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PubMed1967

Distribution of neuraminidase among food-poisoning strains of Clostridium perfringens.

A survey was made to determine the distribution of the enzyme neuraminidase among 76 strains of Clostridium perfringens. Representative strains from each toxigenic type (A to F) and atypical C. perfringens type A food-poisoning strains of both American and English (Hobbs types) origin were tested. Both the American food-poisoning and nonfood-poisoning associated cultures consisted of both neuraminidase-positive and -negative strains. Furthermore, American strains which could not be differentiated from the original Hobbs cultures consisted of both neuraminidase-positive and -negative representatives. In contrast, the English (Hobbs) strains uniformly failed to produce an active intracellular or extracellular neuraminidase. No enzyme activity was detected in these strains when cultures were grown in different growth media, when grown in the presence of substrate (neuraminlactose), or upon extended incubation of enzyme preparations with substrate. With the exception of a type F strain, representative strains of the other toxigenic types (A to F) produced neuraminidase; 85% of the typical type A strains contained the enzyme.

Clostridium perfringens↗
PubMed1994

In vivo production of neuraminidase by Pasteurella haemolytica A1 in goats after transthoracic challenge.

Nine goats were injected transthoracically with Pasteurella haemolytica A1 to determine if an extracellular bacterial enzyme, neuraminidase, was produced in vivo during infection with this organism. The principal group of goats (n = 9) each received 1 ml of 7.25 x 10(5) live P. haemolytica A1 cells in polyacrylate beads transthoracically in the left lung on days 0 and 21. Six goats were used as negative controls and received 0.3 g of polyacrylate beads subcutaneously in the right flank on days 0 and 21. Serum was obtained from all animals on days -4, 3, 7, 14, 21, 24, and 32. Preimmune serum from all animals showed no detectable antibody to P. haemolytica A1 neuraminidase in an enzyme neutralization assay. None of the sera from the negative control animals possessed a significant antibody concentration in response to the P. haemolytica A1 neuraminidase. On day 32, serum samples from the nine infected animals possessed enzyme neutralizing activity that ranged from 62% to 100%. Anti-neuraminidase antibody could be detected as early as day 14 by the enzyme neutralization assay. These data demonstrate that the enzyme neuraminidase is produced in vivo during an active P. haemolytica A1 lobar infection.

Animals↗
PubMed1994

A neuraminidase from Streptococcus pneumoniae has the features of a surface protein.

A gene from Streptococcus pneumoniae (nanA), with features entirely consistent with a neuraminidase gene, has been sequenced. High levels of neuraminidase activity were obtained after cloning of this gene, without flanking sequences, into a high-expression vector. RNA hybridization studies have shown that the gene is transcribed by a virulent pneumococcus strain. The predicted molecular weight of the protein and certain amino acid sequences are typical of other neuraminidases. NanA contains the four copies of the sequence SXDXGXTW that is present in all the bacterial neuraminidases previously described. Kyte and Doolittle analysis showed that NanA is a hydrophilic protein with hydrophobic domains at the N terminus and the C terminus. A putative signal peptide was found in the N terminus of this protein, indicating that the protein is exported from the pneumococcus. The C terminus has the features of the anchor motif found in other surface proteins from gram-positive bacteria. Electron microscopy studies showed the presence of neuraminidase associated with the cell surface of the pneumococcus.

Amino Acid Sequence↗
PubMed1973

Source of neuraminidase in human whole saliva.

Whole saliva specimens from eight healthy human adults were examined for neuraminidase. The presence of two types of neuraminidase in four samples out of eight was demonstrated by means of polyacrylamide gel electrophoresis and sucrose density gradient centrifugation. One type is soluble and the other an insoluble, perhaps particle-bound, enzyme. The pH optima were 5.8 for the former and 5.0 to 5.3 for the latter. However, the soluble enzyme could not be detected in the other four saliva specimens which showed low activity. A comparative study of the salivary and other neuraminidases was carried out. It was found that both salivary neuraminidases were closely similar to the enzymes in submandibular-sublingual secretions and in human liver, but not to the oral streptococcal enzymes. The results suggest that the salivary neuraminidases might originate from cells such as epithelial cells or polymorphonuclear leukocytes, or both, in the oral cavity.

