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PubMed1999

An analysis of the role of neuraminidase in the receptor-binding activity of influenza B virus: the inhibitory effect of Zanamivir on haemadsorption.

We analysed the role of neuraminidase (NA) on haemadsorption by the haemagglutinin (HA) protein of influenza B virus. The influenza B virus mutant ts-7 has a temperature-sensitive mutation in the NA protein. At high temperature, cells infected with this virus did not exhibit haemadsorption activity, but the addition of bacterial neuraminidase (bNA) restored haemadsorption activity. COS cells transfected with HA cDNAs of B/Kanagawa/73 or B/Lee/40 virus showed no evidence of haemadsorption. However, with the addition of bNA or co- transfection with NA cDNA of the B/Lee/40 virus, haemadsorption was observed. Experiments with point-mutated HA cDNAs of B/Lee/40 virus showed that two N-acetyl glycosylation sites at amino acid residues 160 and 217 were responsible for the inability of the HA protein to adsorb to erythrocytes. These results indicated that haemadsorption by the HA protein of influenza B virus required the involvement of NA. Because the NA inhibitor Zanamivir was reported not to penetrate cells, we investigated the action of this inhibitor and found that Zanamivir inhibited haemadsorption on MDCK cells infected with B/Kanagawa/73 or B/Lee/40 virus. After removing Zanamivir by washing, the addition of bNA restored the haemadsorption activity on the infected cells. Scanning electron microscopy indicated that at 0.4 microM Zanamivir, HA protein did not adsorb to erythrocytes but retained the ability to aggregate virions. However, at 4 microM Zanamivir, distinct virion formation could not be observed.

Adsorption↗

PubMed1999

Amino acid substitutions in a conserved region in the stalk of the Newcastle disease virus HN glycoprotein spike impair its neuraminidase activity in the globular domain.

The ectodomain of the paramyxovirus haemagglutinin-neuraminidase (HN) glycoprotein spike can be divided into two regions: a membrane-proximal, stalk-like structure and a terminal globular domain. The latter contains all the antibody recognition sites of the protein, as well as its receptor recognition and neuraminidase (NA) active sites. These two activities of the protein can be separated by monoclonal antibody functional inhibition studies and mutations in the globular domain. Herein, we show that mutation of several conserved residues in the stalk of the Newcastle disease virus HN protein markedly decrease its NA activity without a significant effect on receptor recognition. Thus, mutations in the stalk, distant from the NA active site in the globular domain, can also separate attachment and NA. These results add to an increasing body of evidence that the NA activity of this protein is dependent on an intact stalk structure.

Adsorption↗

PubMed2002

Characterization of a novel Vibrio pathogenicity island (VPI-2) encoding neuraminidase (nanH) among toxigenic Vibrio cholerae isolates.

Acquisition of virulence genes encoded on mobile genetic elements has played an important role in the emergence of pathogenic isolates of Vibrio cholerae, the causative agent of the diarrhoeal disease cholera. The genes encoding cholera toxin (ctxAB), the main cause of profuse secretory diarrhoea in cholera, are encoded on a filamentous bacteriophage CTXphi. The toxin coregulated pilus (TCP), an essential intestinal colonization factor, was originally designated as part of a pathogenicity island named the Vibrio pathogenicity island (VPI), but this island has more recently been proposed to be the genome of a filamentous phage, VPIphi. In this study, it is shown that nanH, which encodes neuraminidase, maps within a novel pathogenicity island designated VPI-2. The 57.3 kb VPI-2 has all of the characteristic features of a pathogenicity island, including the presence of a bacteriophage-like integrase (int), insertion in a tRNA gene (serine) and the presence of direct repeats at the chromosomal integration sites. Additionally, the G+C content of VPI-2 (42 mol%) is considerably lower than that of the entire genome (47 mol%). VPI-2 encodes several gene clusters, such as a restriction modification system (hsdR and hsdM) and genes required for the utilization of amino sugars (nan-nag region) as well as neuraminidase. To determine the distribution of VPI-2 among V. cholerae, 78 natural isolates were examined using PCR and Southern hybridization analysis for the presence of this region. All toxigenic V. cholerae O1 serogroup isolates examined contained VPI-2, whereas non-toxigenic isolates lacked the island. Of 14 V. cholerae O139 serogroup isolates examined, only one strain, MO2, contained the entire 57.3 kb island, whereas 13 O139 isolates contained only a 20.0 kb region with most of the 5' region of VPI-2 which included nanH deleted in these strains.

