scholarly journals Fusion and Infection of Influenza and Sendai Viruses as Modulated by Dextran Sulfate: A Comparative Study

2001 ◽  
Vol 21 (3) ◽  
pp. 293-304 ◽  
Author(s):  
João Ramalho-Santos ◽  
Maria C. Pedroso de Lima
Keyword(s):  
Molecular Weight ◽  
Dextran Sulfate ◽  
Sendai Virus ◽  
Mdck Cells ◽  
Inhibitory Effect ◽  
Low Ph ◽  
Influenza Viruses ◽  
Target Cells ◽  
Fusion Activity ◽  
Viral Envelopes

We have directly compared the effect of two types of dextran sulfate with distinct molecular weights (500 kDa and 5 kDa) on the fusion activity and infectivity of both Sendai and influenza viruses, two lipid-enveloped viruses that differ in their routes of entry into target cells. To correlate membrane merging and infectivity MDCK cells were used as targets for the viruses in both approaches. In either case pronounced inhibition of virus–cell interactions by dextran sulfate was only observed at low pH, even though Sendai virus fuses maximally at pH 7.4. Although membrane merging could not be fully abolished, the inhibitory effect was always greater when the higher molecular weight dextran sulfate was used. The presence of this residual fusion activity, that could not be reduced even with high concentrations of agent, suggests that a limited number of binding sites for dextran sulfate may exist on the viral envelopes. The compounds also inhibited fusion of bound virions, and all results could be reproduced using erythrocyte ghosts as target membranes in the fusion assay, instead of MDCK cells. In agreement with these observations only the infectivity of influenza virus (which requires a low pH-dependent step to enter target cells) was affected by dextran sulfate, again the higher molecular weight compound showing a more pronounced inhibitory effect.

scholarly journals Coreceptor-Dependent Inhibition of the Cell Fusion Activity of Simian Immunodeficiency Virus Env Proteins

2000 ◽  
Vol 74 (13) ◽  
pp. 6217-6222 ◽  
Author(s):  
Chinglai Yang ◽  
Qingyuan Yang ◽  
Richard W. Compans
Keyword(s):  
Simian Immunodeficiency Virus ◽  
Hela Cells ◽  
Leukemia Virus ◽  
Inhibitory Effect ◽  
Peptide Sequence ◽  
Target Cells ◽  
Fusion Activity ◽  
Immunodeficiency Virus ◽  
Dependent Inhibition ◽  
Env Protein

ABSTRACT The cytoplasmic tail (R peptide) sequence is able to regulate the fusion activity of the murine leukemia virus (MuLV) envelope (Env) protein. We have previously shown that this sequence exerts a profound inhibitory effect on the fusion activity of simian immunodeficiency virus (SIV)-MuLV chimeric Env proteins which contain the extracellular and transmembrane domains of the SIV Env protein. Recent studies have shown that SIV can utilize several alternative cellular coreceptors for its fusion and entry into the cell. We have investigated the fusion activity of SIV and SIV-MuLV chimeric Env proteins using cells that express different coreceptors. HeLa cells were transfected with plasmid constructs that carry the SIV or SIV-MuLV chimeric Env protein genes and were overlaid with either CEMx174 cells or Ghost Gpr15 cells, which express the Gpr15 coreceptor for SIV, or Ghost CCR5 cells, which express CCR5, an alternate coreceptor for SIV. The R-peptide sequence in the SIV-MuLV chimeric proteins was found to inhibit the fusion with CEMx174 cells or Ghost Gpr15 cells. However, a significant level of fusion was still observed when HeLa cells expressing the chimeric Env proteins were cocultivated with Ghost CCR5 cells. These results show that the R-peptide sequence exerts differential effects on the fusion activity of SIV Env proteins using target cells that express alternative coreceptors.

scholarly journals H1N1 Swine Influenza Viruses Differ from Avian Precursors by a Higher pH Optimum of Membrane Fusion

2015 ◽  
Vol 90 (3) ◽  
pp. 1569-1577 ◽  
Author(s):  
Jan Baumann ◽  
Nancy Mounogou Kouassi ◽  
Emanuela Foni ◽  
Hans-Dieter Klenk ◽  
Mikhail Matrosovich
Keyword(s):  
Membrane Fusion ◽  
Conformational Transition ◽  
H1n1 Virus ◽  
Mdck Cells ◽  
Conformational Stability ◽  
Influenza Viruses ◽  
Interspecies Transmission ◽  
Fusion Activity ◽  
Ph Optimum ◽  
New Host