Centrifugation, Density Gradient↗
PubMed1977

Properties of an inducible extracellular neuraminidase from an Arthrobacter isolate.

The elective isolation of a soil microorganism, tentatively assigned to the genus Arthrobacter, which produced an extracellular neuraminidase is described. The secretion of neuraminidase from washed cells in minimal medium required the presence of sialo-containing glycoproteins, whereas free N-acetyl-neuraminic asid of N-acetylmannosamine were poor inducers. No enzyme could be dected in the induction fitrated of cells, in the absence of inducer or in the culture filtrate of cells grown in a complete medium. The routine enzyme inducer was a hot-water extract of "edible bird's nest." Mild acid treatment (0.05 N H2SO4) of this extract increased enzyme activity two--to threefold and the specific activity about eightfold. Neuraminidase induction with acid-treated bird's nest was manifested at a linear rate for 6 h without increase in cell number. No other anticipated glycohydrolase or protease activities were foud. The amount of enzyme located within the cells was barely detectable as compared to that found in the induction filtrate. Experiments with chloramphenicol or chlortetracycline indicate that de novo protein synthesis was required for neuraminidase production and that this exoenzyme was not released from a preformed pool. Neuraminidase from this source has an apparent molecular weight of 87,000, a pH optimum of 5 to 6, and an apparent Km of 2.08 mg/ml for collocalia mucoid and 3.3 X 10(-3) M for N-acetylneuraminlactose and is insensitive both to Ca2+ ions and ethylenediaminetetraacetic acid. Preliminary studies indicate that the enzyme can hydrolyze alpha-2,3-, alpha-2,6-, or alph-2-8-N-acetylneuraminylglycosidic linkages. From total activity data and purification criteria, it would appear that this isolate can produce about 5 mg of enzyme per liter of induction medium.

Arthrobacter↗
PubMed1992

Cloning, expression, and characterization of the Micromonospora viridifaciens neuraminidase gene in Streptomyces lividans.

We have cloned the Micromonospora viridifaciens neuraminidase (EC 3.2.1.18) gene (nedA) in Streptomyces lividans. This was accomplished by using the vector pIJ702 and BglII-BclI libraries of M. viridifaciens chromosomal inserts created in S. lividans. The libraries were screened for the expression of neuraminidase by monitoring the cleavage of the fluorogenic neuraminidase substrate 2'-(4-methylumbelliferyl)-alpha-D-N-acetyl-neuraminic acid. Positive clones (BG6, BG7, BC4, and BC8) contained the identical 2-kb BclI-BglII fragment and expressed neuraminidase efficiently and constitutively using its own promoter in the heterologous host. From the nucleotide sequence analysis, an open reading frame of 1,941 bp which encodes a polypeptide with an M(r) of 68,840 was detected. The deduced amino acid sequence has five Asp boxes, -Ser-X-Asp-X-Gly-X-Thr-Trp, showing great similarity to other bacterial and viral neuraminidases. We have also identified the catalytic domain by using truncated proteins produced in S. lividans.

Amino Acid Sequence↗
PubMed1968

Protective effects of specific immunity to viral neuraminidase on influenza virus infection of mice.

Antibody specific for viral neuraminidase can be demonstrated in mice following (i) pulmonary infection with influenza virus, (ii) immunization with ultraviolet-in-activated influenza virus, (iii) immunization with isolated neuraminidase of influenza A(2) virus, and (iv) passive immunization with sera of rabbits immunized with isolated A(2) neuraminidase. Neuraminidase antibody produced by any of these methods exerts a profound inhibiting effect on virus replication in the lungs of mice challenged with strains of virus having homologous neuraminidase protein, even in the absence of hemagglutinating inhibiting antibody to the challenge virus, and results in markedly decreased pulmonary virus titers and diminished lung lesions. These observations suggest that antineuraminidase immunity may play a significant role in the protection against influenza virus challenge observed in mice after infection or artificial immunization.

Aerosols↗
PubMed1982

Revertant analysis of a temperature-sensitive mutant of Newcastle disease virus with defective glycoproteins: implication of the fusion glycoprotein in cell killing and isolation of a neuraminidase-deficient hemagglutinating virus.