Humans↗

PubMed1975

The action of Vibrio cholerae and Corynebacterium diphtheriae neuraminidases on the Sendai virus receptor of human erythrocytes.

Studies of the Sendai virus haemagglutinin receptor on the human erythrocyte surface have confirmed that it involves 2 leads to 3 linked sialic acid. Because the primary specificity of Vibrio cholerae neuraminidase is for this linkage, it is able to compete with the virus for the receptor, to which it adsorbs strongly at low temperatures. Corynebacterium diphtheriae neuraminidase, whose principal specificity is for a sialic acid linkage other than 2 leads to 3, does not easily remove Sendai virus receptors, nor does it adsorb to the erythrocyte surface. A new definition of the term "receptor-destroying enzyme" is given which takes both enzyme and virus specificity into account, and a modified assay method is suggested in order to overcome the problems due to enzyme adsorption.

Antigens, Viral↗

PubMed1981

Effects of hyaluronidase and neuraminidase on immunoreactivity histidine-rich protein in newborn rat epidermis.

Frozen sections of newborn rat skin were treated with a variety of buffers, enzymes, and proteinase inhibitors in order to modify the reactivity of antigenic sites of histidine-rich protein and keratin. By indirect immunofluorescence, we found that antiserum to histidine-rich protein purified from granular cells reacted with keratohyalin granules but not cornified cells treated with hyaluronidase. The same antiserum reacted less distinctly with keratohyalin granules treated with neuraminidase; in contrast, it showed strong reactivity in cornified cells after the neuraminidase digestion. However, the enzyme digestions did not unmask the antigenic site(s) of keratohyalin granules to anti-keratin serum, as did saline in 0.1 M Tris-HCl buffer, pH 8.0. These results suggest that the antigenic site of histidine-rich protein is masked in keratohyalin granules by different mechanisms from the masking of keratin. Histindine-rich protein may be masked primarily with hyaluronic acid in keratohyalin granules, but the sugar moiety appears to be changed to sialic acid in cornified cells.

Animals↗

PubMed1976

Factor VIII and human platelet aggregation. III. Further studies on aggregation of humna platelets by neuraminidase-treated human factor VIII.

When highly purified human factor VIII is submitted to agarose gel chromatography in the presence of 0.5 M CaCl2, the procoagulant activity (low molecular weight factor VIII, LMW-F VIII) is separated from the void volume protein (Vo-VIII). Upon incubation of human factor VIII with purfied neuraminidase, a very stable platelet aggregating activity develops in the "Vo-VIII' fraction, not in the "LMS-FVIII' part. Evidence is provided that the generated aggregating activity is a property of the 'carrier protein' for LMW-F VIII. Desialylated factor VIII retains its antigenic reactivity, its procoagulant or ristocetin cofactor properties and the capacity of its subunits to dissociate and recombine. Neuraminidase-treated human factor VIII, in contrast to intact bovine factor VIII or intact human factor VIII in the presence of restocetin, does not induce aggregation of EDTA-platelet rich plasma, of congenitally afibrinogenaemic platelet rich plasma, nor of washed platelets.

Chromatography, Agarose↗

PubMed1985

Cytotoxicity of lectins on rat intestinal mucosa enhanced by neuraminidase.

The lectins wheat germ agglutinin (WGA) and Concanavalin A (ConA) were perfused into an isolated small intestinal segment alone or after prior perfusion with neuraminidase for a 10 day period in the rat. Intestinal morphometry, intraepithelial Lymphocyte (IEL) and round cell content as well as digestive capacity was measured in the loop and in the adjacent segments. Both lectins induce a mucosal transformation in all segments but ConA is more effective than WGA. Pre-incubation with neuraminidase enhances the action of ConA throughout, whereas only a partial enhancement of the effect of WGA is observed. The mucosal transformation after long term perfusion with the lectins resembles the hyperregenerative adaptation of the mucosa due to gluten in coeliac disease and may thus serve as an animal model for this disease.

