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PubMed1983

Neuraminidase production by a Streptococcus sanguis strain associated with subacute bacterial endocarditis.

The properties of an extracellular neuraminidase produced by a Streptococcus sanguis strain (isolated from a confirmed case of subacute bacterial endocarditis) during growth in a defined medium was examined in this investigation. This enzyme, isolated from concentrated culture supernatants of S. sanguis biotype II, was active against human alpha-1 acid glycoprotein, N-acetylneuramin lactose, bovine submaxillary mucin, and fetuin. Neuraminidase production paralleled bacterial growth in defined medium and was maximal in the early stationary phase of growth but decreased dramatically, probably owing to protease production, during the late stationary phase. The enzyme was purified to near homogeneity by a combination of salt fractionation, ion-exchanged chromatography on DEAE-Sephacel, and gel filtration on Sephadex G-200. These procedures yielded an enzyme preparation that possessed a specific activity of 174.4 mumol of sialic acid released per min per mg of protein against human alpha-1 acid glycoprotein. The Km value for this enzyme with human alpha-1 acid glycoprotein as substrate was 2.5 X 10(-3) M, and the enzyme possessed a pH optimum of 6.5. The S. sanguis neuraminidase had a molecular weight of approximately 85,000 as estimated by gel filtration and approximately 90,000 when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme was stable at temperatures of 4 and 37 degrees C for 3 h, but approximately 50% of the enzymatic activity was lost within 30 min at 50 degrees C, with 100% of the enzymatic activity being destroyed within 10 min at temperatures of greater than or equal to 65 degrees C.

Endocarditis, Subacute Bacterial↗
PubMed1983

Association of neuraminidase-sensitive receptors and putative hydrophobic interactions with high-affinity binding sites for Streptococcus sanguis C5 in salivary pellicles.

The relationship of neuraminidase-sensitive receptors and putative hydrophobic interactions to high- and low-affinity binding sites in experimental salivary pellicles for Streptococcus sanguis C5 was investigated. NaSCN, an inhibitor of hydrophobic interactions, reduced the number of cells which adsorbed to pellicles to a greater extent than NaCl or KCl when both low and high streptococcal concentrations were used in assays. However, NaSCN was not more effective than NaCl or KCl in desorbing 3H-labeled salivary pellicle components from hydroxyapatite, and NaSCN pretreatment of either strain C5 cells or the salivary pellicles did not destroy or remove either the streptococcal adhesions or the pellicle receptors. Neuraminidase treatment of pellicles or the presence of sialic acid-containing gangliosides only inhibited S. sanguis adsorption when low streptococcal concentrations were used. At these concentrations, S. sanguis adsorbs primarily to high-affinity pellicle binding sites. Adsorption isotherms indicated that neuraminidase-sensitive interactions were mainly responsible for the high affinity of these binding sites, whereas putative hydrophobic interactions inhibitable by NaSCN were mainly associated with the numbers of binding sites available. Sugar inhibition studies suggested that the two classes of binding sites previously demonstrated in untreated salivary pellicles for S. sanguis C5 are not the result of a partial conversion of high-affinity sites to low-affinity sites due to removal of sialic acid residues.

Adsorption↗
PubMed1991

Differential expression of Trypanosoma cruzi neuraminidase in intra- and extracellular trypomastigotes.

The developmentally regulated expression of Trypanosoma cruzi neuraminidase in culture cells was monitored by immunofluorescence with a monoclonal antibody (TCN-2) against the enzyme. The results showed that TCN-2 reacted with all intracellular trypomastigote forms (NA+) but not with amastigotes. Immunoprecipitation of radiolabeled neuraminidase confirmed TCN-2 reactivity with trypomastigotes and the specificity of the antibody binding. During exiting from the host cells, all trypomastigotes were still NA+. However, when free in the extracellular environment, the relative proportion of NA+ parasites declined from 100% to about 20%, thereby establishing a subpopulation of trypomastigotes which did not express enzyme (NA-). The expression of neuraminidase in all intracellular trypomastigotes and in only a subpopulation of the extracellular counterpart suggests that the enzyme may play a role in parasite exiting from infected cells.

Animals↗
PubMed1997

A role for pneumolysin but not neuraminidase in the hearing loss and cochlear damage induced by experimental pneumococcal meningitis in guinea pigs.