Biological and molecular properties of a temperature-sensitive mutant (C1) of Newcastle disease virus and its revertants were analyzed. C1 exhibited three temperature-sensitive alterations (plaque formation, virion assembly, and cytopathogenicity) and several defects which were also present at the permissive temperature. C1 virions contained low amounts of hemagglutinin-neuraminidase glycopeptides and consequently were deficient in hemagglutinating and neuraminidase activities. These virions also contained defective fusion glycoproteins which rendered them poorly hemolytic and slow to penetrate cultured chicken embryo cells. The biological activities of the membrane glycoproteins were recovered sequentially in a series of plaque-forming revertants. The coreversion of hemolysis, membrane-penetrating activities, and cytopathogenicity in the first-step revertant (S1) suggested that fusion glycoproteins were major contributors to cellular destruction. This revertant also provided evidence of a role for fusion glycoproteins in virion assembly. From S1 we isolated a large-plaque-forming revertant (L1) that assembled wild-type amounts of biologically active hemagglutinin-neuraminidase glycoproteins into virions. Although it was normal for hemagglutination, L1 had less than 3% of the neuraminidase activity of the wild type, demonstrating that these two activities can be uncoupled genetically. The neuraminidase deficiency of L1 did not impair its virulence in ovo or its reproduction in cultured cells.

Animals↗
PubMed1999

Mutation of neuraminidase cysteine residues yields temperature-sensitive influenza viruses.

The influenza virus neuraminidase (NA) is a tetrameric, virus surface glycoprotein possessing receptor-destroying activity. This enzyme facilitates viral release and is a target of anti-influenza virus drugs. The NA structure has been extensively studied, and the locations of disulfide bonds within the NA monomers have been identified. Because mutation of cysteine residues in other systems has resulted in temperature-sensitive (ts) proteins, we asked whether mutation of cysteine residues in the influenza virus NA would yield ts mutants. The ability to rationally design tight and stable ts mutations could facilitate the creation of efficient helper viruses for influenza virus reverse genetics experiments. We generated a series of cysteine-to-glycine mutants in the influenza A/WSN/33 virus NA. These were assayed for neuraminidase activity in a transient expression system, and active mutants were rescued into infectious virus by using established reverse genetics techniques. Mutation of two cysteines not involved in intrasubunit disulfide bonds, C49 and C146, had modest effects on enzymatic activity and on viral replication. Mutation of two cysteines, C303 and C320, which participate in a single disulfide bond located in the beta5L0,1 loop, produced ts enzymes. Additionally, the C303G and C320G transfectant viruses were found to be attenuated and ts. Because both the C303G and C320G viruses exhibited stable ts phenotypes, they were tested as helper viruses in reverse genetics experiments. Efficiently rescued were an N1 neuraminidase from an avian H5N1 virus, an N2 neuraminidase from a human H3N2 virus, and an N7 neuraminidase from an H7N7 equine virus. Thus, these cysteine-to-glycine NA mutants allow the rescue of a variety of wild-type and mutant NAs into influenza virus.

Amino Acid Substitution↗
PubMed1984

Neuraminidase and contractile responses to norepinephrine in rat tail artery.

Sialic acids are negatively charged groups in the carbohydrate side chains of glycolipids and glycoproteins which line the external membrane surface. The goal of this study was to characterize the effect of neuraminidase, which selectively cleaves sialic acids, on contractile activity in vascular smooth muscle. Helically cut strips of rat tail artery were mounted in an organ chamber and isometric contractions were recorded. Following treatment with neuraminidase (0.2 U/ml, 1 h), contractile responses to norepinephrine were significantly greater than control responses. Phasic contractions to norepinephrine in calcium-free medium were not altered by neuraminidase, whereas following calcium depletion with EGTA, contractile responses to added calcium were greater in enzyme-treated strips than in control when activated with norepinephrine. The augmentation of norepinephrine-induced contractions following neuraminidase treatment was reversed by incubation of the arterial strips with N-acetylneuraminic acid (10(-4) M). Neuraminidase had no effect on contractile responses to potassium chloride, angiotensin II, and caffeine. Biochemical assay indicated that approximately 63% of the total sialic acid residues were removed from the arterial strips during incubation with the enzyme. It is concluded that a component for the control of the transmembrane calcium movement in response to norepinephrine is dependent on the presence of sialic acid residues.

Angiotensin II↗
PubMed1971

Neuraminidase activity in bacterial meningitis.