Animals↗

PubMed1980

Sialidosis: delineation of subtypes by neuraminidase assay.

A sensitive assay for acid neuraminidase using 4-methylumbelliferyl-alpha-D-N-acetylneuraminic acid is described. In skin fibroblasts, patients with sialidosis Types 1 and 2 have severe deficiencies of neuraminidase activity compared with controls. Patients with Type 1 sialidosis have activities which are 10 times higher than those with Type 2 sialidosis, in keeping with their milder clinical involvement. Two Italian patients with Type I sialidosis had a Km which was one-sixth normal; the other patients had a Km in the normal range.

Cells, Cultured↗

PubMed1988

Acid alpha-neuraminidase deficiency: a nephropathic phenotype?

Isolated neuraminidase deficiency is a member of the relatively rare group of storage disorders known as glycoproteinoses. We report the long-term natural history of the disease in one of the first patients described in the literature. An unusual feature of the disease is the abrupt onset and fulminant nature of the nephrotic syndrome, complications of which caused the demise of our patient. Pathological examination of the kidneys from this child revealed renal epithelial cell damage, most marked in the membranes of the glomeruli and proximal tubules, findings which are consistent with the high sialic acid content of the membrane in these areas of the nephron. Chemical analysis indicated that the bulk of the stored material in the kidney was in the form of polar sialyloligosaccharides of high molecular weight. On the basis of our experience, as well as the previous reports of neuraminidase-deficient patients with nephropathy, we propose a nephropathic phenotypic variant of type 2 infantile sialidosis.

Brain↗

PubMed1989

Characterization of a neuraminidase from Corynebacterium aquaticum responsible for Th polyagglutination.

Th polyagglutinability is characterized by the agglutination of the red blood cells (RBC) by Arachis hypogaea, Medicago disciformis, Vicia cretica but, in contrast to the T phenomenon, not by Glycine max (Glycine soja). Because Th transformation of RBC has been obtained in vitro, the mechanism of Th polyagglutinability expression has been studied and reproduced experimentally. An enzyme with neuraminidase specificity has been isolated from the culture supernatant of Corynebacterium aquaticum, and further characterized (MW = 55,600 kDa, pH = 5.5, Km = 0.138 microM, Kcat = 0.22 micrograms). Reversely, Th transformation of RBC could be obtained by using other neuraminidases but in very mild conditions of hydrolysis. From our results, it can be concluded that by the release of less than 20 micrograms of sialic acid per 10(10) RBC, Th reactivity can be induced whereas hydrolysis of greater amounts of sialic acid (greater than 20 micrograms/10(10) RBC) give the classical T polyagglutinability.

Blood Group Antigens↗

PubMed1980

Purification of haemagglutinin and neuraminidase from influenza virus strain 3QB and isolation of a peptide from an antigenic region of haemagglutinin.

Methods were developed for the purification of the surface, membrane-bound glycoproteins haemagglutinin and neuraminidase of influenza virus strain 3QB, in antigenically active forms. The methods employed in the purification included selective removal of the neuraminidase with the proteinase, bromelain, and subsequent disruption of the residual virus particle with the detergent Sarkosyl to release the haemagglutinin. Using techniques for proteolytic digestion of intact, native proteins an antigenically active peptide was isolated from the purified haemagglutinin, the surface glycoprotein against which the major antigenic response is directed. The amino acid composition of this peptide was determined. This was a 16-residue peptide with amino-terminal isoleucine and composition Ile1 Val1 Asx2 Thr1 Ser2 Glx2 Pro1 Gly3 Ala1 Leu1 Lys1.

Agglutinins↗

PubMed1996

Neuraminidase deficiency presenting as a nephrosialidosis: the first case detected in Poland.

