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PubMed1979

Biochemical properties of paramyxovirus Duck/Mississippi/75 neuraminidase.

The neuraminidase activity of two strains of Duck/Mississippi/75 virus:DK/Mississippi/320 and DK/Mississippi/334 was studied. These neuraminidases hydrolyse the alpha 2 leads to 3 and alpha 2 leads to 8 ketosidic bonds of different substrates such as fetuin, N-acetyl neuramine lactose and colominic acid, but do not hydrolyse the alpha 2 leads to 6 bonds of mucin type I and type II. The kinetic values of the neuraminidases, Michaelis constant, maximal and initial velocities and the effect of pH, temperature and detergents were also evaluated. The isolates differ mainly in the optimal pH and temperature conditions of activity. As with other paramyxovirus neuraminidases, the enzyme of DK/Mississippi/75 was destroyed by ionic but not non-ionic detergents.

Animals↗
PubMed1975

Preparation of a glycoprotein fraction from pooled human plasma and its evaluation as a substrate for the assay of Clostridium welchii (C. perfringens) neuraminidase.

A glycoprotein fraction (fraction VII) suitable for use as a substrate in assays of microbial neuraminidase was prepared from pooled human plasma. It is pasteurised during preparation to eliminate the risk of transmission of serum hepatitis. This results in polymerisation of some of the gamma1-acid glycoprotein, but fraction VII is shown to be an excellent substrate for the neuraminidase of Clostridium welchii (C. perfringens). A sensitive assay procedure is described. A number of factors may interfere with the measurement of NANA released by the action of microbial neuraminidase and procedures are described for evaluation of this problem. Fraction VII is easy to prepare, cheap and available in standard form in large amounts (inquiries should be addressed to J. K. S.); it is recommended for routine use as a convenient substrate for neuraminidase assays.

Clostridium perfringens↗
PubMed1987

Enzymological characteristics of avian influenza A virus neuraminidase.

Neuraminidases of 18 strains of avian influenza A virus were examined by both colorimetric and fluorometric assays using fetuin and 4-methylumbelliferyl-N-Ac-alpha-D-neuraminide as substrates, respectively, to compare them with those of human influenza A and B viruses. The ratios of the neuraminidase activity of avian influenza virus measured by the colorimetric assay method to that measured by the fluorometric assay were distributed in the range of 2.4-20.3. The enzyme of avian influenza virus showed calcium-ion dependence in both assay methods. These results suggest that neuraminidase of avian influenza A virus is varies greatly from one strain to another in substrate specificity as compared with those of human influenza A and B viruses, and that some strains of avian influenza A virus have a neuraminidase with unique enzymological characteristics different from that of human influenza A virus as well as that of influenza B virus.

Colorimetry↗
PubMed1989

Influenza A virus enhances allergic histamine release. Effect of neuraminidase.

Histamine release was examined in leukocyte suspensions from patients allergic to house dust mite, grass pollen, birch pollen or cat dander. Influenza A virus was found to enhance the antigen-induced mediator release, but did not cause release of histamine from the cells per se. Also histamine release induced by anti-IgE in cell suspensions from normal individuals was enhanced by virus. The potentiating effect of influenza A virus might be due to neuraminidase on the surface of virus, since a similar effect was caused by a purified neuraminidase obtained from Vibrio cholerae, and the effect of virus as well as the neuraminidase was completely abolished by a potent neuraminidase inhibitor. The synergistic enhancement in IgE-mediated histamine release by virus could be of significance for the conversion from latent to manifest asthma.

Adult↗
PubMed1981

Changes in particulate neuraminidase activity during normal and staggerer mutant mouse development.

The activity of particulate neuraminidase (sialidase, EC 3.2.1.18) in wild-type mice and the neurological mutant Staggerer was studied during development. Peak activity of this enzyme was observed at postnatal day 3 (P3) in three tissues of normal mice: cerebellum, cerebrum, and liver. In Staggerer, however, neuraminidase peak activity was observed at P27 in the cerebellum, whereas the activity was close to normal in Staggerer cerebrum and liver. Activities of the other glycosidases in Staggerer (alpha-glucosidase (pH 3.7), alpha-glucosidase (pH 6.0), N-acetyl-beta-hexosaminidase, beta-glucosidase, and beta-galactosidase) did not show significant variation compared with wild-type at P27 in any of the three tissues. This indicates that the late activity peak of particulate neuraminidase activity in the Staggerer cerebellum is neuraminidase-specific and not due to a general increase of lysosomal enzymes.

Aging↗
PubMed1992

Role of myelin-associated neuraminidase in the ganglioside metabolism of rat brain myelin.