ABSTRACTThe H1N1 Eurasian avian-like swine (EAsw) influenza viruses originated from an avian H1N1 virus. To characterize potential changes in the membrane fusion activity of the hemagglutinin (HA) during avian-to-swine adaptation of the virus, we studied EAsw viruses isolated in the first years of their circulation in pigs and closely related contemporary H1N1 viruses of wild aquatic birds. Compared to the avian viruses, the swine viruses were less sensitive to neutralization by lysosomotropic agent NH4Cl in MDCK cells, had a higher pH optimum of hemolytic activity, and were less stable at acidic pH. Eight amino acid substitutions in the HA were found to separate the EAsw viruses from their putative avian precursor; four substitutions—T492S, N722D, R752K, and S1132F—were located in the structural regions of the HA2 subunit known to play a role in acid-induced conformational transition of the HA. We also studied low-pH-induced syncytium formation by cell-expressed HA proteins and found that the HAs of the 1918, 1957, 1968, and 2009 pandemic viruses required a lower pH for fusion induction than did the HA of a representative EAsw virus. Our data show that transmission of an avian H1N1 virus to pigs was accompanied by changes in conformational stability and fusion promotion activity of the HA. We conclude that distinctive host-determined fusion characteristics of the HA may represent a barrier for avian-to-swine and swine-to-human transmission of influenza viruses.IMPORTANCEContinuing cases of human infections with zoonotic influenza viruses highlight the necessity to understand which viral properties contribute to interspecies transmission. Efficient binding of the HA to cellular receptors in a new host species is known to be essential for the transmission. Less is known about required adaptive changes in the membrane fusion activity of the HA. Here we show that adaptation of an avian influenza virus to pigs in Europe in 1980s was accompanied by mutations in the HA, which decreased its conformational stability and increased pH optimum of membrane fusion activity. This finding represents the first formal evidence of alteration of the HA fusion activity/stability during interspecies transmission of influenza viruses under natural settings.

scholarly journals Involvement of fusion activity of ultraviolet light-inactivated sendai virus in formation of target antigens recognized by cytotoxic T cells

1978 ◽  
Vol 148 (1) ◽  
pp. 276-287 ◽  
Author(s):  
K Sugamura ◽  
K Shimizu ◽  
FH Back
Keyword(s):  
T Cells ◽  
Ultraviolet Light ◽  
Sendai Virus ◽  
Cytotoxic T Cells ◽  
Target Antigen ◽  
Target Cells ◽  
Fusion Activity ◽  
Ethanol Treatment ◽  
Specific Lysis

Mice inoculated with ultraviolet light-inactivated Sendai virus mount a cell- mediated immune response to the virus. Cytotoxic T cells specific for Sendai virus can be obtained by in vitro secondary stimulation of primed spleen cells with syngeneic stimulator cells coated with UV-inactivated Sendai virus. Neither in vivo nor in vitro stimulation alone is sufficient to generate specific cytotoxic T cells. Sharing of the H-2 haplotype between cytotoxic T cells and target cells is required for the Sendai virus-specific lysis to occur. The fusion (F) glycoprotein of Sendai virus has been implicated in target antigen formation (20). Ethanol treatment of Sendai virus causes complete inactivation of the cell-fusion and hemolytic activities of the envelope, but does not affect the antigenicity of the F glycoprotein; furthermore, hemagglutinin and neuraminidase activities of the envelope HANA glycoprotein are also left intact after ethanol treatment. Target cells can be prepared by coating them with various numbers of UV-inactivated Sendai virus that have been treated with ethanol or, as a control, phosphate-buffered saline (PBS). The amount of virus adsorbed to target cells during the cytotoxicity reaction time using either ethanol-treated or untreated (PBS "treated") virions is essentially identical, but target cells coated with ethanol-treated Sendai virus fail to serve as targets for cytotoxic T cells. These results indicate that fusion activity of the Sendai virus envelope is essential to the formation of the target antigen and that virus adsorption to cell surfaces without fusion of the envelope with cell membranes is not sufficient to allow killing by virus-specific cytotoxic T cells.

Cell Function, Viability, and Icodextrin

1994 ◽  
Vol 14 (2_suppl) ◽  
pp. 28-32 ◽  
Author(s):  
Nicholas Topley ◽  
Tomasz Liberek ◽  
Chandra Mistry ◽  
Gerald A. Coles ◽  
John D. Williams
Keyword(s):  
Molecular Weight ◽  
Cell Function ◽  
Inhibitory Effect ◽  
Low Ph ◽  
Laboratory Setting ◽  
Novel Approach ◽  
Glucose Polymer ◽  
Per Se ◽  
Dialysis Fluids ◽  
High Lactate

The bioincompatibility of conventional dialysis fluids is related primarily to the combination of low pH and high lactate concentrations. This results in the reduction of intracellular pH and a consequent inhibition of cell function. The use of high glucose concentrations to increase fluid osmolality adds to the cytotoxicity and has a further inhibitory effect on peritoneal cells. The clinical need for fluids that provide sustained ultrafiltration has led to a novel approach using a high molecular weight glucose polymer (icodextrin) to generate an ultrafiltration gradient in an iso-osmolar fluid. In the studies presented we have had the opportunity of examining, in the laboratory setting, the biocompatibility of such a fluid. As in previous studies with conventional fluids, pH per se has a profound effect on most modalities of cell function. In addition, there appearto be a few areas where problems can be ascribed to icodextrin itself. Furthermore, it is possible that Staph. epidermidis survives better in icodextrin than in conventional dialysate. Whether the benefits of sustained ultrafiltration outweigh the possible disadvantages outlined can only be judged when the results from ongoing clinical trials are available.