A defect of lysosomal neuraminidase (sialidase N-acetyl-neuramine acid hydrolase EC 3.2.1.18) leads to a wide spectrum of phenotypes, the most severe of which is nephrosialidosis. A 4-year-old boy of related parents, born at term with hydrops fetalis, is reported. Hydrocephalus was detected at 2 months of age. The child's course over 3 years was characterized by slow growth and psychomotor development. He had mild hepatosplenomegaly, joint restriction, gingival hypertrophy, lens opacities and cherry-red spot. Coarse facial features and depressed nasal bridge were discreet. At the age of 3.5 years, he developed gradual progressive edema, decreased activity and increased fatigue. A diagnosis of nephrotic syndrome was made because of massive proteinuria. Thin-layer chromatography of urinary oligosaccharides revealed the presence of several abnormal sialyloligosaccharides. The diagnosis was confirmed by measurement of neuraminidase activity in cultured skin fibroblasts.

Child, Preschool↗

PubMed1983

Neuraminidase in calf retinal outer segment membranes.

An enzyme catalyzing the hydrolysis of sialic acid (N-acetylneuraminic acid: NeuNAc)-containing glycoconjugates has been found in bovine retinal rod outer segment (ROS) membranes. The enzymatic activity is optimal at pH 4.0 and is stimulated by 0.15% Triton X-100. Total activity was determined by the release of NeuNac from endogenous and exogenous substrates (GD1a). The ROS enzyme preferentially hydrolyses the ROS gangliosides, possibly because they are more accessible than the glycoproteins as substrates for the neuraminidase. Release of NeuNAc from gangliosides leads to important changes in the ganglioside patterns; whereas the amounts of GM1 increased throughout the incubation, the levels of polysialogangliosides GT1b and GD3 diminished owing to their rapid hydrolysis. The finding that gangliosides are hydrolysed more extensively than glycoproteins suggests that endogenous ROS gangliosides may be the principal source of metabolically available sialic acid in ROS. It was also observed that the activity of ROS neuraminidase is not affected by illumination of the membranes.

Animals↗

PubMed1983

Temperature-mediated interaction of tetanus toxin with cerebral neuron cultures: characterization of a neuraminidase-insensitive toxin-receptor complex.

Energy-dependent internalization of 125I-labeled tetanus toxin into cultured neural cells is shown to follow an energy-independent binding process. A three-step model, involving receptor-mediated binding followed by sequestration and internalization is proposed. In the first step, binding of toxin is enhanced in appearance under low ionic strength medium, at 0-4 degrees C; it is suppressed, however, with increasing incubation temperature under physiological salt concentrations. Cell-bound toxin is displaced by approximately 35.5% when high-salt medium (physiological concentrations) is added to cells at 0-4 degrees C; the effect is further amplified at 37 degrees C. Addition of disialoganglioside GD1b (1-5 micrograms/ml) also lowers the amount of cell-associated toxin. The fraction of 125I-labeled toxin retained by the cells after exposure to high-salt medium at 0-4 degrees C or after addition of GD1b is operationally defined as sequestered toxin. This second step, characterized by a stable association of the toxin with the neural cells, is affected by both physiological salt and by 37 degrees C conditions. Lastly, an energy-dependent phenomenon of firm association of tetanus toxin with neural cells, compatible with internalization, is described. The toxin residing in this fraction is bioactive and cannot be removed by salts, gangliosides, or by treatment with protease or neuraminidase. Binding, sequestration, and internalization are mutually dependent, as they are all blocked by pretreatment of cells with neuraminidase and by an enhanced energy-independent sequestration event, which results in enhanced tetanus toxin internalization by an energy-dependent process.

Animals↗

PubMed1994

Cloning and expression of the Bacteroides fragilis YCH46 neuraminidase gene in Escherichia coli and Bacteroides uniformis.

A neuraminidase-encoding gene nanH of Bacteroides fragilis strain YCH46 was cloned into the cosmid vector pHC79. The nanH gene was subcloned from the cosmid and was located within a 2.2-kb XhoI-KpnI fragment. Southern hybridization experiments demonstrated that the gene was present as a single copy on the bacterial chromosome. Neuraminidase activity expressed in the initial Escherichia coli clone was approximately 3600-fold lower than that expressed in B. fragilis YCH46. However, when nanH was transferred from E. coli to B. uniformis by mobilization of a shuttle plasmid, the transconjugant expressed 1100-fold higher activity than the E. coli donor did. These results suggest that modes of nanH expression in E. coli and Bacteroides are heterologous.