The role of myelin-associated neuraminidase in ganglioside metabolism was examined using rats of ages ranging from 17 to 97 days. The neuraminidase activity directed toward the ganglioside GM3 in the total myelin fraction was high during the period of active myelination and, thereafter, decreased rapidly to the adult level. The ganglioside composition became simpler during development with an increasing amount of GM1 and decreasing percentages of di- and polysialogangliosides. The decrease in the proportion of GD1a was most prominent, whereas relative amounts of GD1b and GT1b increased transiently before reducing to the adult levels. The heavy myelin subfraction contained higher percentages of di- and polysialo-species compared to the light myelin fraction at young and adult ages. The in vitro incubation of myelin of young rats under an optimal condition for neuraminidase action produced a profile of ganglioside changes similar to that observed in in vivo development. These results strongly suggest that myelin-associated neuraminidase may play a pivotal role in the developmental changes in the ganglioside composition of rat brain myelin.

Aging↗
PubMed1986

Inotropic effects of Ca2+ channel agonist and antagonists in neuraminidase-treated left atria of rats.

The effects of removal of sialic acid from cardiac sarcolemma on contractile functions and on inotropic responses to Ca2+ channel agonist and antagonists were investigated in rat left atria. About 64% of the total sialic acid content of the left atria was removed during a 90 min exposure to neuraminidase (2 u ml-1). The removal of sialic acid neither affected the development of twitch tension induced by stimulation at a frequency of 0.5 Hz, nor altered the interval-dependent changes in contractility such as the force-frequency relationship and post rest contractions. The positive inotropic effects produced by isoprenaline, and by an increase in extracellular Ca2+ concentration were the same in the neuraminidase-treated preparations as those in the untreated preparations. Bay K 8644, a Ca2+ channel agonist, induced an increase in contractility in the neuraminidase-treated preparations comparable to that in the untreated ones. Neuraminidase treatment significantly attenuated the negative inotropic effects of verapamil and diltiazem, whereas it had no effect on that of nifedipine. The results indicate that sialic acid removal modifies neither the basal contractile functions nor the positive inotropism which is associated with an enhancement of the slow inward Ca2+ current. However, sialic acid, which constitutes the glycocalyx of the cardiac sarcolemma, may be involved in the mechanism of the Ca2+ channel antagonistic actions of verapamil and diltiazem, but not that of nifedipine. Thus, our results provide pharmacological evidence that verapamil and diltiazem behave differently from the dihydropyridine compounds.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1972

Coupled-enzyme system for measuring viral neuraminidase activity.

A coupled-enzyme assay for determining viral neuraminidase activity is described. All reactants-viral neuraminidase, the initial substrate (fetuin), N-acetylneuraminic acid aldolase, lactic acid dehydrogenase, and reduced nicotinamide adenine dinucleotide-are combined in a single cuvette. Thus, in a single coupled system neuraminidase releases N-acetylneuraminic acid, which is cleaved to N-acetyl-D-mannosamine and pyruvic acid; finally, pyruvate is reduced to lactate as reduced nicotinamide adenine dinucleotide is oxidized. The rate of change of absorbance at 340 nm, as reduced nicotinamide adenine dinucleotide is oxidized, is a measure of the rate of reaction of the coupled system. This procedure, which measures the rate of release of N-acetylneuraminic acid by neuraminidase, is an alternate method for those procedures which require multistep, colorimetric determinations.

Alpha-Globulins↗
PubMed1973

Applications of a synthetic neuraminidase substrate.

A rapid and precise assay for neuraminidase using 2-(3'-methoxyphenyl)-N-acetyl-alpha-neuraminic acid (MPN) is described. It is proposed that this substrate be used for the standardization of activity of neuraminidases from viral, bacterial, and mammalian sources. MPN is also used as a chromogenic substrate to localize influenza and parainfluenza virus foci in tissue culture. This technique permits the recovery of infective virus from these stained "plaques." It has also been demonstrated that immunoprecipitin lines containing neuraminidase complexes with antibody in the Ouchterlony test can be observed by a similar staining procedure. No enzyme inhibition occurs in the presence of anti-neuraminidase antibodies or concanavalin A when MPN is used as a substrate in contrast to the results with high-molecular-weight substrates such as fetuin.

Animals↗
PubMed1976

Measurement of antibody to influenza virus neuraminidase by single radial hemolysis in agarose gels.

