold increase was obtained at hirudin levels varying from 300 ng to more than 750 ng RH/ml plasma regardless of the assays. The relationship linearized upon logarithmic conversion of the ratio and the hirudin concentration. Disregarding the interindividual differences, and presuming full linearity of the relationship, all combinations were equally responsive to hirudin.Conclusions. All assays were equally responsive to hirudin. Levels up to 300 ng/ml plasma can be reliably estimated with each assay. The manual device may be preferable in situations where rapid availability of test results is necessary.

Gene transfer of endothelial NO-synthase restores migratory capacity of endothelial progenitor cells from patients with coronary artery diseases

2007 ◽  
Vol 30 (4) ◽  
pp. 96
Author(s):  
Michael R. Ward ◽  
Qiuwang Zhang ◽  
Duncan J. Stewart ◽  
Michael J.B. Kutryk
Keyword(s):  
Risk Factors ◽  
Progenitor Cells ◽  
Endothelial Progenitor Cells ◽  
Fold Increase ◽  
No Synthase ◽  
Endothelial Progenitor ◽  
Migratory Capacity ◽  
Acute Mi ◽  
Cad Risk

Autologous endothelial progenitor cells (EPCs) have been used extensively in the development of cell-based therapy for acute MI. However, EPCs isolated from patients with CAD and/or CAD risk factors have reduced regenerative activity compared to cells from healthy subjects. As in endothelial cells, endothelial NO synthase (eNOS) expression and subsequent NO production are believed to be critical determinants of EPC function. Recently, the ability of EPCs to migrate in vitro in response to chemotactic stimuli has been shown to predict their regenerative capacity in clinical studies. Therefore, we hypothesized that the regenerative function of EPCs from patients with or at high risk for CAD will be enhanced by overexpression of eNOS, as assessed by migratory capacity. Methods: EPCs were isolated from the blood of human subjects with CAD risk factors (>15% Framingham risk score; FRS) (± CAD) by Ficoll gradient separation and differential culture. Following 3 days in culture, cells were transduced using lentivirus vectors containing either eNOS or GFP (sham) at an MOI of 3. The cells were cultured for an additional 5 days before being used in functional assays. Cell migration and chemotaxis in response to VEGF (50 ng/mL) and SDF-1 (100 ng/mL) were assessed using a modified Boyden Chamber assay. Results: Transduction at an MOI of 3 led to a ~90-100-fold increase in eNOS mRNA expression and a 5-6 fold increase in eNOS protein expression, as assessed by qRT-PCR and Western Blotting. Moreover, there was a significant improvement in the migration of EPCs following eNOS transduction compared to sham-transduced EPCs in response to both VEGF (44.3 ± 8.4 vs. 31.1 ± 4.6 cells/high power field; n=10, p < 0.05) and SDF-1 (51.9 ± 11.1 vs. 34.5 ± 3.3 cells/HPF; n=10, p < 0.05). Conclusions: These data show that the reduced migration capacity of EPCs isolated from patients with CAD and/or CAD risk factors can be significantly improved through eNOS overexpression in these cells. Thus, eNOS transduction of autologous EPCs may enhance their ability to restore myocardial perfusion and function following acute MI. We intend to further explore the regenerative potential of eNOS-transduced EPCs using various in vitro and in vivo models.

Improved Production of Two Anti-Candida Lipopeptide Homologues Co- Produced by the Wild-Type Bacillus subtilis RLID 12.1 under Optimized Conditions

2020 ◽  
Vol 21 (5) ◽  
pp. 438-450
Author(s):  
Ramya Ramchandran ◽  
Swetha Ramesh ◽  
Anviksha A ◽  
RamLal Thakur ◽  
Arunaloke Chakrabarti ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Pathogenic Fungi ◽  
Fold Increase ◽  
Production Yield ◽  
Yield Enhancement ◽  
Bioactive Metabolites ◽  
Candida Auris ◽  
Media Formulation ◽  
Static Conditions

Background:: Antifungal cyclic lipopeptides, bioactive metabolites produced by many species of the genus Bacillus, are promising alternatives to synthetic fungicides and antibiotics for the biocontrol of human pathogenic fungi. In a previous study, the co- production of five antifungal lipopeptides homologues (designated as AF1, AF2, AF3, AF4 and AF5) by the producer strain Bacillus subtilis RLID 12.1 using unoptimized medium was reported; though the two homologues AF3 and AF5 differed by 14 Da and in fatty acid chain length were found effective in antifungal action, the production/ yield rate of these two lipopeptides determined by High-Performance Liquid Chromatography was less in the unoptimized media. Methods:: In this study, the production/yield enhancement of the two compounds AF3 and AF5 was specifically targeted. Following the statistical optimization (Plackett-Burman and Box-Behnken designs) of media formulation, temperature and growth conditions, the production of AF3 and AF5 was improved by about 25.8- and 7.4-folds, respectively under static conditions. Results:: To boost the production of these two homologous lipopeptides in the optimized media, heat-inactivated Candida albicans cells were used as a supplement resulting in 34- and 14-fold increase of AF3 and AF5, respectively. Four clinical Candida auris isolates had AF3 and AF5 MICs (100 % inhibition) ranging between 4 and 16 μg/ml indicating the lipopeptide’s clinical potential. To determine the in vitro pharmacodynamic potential of AF3 and AF5, time-kill assays were conducted which showed that AF3 (at 4X and 8X concentrations) at 48h exhibited mean log reductions of 2.31 and 3.14 CFU/ml of C. albicans SC 5314, respectively whereas AF5 at 8X concentration showed a mean log reduction of 2.14 CFU/ml. Conclusion:: With the increasing threat of multidrug-resistant yeasts and fungi, these antifungal lipopeptides produced by optimized method promise to aid in the development of novel antifungal that targets disease-causing fungi with improved efficacy.

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