Bacteroides↗

PubMed1982

Lysis of placental syncytiotrophoblast by allogenic leukocytes in vitro: effects of neuraminidase and chorionic gonadotropin.

51chromium-labeled syncytiotrophoblasts purified from human placentae were lysed by allogenic leukocytes in vitro. The extent of syncytiotrophoblast lysis was dependent upon the dose of the leukocytes, occurred after a lag period of 42 h, and was inhibited by excess of unlabeled syncytiotrophoblasts. Autologous leukocytes failed to lyse syncytiotrophoblasts. Neuraminidase pretreatment of the syncytiotrophoblasts significantly enhanced their lysis by leukocytes. HCG failed to influence the extent of lysis of untreated syncytiotrophoblasts but significantly reduced the lysis of neuraminidase-treated targets. The significance of these observations in relation to the "immunologic privilege" of the trophoblast in vivo is discussed. (Am J Reprod Immunol. 1982; 204-207.)

Chorionic Gonadotropin↗

PubMed1976

The effects of neuraminidase and protamine chloride on potential clamp parameters of the node of Ranvier (Xenopus laevis).

The effects of neuraminidase and protamine chloride on the ionic currents associated with step changes in membrane potential were studied. Neuraminidase (a hydrolase which cleaves glycosidically bound sialic acid) had negligible effects on the permeability properties. The polycation protamine chloride decreased the sodium as well as the potassium currents. The sodium equilibrium potential decreased during the experiments which indicates a gain in internal sodium concentration. The analysis showed that the effects on the currents were caused by a decrease of the specific permeability changes. No shift along the potential axis of the potential dependent parameters was observed.

Action Potentials↗

PubMed1991

Effects of neuropeptides, ruthenium red and neuraminidase on chemoreflexes mediated by afferents in the dog epicardium.

1. Experiments were performed on anaesthetized, open-chest dogs to determine reflex effects on blood pressure and heart rate produced by stimulation of neural afferents of the left ventricular epicardium by local application of capsaicin, bradykinin, nicotine and the neuropeptides substance P (SP), neurokinin A (NKA), neurokinin B (NKB) and calcitonin gene-related peptide (CGRP). 2. Studies also included assessing whether reflexogenic actions of capsaicin, bradykinin and nicotine are influenced by epicardial treatment with either neuropeptides, Ruthenium Red or neuraminidase. 3. Epicardial application of either capsaicin (0.1-10 micrograms) or bradykinin (0.1-1 micrograms), consistently resulted in dose-related increases in blood pressure and heart rate, whereas reflex bradycardia and hypotensive effects were initiated by the application of nicotine (30-50 micrograms). 4. SP, NKA, NKB and CGRP caused marked hypotensive effects and tachycardia when injected intravenously (1 microgram), but failed to produce any cardiovascular response when applied to the epicardium of the left ventricle (0.1-1 microgram). Treatment of the heart surface with these neuropeptides (0.05-0.5 micrograms min-1) was also without any effect on the magnitude of reflex responses evoked by epicardial application of either capsaicin, bradykinin or nicotine. 5. Superfusion of the ventricular epicardium with Ruthenium Red (10-30 microM), a cationic dye known to have sialic acid as a molecular target, antagonized the reflexogenic effects of capsaicin but not those of bradykinin or nicotine. The reflex effects of capsaicin, but not those of bradykinin, were also sensitive to inhibition by epicardial treatment with neuraminidase, an enzyme which cleaves sialic acid residues from glycosides and sialoglycoproteins. 6. We conclude that neuropeptides which may be released from the peripheral endings of some cardiac sensory neurons neither directly activate nor sensitize spinal sympathetic and vagal afferents in the dog heart to the reflexogenic action of bradykinin, nicotine or capsaicin. 7. We further suggest that activation of the cardiac sympathetic chemoreflex by capsaicin involves its interaction with calcium-binding sialic acid moieties present on the surface of axons and/or terminals of chemosensitive sympathetic afferents distributed in the dog ventricular epicardium.

Animals↗