We investigated the roles of pneumolysin and neuraminidase in the pathogenesis of deafness and cochlear damage during experimental pneumococcal meningitis. Anesthetized guinea pigs were inoculated intracranially with 7.5 log10 CFU of either (i) wild-type Streptococcus pneumoniae D39 (n = 8), (ii) PLN-A, a defined isogenic derivative of D39 deficient in pneumolysin (n = 5), or (iii) deltaNA1, a new derivative of D39 deficient in neuraminidase constructed by insertion-duplication mutagenesis of the nanA gene (n = 5). To quantify hearing loss, the auditory nerve compound action potential evoked by a tone pulse was recorded from the round window membrane of the cochlea every 3 h for 12 h. The organ of Corti was intravitally fixed for subsequent examination by high-resolution scanning and transmission electron microscopy. All animals sustained similar meningeal inflammatory responses. PLN-A induced significantly less hearing loss than D39 over the frequency range of 3 to 10 kHz. Levels of mean hearing loss at 10 kHz 12 h postinoculation were as follows: D39, 50 dB; deltaNA1, 52 dB (P = 0.76 versus D39), and PLN-A, 12 dB (P < 0.0001 versus D39). The mean rates of hearing loss at 10 kHz were 4.4 dB/h for D39, 4.3 dB/h for deltaNA1, and just 1.0 dB/h for PLN-A (P < 0.0001 versus D39). Suppurative labyrinthitis was universal. PLN-A induced the accumulation of less protein in the cerebrospinal fluid (P = 0.04 versus D39). Infection with D39 and deltaNA1 induced significant damage to the reticular lamina, the sensory hair cells, and supporting cells of the organ of Corti. By contrast, after infection with PLN-A, the organ of Corti appeared virtually intact. Pneumolysin seems to be the principal cause of cochlear damage in this model of meningogenic deafness. No clear pathogenic role was demonstrated for neuraminidase.

Animals↗
PubMed1973

Immunity against parainfluenza-3 virus in cattle: anti-neuraminidase activity in serum and nasal secretion.

The antigenicity of two parainfluenza=3 virus strains, a "neuraminidasestrong" and a "neuraminidase-weak," was compared. For both strains the amount of hemagglutinin units was equal. The antibody responses to neuraminidase and hemagglutinin were measured on samples of serum and nasal secretion and were found to be similar, irrespective of the strain used for immunization. Anti-neuraminidase activity was demonstrated in the gel phase of nasal secretion of immunized cattle. Immunglobulin A was found attached to the peplomers of inhibited virus by immuno-electron microscopy.

Administration, Intranasal↗
PubMed1980

Purification and partial characterization of neuraminidase from type III group B streptococci.

Extracellular neuraminidase from a type III fresh clinical isolate of a group B streptococcus was purified by a combination of salt fractionation, affinity chromatography of Affi-Gel blue, ion-exchange chromatography on diethylaminoethylcellulose, and gel filtration on Sephacryl S-200. These procedures yielded enzyme which was purified approximately 1,000-fold compared with the enzyme found in the original supernatant fluid. This type III streptococcal neuraminidase had a molecular weight of approximately 125,000 as estimated by filtration on Sephacryl S-200 and approximately 106,000 when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In contrast to the majority of other bacterial neuraminidases, the type III group B streptococcal enzyme had no effect on colominic acid or N-acetylneuramin-lactose; however, it was quite active on bovine submaxillary mucin.

Chromatography↗
PubMed1967

Neuraminidase of Corynebacterium diphtheriae.

Neuraminidase activity has been found in a variety of strains of Corynebacterium diphtheriae, both toxinogenic and nontoxinogenic. The enzyme has been shown to be intracellular, possibly associated with the cytoplasmic membrane. Toxinogenic strains of the diphtheria bacillus, grown under conditions unsuitable for maximal toxin production, produce neuraminidase, and the enzyme has been purified from cells of the Park Williams no. 8 strain grown under such conditions. Diphtherial toxin and diphtherial neuraminidase have similar molecular weights and remain associated during column chromatography; immunochemically, and in their electrophoretic behavior, they appear distinct.