The relation of neuraminidase to morbidity and mortality was examined in patients with Haemophilus influenzae, meningococcal, and pneumococcal meningitis. Ten strains of H. influenzae and eight strains of meningococci from infected cerebrospinal fluid (CSF) did not elaborate neuraminidase. Each of 27 strains of pneumococci from infected CSF elaborated both neuraminidase and N-acetylneuraminic acid (NANA) aldolase. There was no correlation between amount of neuraminidase secreted in vitro and survival of patients. Values for free and total NANA concentrations were derived from admission CSF samples of 63 patients with meningitis; 18 patients infected with Neisseria meningitidis, 10 with H. influenzae and 35 with Diplococcus pneumoniae. Mean values for total NANA were elevated in each type of bacterial meningitis; however, abnormal concentrations of free CSF NANA were detected only in 17 patients with pneumococcal meningitis. 11 of 18 patients with pneumococcal meningitis showing normal free CSF NANA concentrations were cured, whereas only 4 patients with abnormal free NANA levels survived without residua. Both coma and bacteremia occurred significantly more often among patients with elevated concentrations of free CSF NANA. The association of elevated concentrations of free CSF NANA with coma and with an adverse prognosis suggested that neuraminidase may be a factor in the pathogenesis of penumococcal meningitis.

Cerebrospinal Fluid Proteins↗
PubMed1986

A neuraminidase from Trypanosoma cruzi removes sialic acid from the surface of mammalian myocardial and endothelial cells.

Trypanosoma cruzi causes Chagasic heart disease, a major public health problem in Latin America. The mechanism of interaction of this protozooan parasite with host cells is poorly understood. We recently found that the infective trypomastigote form a T. cruzi exhibits neuraminidase activity and can desialylate mammalian erythrocytes. However, it is not known if T. cruzi can also modify the surfaces of cardiovascular cells that are directly involved in the most important clinical manifestations of this disease. Accordingly, this study determined whether T. cruzi can remove sialic acid from cultured rat myocardial or human vascular endothelial cells. Sialic acid was labeled metabolically with the precursor 3H-N-acetyl-D-mannosamine. Soluble neuraminidase, isolated from intact T. cruzi trypomastigotes, caused significant release of labeled material from myocardial cells (e.g., 2,174 +/- 27 dpm/h vs. spontaneous release of 306 +/- 30 dpm/h, n = 4, P less than 0.001). Chromatographic analysis showed that the bulk of the radioactivity released by T. cruzi neuraminidase was sialic acid. Intact T. cruzi trypomastigotes also released sialic acid from metabolically labeled myocardial cells in a concentration-dependent manner. In contrast, a noninfective form of T. cruzi, the amastigote, did not desialylate these cells. Galactose oxidase labeling demonstrated newly desialylated glycoproteins on the surface of myocardial cells treated with T. cruzi neuraminidase. Desialylation of myocardial cells was confirmed histochemically by the appearance of binding sites for peanut agglutinin, a lectin that binds to complex oligosaccharide moieties after removal of the terminal sialyl residue. T. cruzi neuraminidase also removed sialic acid from adult human saphenous vein endothelial cells, as determined by both histochemical and metabolic labeling studies. Thus, infective forms of T. cruzi can chemically modify the surfaces of myocardial and vascular endothelial cells by desialylation. This alteration may play a role in the initial interaction of this parasite with these important target cells of the host cardiovascular system.

Adult↗
PubMed2003

Logistic issues and potential prescribing costs associated with use of neuraminidase inhibitors for the treatment of influenza in primary care.

In the UK, the National Institute for Clinical Excellence has recommended the use of neuraminidase inhibitors for elderly and at-risk patients who present with influenza-like illness within 36 hours of symptom onset. However, few data exist to enable primary care trusts to evaluate the logistics and costs of prescribing. We sought to determine, during a confirmed influenza outbreak, the proportion of eligible patients who currently present in time to benefit from treatment with a neuraminidase inhibitor, and to develop the findings into a model for evaluating potential prescribing costs. Within a single primary care group, demographic and co-morbidity data were collected on all patients consulting their general practitioner or attending an out-of-hours centre with influenza-like illness during the outbreak period. A typical primary care trust serving 100 000 patients might expect to prescribe a neuraminidase inhibitor to 140 eligible at-risk patients in a season of low influenza activity, rising to 300 in a large epidemic. At-risk patients were more likely than non-at-risk patients to consult within 36 hours of the onset of symptoms. However, only 20% of such patients, rising to 47% in out-of-hours centres, consulted in time to benefit from treatment. The low proportion of elderly and at-risk patients who consult their general practitioner in time to benefit from treatment with a neuraminidase inhibitor emphasizes the overriding importance of annual vaccination in these groups. If the full benefits of neuraminidase inhibitors are to be realized, access to treatment for eligible patients must be improved.