A simple method of assaying anti-influenza neuraminidase antibodies in human sera was described. Suitable antigenic hybrid viruses were adsorbed to sheep erythrocytes, which were then incorporated into agarose gels. When sera were introduced into wells cut in the gels, zones of hemolysis were observed in the neighborhood of those containing neuraminidase antibodies. There was a direct relationship between zone size and antibody titer. No purification of adsorbed viruses was necessary. The test was rapid, required very simple reagents, gave results that agreed well with those given by conventional techniques, and appeared to be the most sensitive of four methods evaluated. Studies of cross-reactions by hyperimmune sera against homologous and heterologous neuraminidases and of absorption of neuraminidase antibodies from human sera indicated a high degree of specificity. The technique seems to be suitable for large-scale epidemiological investigations.

Antibodies, Viral↗
PubMed1983

Measurement of antibodies to influenza virus neuraminidase by an enzyme-linked immunosorbent assay.

The contribution of influenza A neuraminidase antibodies to the reaction with whole virus in an enzyme-linked immunosorbent assay (ELISA) was assessed by specific absorption of rabbit hyperimmune sera. Although measurable and independent, the effect of neuraminidase antibodies was less than that of hemagglutinin antibodies. Recombinants with an irrelevant hemagglutinin were used successfully as antigens in an ELISA test for measuring neuraminidase antibodies in rabbit hyperimmune sera, but a low cross-reaction between N1 and N2 subtypes was observed. However, for the measurement of N2 antibody rises in human sera, ELISA was highly specific and compared favorably with two other methods, neuraminidase inhibition and single radial hemolysis.

Absorption↗
PubMed1984

Neuraminidase production by Vibrio cholerae O1 and other diarrheagenic bacteria.

Vibrio cholerae O1 strains belonging to both biotypes (classical and El Tor) and both serotypes (Ogawa and Inaba) produced neuraminidase which was released rather than cell bound. Classical strains made more neuraminidase than did El Tor strains. About one-third of V. cholerae non-O1 strains and one-fourth of Aeromonas hydrophila strains were neuraminidase positive. Strains of enterotoxigenic Escherichia coli, Vibrio parahaemolyticus, and Shigella spp. did not produce detectable neuraminidase.

Diarrhea↗
PubMed1993

A role for Bacteroides fragilis neuraminidase in bacterial growth in two model systems.

Two Bacteroides fragilis neuraminidase-deficient mutants were used to study the role of neuraminidase activity in growth of B. fragilis in tissue culture monolayers (CHO cells) and in the in vivo rat granuloma pouch. The nanH structural gene for neuraminidase was cloned from B. fragilis TM4000 and was used to create two isogenic strains with chromosomal disruptions at the nanH gene. B. fragilis VRC404 contains an insertion flanked by disrupted copies of the nanH gene, and B. fragilis VRC426 contains a deletion of a significant portion of nanH coding sequences. The insertion mutant VRC404 is capable of reverting to nanH+. It grew as well as the wild type in CHO monolayers. However, between 48 and 72 h after infection, the bacterial population was enriched with nanH+ bacterial cells (10 to 20%). In the rat pouch 48 h after infection, more than 90% of the population sampled had become nanH+. The deletion mutant VRC426 showed a severe growth defect in the rat pouch model. In addition, VRC426 was efficiently outgrown by the wild type in competition experiments, even when the mutant was present at 10 times the number of wild-type cells at the time of infection. A common characteristic of both model systems is a drastic decrease in the free glucose concentration 16 to 24 h postinfection. We suggest that neuraminidase activity may be required for B. fragilis to grow to maximal levels in the tissue culture and rat pouch systems by making other carbon sources available after glucose levels are reduced.

Animals↗
PubMed2000

Evaluation of the virulence of a Streptococcus pneumoniae neuraminidase-deficient mutant in nasopharyngeal colonization and development of otitis media in the chinchilla model.

Considerable evidence has implicated Streptococcus pneumoniae neuraminidase in the pathogenesis of otitis media (OM); however, its exact role has not been conclusively established. Recently, an S. pneumoniae neuraminidase-deficient mutant, DeltaNA1, has been constructed by insertion-duplication mutagenesis of the nanA gene of S. pneumoniae strain D39. The relative ability of DeltaNA1 and the D39 parent strain to colonize the nasopharynx and to induce OM subsequent to intranasal inoculation and to survive in the middle ear cleft after direct challenge of the middle ear were evaluated in the chinchilla model. Nasopharyngeal colonization data indicate a significant difference in the ability of the DeltaNA1 mutant to colonize as well as to persist in the nasopharynx. The neuraminidase-deficient mutant was eliminated from the nasopharynx 2 weeks earlier than the D39 parent strain. Both the parent and the mutant exhibited similar virulence levels and kinetics during the first week after direct inoculation of the middle ear. The DeltaNA1 neuraminidase-deficient mutant, however, was then completely eliminated from the middle ear by day 10 postchallenge, 11 days before the D39 parent strain. Data from this study indicate that products of the nanA gene have an impact on the ability of S. pneumoniae to colonize and persist in the nasopharynx as well as the middle ear.