Analysis of Intrinsic Fibrinolysis in Human Plasma Induced by Dextran Sulfate

1992 ◽  
Vol 67 (04) ◽  
pp. 440-444 ◽  
Author(s):  
Hiroko Tsuda ◽  
Toshiyuki Miyata ◽  
Sadaaki Iwanaga ◽  
Tetsuro Yamamoto
Keyword(s):  
Molecular Weight ◽  
Human Plasma ◽  
Dextran Sulfate ◽  
Tissue Type ◽  
Factor Xii ◽  
Normal Human Plasma ◽  
High Molecular Weight Kininogen ◽  
Single Chain ◽  
Major Pathway ◽  
Normal Human

SummaryThe analysis of normal human plasma by fibrin autography revealed four species of plasminogen activator (PA) activity related to tissue-type PA, factor XII, prekallikrein and urokinase-type PA (u-PA). The u-PA activity increased significantly by incubating plasma with dextran sulfate. This increase was coincident with both the cleavage of factor XII and the complex formation of activated factor XII with its plasma inhibitors, which were determined by immunoblotting procedure. The dextran sulfate-dependent activation of u-PA required both factor XII and prekallikrein, but did not require either plasminogen or factor XI. High molecular weight kininogen was required only at a low concentration of dextran sulfate. Thus the results indicate that the factor XII and prekallikrein-mediated activation of single chain u-PA (scu-PA) operates as a major pathway of scu-PA activation in whole plasma in contact with dextran sulfate.

Toxicity of Heparinoids, with Special Reference to the Precipitation of Fibrinogen

1964 ◽  
Vol 12 (01) ◽  
pp. 232-261 ◽  
Author(s):  
S Sasaki ◽  
T Takemoto ◽  
S Oka
Keyword(s):  
Molecular Weight ◽  
Dextran Sulfate ◽  
Anticoagulant Activity ◽  
Molecular Structures ◽  
Severe Reaction ◽  
Clinical Use ◽  
Molecular Weights ◽  
Close Relationship

SummaryTo demonstrate whether the intravascular precipitation of fibrinogen is responsible for the toxicity of heparinoid, the relation between the toxicity of heparinoid in vivo and the precipitation of fibrinogen in vitro was investigated, using dextran sulfate of various molecular weights and various heparinoids.1. There are close relationships between the molecular weight of dextran sulfate, its toxicity, and the quantity of fibrinogen precipitated.2. The close relationship between the toxicity and the precipitation of fibrinogen found for dextran sulfate holds good for other heparinoids regardless of their molecular structures.3. Histological findings suggest strongly that the pathological changes produced with dextran sulfate are caused primarily by the intravascular precipitates with occlusion of the capillaries.From these facts, it is concluded that the precipitates of fibrinogen with heparinoid may be the cause or at least the major cause of the toxicity of heparinoid.4. The most suitable molecular weight of dextran sulfate for clinical use was found to be 5,300 ~ 6,700, from the maximum value of the product (LD50 · Anticoagulant activity). This product (LD50 · Anticoagulant activity) can be employed generally to assess the comparative merits of various heparinoids.5. Clinical use of the dextran sulfate prepared on this basis gave satisfactory results. No severe reaction was observed. However, two delayed reactions, alopecia and thrombocytopenia, were observed. These two reactions seem to come from the cause other than intravascular precipitation.

scholarly journals Inhibitory effect of low-molecular-weight peptides (0–3 kDa) from Spirulina platensis on H2O2-induced oxidative damage in L02 human liver cells

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Jun Ma ◽  
Xiankun Zeng ◽  
Min Zhou ◽  
Le Cheng ◽  
Difeng Ren
Keyword(s):  
Molecular Weight ◽  
Oxidative Damage ◽  
Spirulina Platensis ◽  
Radical Scavenging ◽  
Inhibitory Effect ◽  
Control Group ◽  
Low Molecular Weight ◽  
Sod Activity ◽  
Liver Health ◽  
L02 Cells

AbstractSpirulina platensis protein hydrolysates were prepared by digesting protein extracts with papain, and the hydrolysates were separated into 30, 10, and 3 kDa weights using membrane ultrafiltration. The 0–3 kDa low-molecular-weight Spirulina peptides (LMWSPs) proved the highest chemical antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, hydroxyl radical (·OH) scavenging activities and total antioxidant capacity. Cellular antioxidant ability of LMWPs fractions against 2000 μg/mL H2O2 induced oxidative damage of L02 cells were investigated. The MTT assay results displayed that LMWSPs at different concentrations (0–1000 μg/mL) had proliferation effect on the L02 cells and that treatment of the L02 cells with the 1000 μg/mL LMWSPs (0–3 kDa) significantly prevented H2O2-induced oxidative damage compared with control cells. Moreover, the 2′,7′-dichlorofluorescein diacetate (DCFH-DA) fluorescent probe assay showed that the levels of ROS and NO were significantly lower in the experimental group that was treated with the peptides for 24 h than in the control group. Furthermore, using the corresponding kits, the treatment inhibited the reduction of SOD activity and the increase of MDA contents in the L02 cells. Therefore, LMWSPs (0–3 kDa) may have potential applications in antioxidant and liver health products.

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