Acetamides↗
PubMed1984

Complementation, cross correction, and drug correction studies of combined beta-galactosidase neuraminidase deficiency in human fibroblasts.

Neuraminidase activity in fibroblasts obtained from a patient with combined beta-galactosidase-neuraminidase deficiency (beta-gal-/neur-) was partially restored by fusion with two ML I cell lines and an ML II cell line. As observed with neuraminidase activity, beta-galactosidase also showed complementation with an increase in activity when beta-gal-/neur- fibroblasts were fused with an ML II or a GMI gangliosidosis cell line. Both GMI gangliosidosis and sialidosis fibroblasts secreted a "corrective factor" which, when added to medium above beta-gal-/neur- fibroblasts, was pinocytosed and partially corrected its deficiencies for these two enzymes. This partial correction of beta-galactosidase and neuraminidase activities persisted for at least 72 h after removal of the "corrective factor" from the medium. A "corrective factor" with similar properties was obtained from glycoproteins isolated by chromatography of human spleen homogenates on concanavalin A-Sepharose. Treatment of beta-gal-/neur- fibroblasts with leupeptin or EP475, two inhibitors of lysosomal thiol-proteases, partially restored beta-galactosidase activity but caused no significant improvement in neuraminidase levels. The partial corrective effect of leupeptin on beta-galactosidase activity persisted for at least 2 d after removal of the drug, even in the presence of cycloheximide.

Fibroblasts↗
PubMed1981

Partial purification and properties of neuraminidase from Bifidobacterium lactentis.

Bifidobacterium lactentis 659 a gram-positive, nonsporeforming anaerobic bacterium originally isolated from the feces of breast-fed infants produces neuraminidase after enzyme induction with 2mM N-acetylmannosamine added to the culture medium. Bacteria were transferred and grown in a medium containing casein hydrolysate, lactose, sodium acetate, amino acids, vitamins, salts and 2% human milk for 48 h at 37 degrees C under N2/CO2 atmosphere. Two subcultures derived from the original strain B. lactentis 659 were investigated separately because of different growth characteristics. However, their taxonomic identity was not doubtful. Neuraminidase was liberated from the bacterial sediments by ultrasonic treatment in 0.15M NaCl and was isolated by 60% ammonium sulfate precipitation, dialysis, concentration, and column chromatography on Sepharose CL-6B and Sephadex G-100. The enzyme exhibits a molecular weight of 38000 and a pH optimum in the range of pH 5--6 in barbital/acetate buffers. Starch gel electrophoresis and neuraminidase-specific staining with NeuAc alpha 2 leads to (3-methoxyphenyl) glycoside revealed two major and three minor enzyme bands. Michaelis constants (Km) were determined to be 7.1 mM for the (alpha 2 leads to 3) linkage of II3NeuAc-Lac, 7.5mM for the (alpha 2 leads to 6) linkage of II6Neu-Ac-Lac and 15mM for the (alpha 2 leads to 8) linkage in II3(leads from 2NeuAc8)2-Lac. Among the different groups of naturally occurring NeuAc-containing substrates, i.e. glycoproteins, gangliosides and oligosaccharides, B. lactentis neuraminidase cleaves oligosaccharides preferentially without remarkable differences between (alpha 2 leads to 3) and (alpha 2 leads to 6) linkages. Globular glycoproteins and mucins are poor substrates and gangliosides are practically not affected. In contrast, enzyme activity towards synthetic NeuAc glycosides is very high. The enzyme is activated by 50% with 50mM Ca2 and inhibited by 20mM EDTA accordingly. In general, B. lactentis neuraminidase shows a substrate specificity pattern similar to those found in other non-pathogenic and non-invasive representatives of the human bacterial flora. The potential biological role of intestinal Bifidobacteria will be discussed.