Animals↗
PubMed1973

Occurrence of neuraminidase and acylneuraminate pyruvate lyase in a strain of vibrio falling into Heiberg's group II isolated from a patient with diarrhea.

The enzymes neuraminidase (EC 3.2.1.18) and acylneuraminate pyruvate lyase (EC 4.1.3.3) were found in a strain of vibrio falling into Heiberg's group II isolated from a patient with diarrhea. The neuraminidase of this strain resembles the neuraminidase of Vibrio cholerae. The pH-optimum, activation by Ca-ions and heat inactivation were studied. There is also some indication of an immunologically common antigenicity. The occurrence of this neuraminidase in the Heiberg's group II vibrio stain is discussed especially with reference to the relationship with the well known enzyme of Vibrio cholerae.

Calcium↗
PubMed1974

Neuraminidase activity in Streptococcus sanguis and in the viridans group, and occurrence of acylneuraminate lyase in viridans organisms isolated from patients with septicemia.

The enzyme neuraminidase (EC 3.2.1.18) was found to be strongly active in different types of Streptococcus sanguis and S. viridans, and, in addition, the occurrence of the enzyme acylneuraminate pyruvate lyase (EC 4.1.3.3) was described in S. viridans. The enzyme-active bacteria strains were isolated from blood cultures of patients with septicemia. Whereas S. sanguis lost its strong neuraminidase activity after some weeks, S. viridans retained its enzyme activity for a long time in culture. Immunoelectrophoretic studies of the blood cultures of patients with streptococcal infections showed the loss of neuraminic acid in most glycoproteins of the serum, proving the in vivo action of neuraminidase. The pathogenic role of neuraminidase is discussed in streptococcal septicemia from the viewpoint of present knowledge.

Chromatography, Paper↗
PubMed1978

Induction and regulation of neuraminidase synthesis in Arthrobacter sialophilus.

A variety of N-acetylneuraminic acid (AcNeu) derivatives and analogs were examined as inducers of the extracellular neuraminidase of Arthrobacter sialophilus. Neuraminidase inductions were primarily studied with tryptone-yeast extract-grown cells after washing and resuspension in a defined replacement medium. The addition of readily metabolizable carbon sources to the latter, such as 0.1% casein hydrolysate, glutamate, or glucose, enhanced enzyme synthesis. Enzyme appearance occurred after a lag in the uptake of inducers, suggesting the participation of a co-inducible transport system. Neuraminidase formation during exponential growth in the presence of AcNeu ceased after depletion of this end product from the medium. It was found, besides AcNeu, that its methyl ester, 2-deoxy-2,3-dehydro-N-acetylneuraminic acid and 2-deoxy-2,3-dehydro-N-acetyl-neuraminic acid methyl ester are each active inducers, whereas beta-anomers of AcNeu-ketosides are not. These results, in comparison to known enzyme specificity, have revealed significant differences and parallels between the inductive and catalytic processes for neuraminidase. In particular, it would appear that the free carboxylate and oxygenation at C-2 of AcNeu, essential for enzyme catalysis with traditional AcNeu substrates, are not necessary for induction and, furthermore, that transition state analogs can specifically induce this enzyme. The failure to observe catabolite repression in this system is discussed in relation to the intermediary metabolism of the genus Arthrobacter.

Arthrobacter↗
PubMed1996

Cloning and characterization of nanB, a second Streptococcus pneumoniae neuraminidase gene, and purification of the NanB enzyme from recombinant Escherichia coli.

Streptococcus pneumoniae is believed to produce more than one form of neuraminidase, but there has been uncertainty as to whether this is due to posttranslational modification of a single gene product or the existence of more than one neuraminidase-encoding gene. Only one stable pneumococcal neuraminidase gene (designated nanA) has been described. In the present study, we isolated and characterized a second neuraminidase gene (designated nanB), which is located close to nanA on the pneumococcal chromosome (approximately 4.5kb downstream). nanB was located on an operon separate from that of nanA, which includes at least five other open reading frames. NanB has a predicted size of 74.5 kDa after cleavage of a 29-amino-acid signal peptide. There was negligible amino acid homology between NanA and NanB, but NanB did exhibit limited homology with the sialidase of Clostridium septicum. NanB was purified from recombinant Escherichia coli and found to have a pH optimum of 4.5, compared with 6.5 to 7.0 for NanA. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis suggested that NanB has a molecular size of approximately 65 kDa. The discrepancy between this estimate and the size predicted from the nucleotide sequence is most likely a consequence of C-terminal processing or anomalous electrophoretic behavior.

Amino Acid Sequence↗