Actinomycetaceae↗
PubMed1987

Heterogeneity of human luteinizing hormone. Effect of neuraminidase treatment on biologically active hormone and alpha- and beta-subunits.

By preparative isoelectric focussing of a highly purified LH preparation in a sucrose density gradient, four biologically active LH components were isolated. The effect of neuraminidase treatment of each component on the charge heterogeneity was studied by isoelectric focussing followed by in vitro biological and immunochemical techniques. The number of biologically active components with pI-values greater than 7 containing varying amounts of sialic acid is at least six. The pI-value of the most basic (= asialo) LH component was 9.26. The two most basic components were not present in our preparation (NM14) before neuraminidase treatment. It is concluded that the difference between the pI-values of LH components is caused by a difference in sialic acid content. When an intact LH component was incubated with neuraminidase there was detectable dissociation owing to the elevated temperature (37 degrees C) and necessary acidic conditions of the incubation. Under these conditions we found the same subunits as we have described before. The most basic alpha-subunit had a pI-value of 9.29, whereas two beta-subunits with pI greater than 9 were observed at pI 9.26 and pI 9.9. On the other hand, when an LH component was forced to dissociate by incubation at 56 degrees C prior to neuraminidase digestion, two additional alpha-subunits were found. From this it is concluded that in the intact LH molecule, some sialic acid residues are poorer substrates for neuraminidase action than in the free subunits.

Hydrogen-Ion Concentration↗
PubMed1976

On the agglutinogens of red cells developed with proteolytic enzymes and neuraminidase.

It has been known that the agglutinability of human red cells is changed or enhanced by treatments with proteolytic enzymes or neuraminidase. In this paper, the serological properties of agglutinogens developed by proteolytic enzymes (bromelin, ficin, papain, trypsin and pronase) and neuraminidase are investigated by using antisera to trypsin- and neuraminidase-treated red cells. The adsorptions of the antiserum to trypsinized red cells with the cells treated with each of the proteolytic enzymes showed that the agglutinogens uncovered by bromelin, ficin and papain were different from those by pronase and trypsin. It was demonstrated that pronase was the most effective enzyme to uncover the agglutinogen located on deeper site of red cell membrane. This was confirmed by the agglutination with the test cells treated twice with two kinds of the enzymes. The reactions of the antiserum to neuraminidase-treated red cells treated with six kinds of the enzymes indicated that the agglutinogens developed by neuraminidase resembled those by bromelin, ficin and papain more than those by trypsin and pronase.

Agglutinins↗
PubMed1989

Neuraminidase treatment of isolated rat adipocytes and differential regulation of basal and insulin-stimulated glucose transport.

The role of membrane carbohydrate in the function of insulin receptors and glucose transporters was investigated with neuraminidase to release sialic acid from isolated rat adipocytes. Pretreatment of adipocytes with neuraminidase resulted in an increase in basal glucose transport. At the same time, insulin-stimulated glucose transport was reduced by an average of 30%. The enzyme action on glucose transport was not due to a nonspecific membrane perturbation because neuraminidase caused only a nonsignificant decrease in the uptake of the amino acid analog alpha-(methylamino)isobutyric acid and had no effect on basal or insulin-stimulated protein synthesis. Insulin binding was slightly increased in neuraminidase-treated cells, yet the shapes of the dose-response curves for insulin stimulation of glucose transport were similar (EC50 = 0.087 +/- 0.010 and 0.082 +/- 0.008 nM for control and treated cells, respectively). The neuraminidase-induced increase in basal transport was the result of an increase in the affinity of the glucose-transport system (Km = 7.3 +/- 1.4 and 3.6 +/- 0.7 mM before and after treatment, respectively) with no change in Vmax. Conversely, enzyme treatment decreased the Vmax of insulin-stimulated 3-O-methylglucose transport from 87.8 +/- 13.2 to 41.3 +/- 4.9 pmol.2 x 10(5) cells-1.s-1 while not altering the Km. These changes in glucose-transport activity resulting from enzyme treatment were not due to alterations in glucose-transporter concentration on the plasma membrane as measured by the D-glucose-inhibitable binding of [3H]cytochalasin B. Thus, sialic acid plays multiple roles in the control of glucose-transport activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