Buffers↗
PubMed1985

Survey of neuraminidase production by Clostridium butyricum, Clostridium beijerinckii, and Clostridium difficile strains from clinical and nonclinical sources.

Neuraminidase production was investigated in 57 Clostridium butyricum strains, 16 Clostridium beijerinckii strains, and 25 Clostridium difficile strains. Neuraminidase activity was found only in C. butyricum strains originating from one human newborn with neonatal necrotizing enterocolitis, two newborns with hemorrhagic colitis, one infected placenta, and one adult with peritonitis, It was concluded that neuraminidase was not a major virulence factor in C. butyricum strains.

Clostridium↗
PubMed1972

A 2 (N2) neuraminidase of the X-7 influenza virus recombinant: determination of molecular size and subunit composition of the active unit.

Neuraminidase activity of influenza virus was directly seen on sodium dodecyl sulfate polyacrylamide gels with the aid of the synthetic substrate, methoxyphenol neuraminic acid. Neuraminidase (NA) appeared as a high-molecular-weight fraction with a size in the range of 220,000 to 250,000 daltons. Isolation of this fraction from the X-7 strain of influenza virus, dissociation with sodium dodecyl sulfate, and reduction showed the presence of two polypeptides of 66,000 (NA(1)) and 58,000 (NA(2)) molecular weights in equimolar concentration. We postulate that the minimum active unit for the viral A(2) neuraminidase is a tetramer composed of two NA(1) and two NA(2) subunits.

Centrifugation, Density Gradient↗
PubMed1983

Biological consequences of neuraminidase deficiency in Newcastle disease virus.

A second-step revertant (L1) of a temperature-sensitive mutant (C1) of Newcastle disease virus agglutinated erythrocytes normally but had less than 3% of the wild-type (strain AV) levels of neuraminidase activity. Revertant L1 had seven times more virion-associated N-acetylneuraminic acid (NANA) than strain AV. NANA residues on purified virions were specifically labeled with periodate and tritiated borohydride. Analyses of radiolabeled L1 virions on sodium dodecyl sulfate-polyacrylamide gels showed that most of the virion-associated NANA was in a high-molecular-weight component with an electrophoretic mobility different from that of any known viral protein. NANA was also detected in molecules with the electrophoretic mobility of the viral glycoproteins HN and F1. Revertant L1 had a twofold lower rate constant of attachment to HeLa cells than that of the wild-type. Treatment of L1 virions with Vibrio cholerae neuraminidase removed the excess NANA and returned L1 attachment kinetics to normal. Revertant N1, which has 10-fold more neuraminidase activity than L1, penetrated host cells at the same rate as L1. L1 was impaired in elution from erythrocytes. Removal of virion-associated NANA exacerbated this defect. Despite a small disadvantage in attachment and a major defect in elution relative to strain AV, revertant L1 enjoyed a slight advantage over the wild-type during a single reproductive cycle in cultured chicken embryo cells.

Animals↗
PubMed1984

Neutralization of Newcastle disease virus by monoclonal antibodies to the hemagglutinin-neuraminidase glycoprotein: requirement for antibodies to four sites for complete neutralization.

The neutralizing characteristics of monoclonal antibodies directed to four antigenic sites on the hemagglutinin-neuraminidase glycoprotein of Newcastle disease virus were determined. Neutralization by each antibody resulted in a persistent fraction of nonneutralized virus which varied from 1 to 17% depending on the hemagglutinin-neuraminidase site recognized, but not on the antibody. The addition of antibodies to all four sites on the hemagglutinin-neuraminidase glycoprotein was required to give a level of neutralization comparable with that obtained with polyclonal mouse antiserum. The high persistent fractions were not due to viral aggregates, a high level of variants in the virus stock, the use of insufficient antibody, low antibody avidity, or an effect peculiar to the use of the chicken cells as host. The addition of rabbit anti-mouse immunoglobulin to the persistent fraction left by any of the antibodies resulted in a further reduction in infectivity, often by as much as two logs. Thus, some viral particles are capable of binding antibody while retaining their infectivity. The implications of these findings to the mechanism of neutralization are discussed.

Allantois↗
PubMed1985

Hemagglutinin-neuraminidase protein of the paramyxovirus simian virus 5: nucleotide sequence of the mRNA predicts an N-terminal membrane anchor.

The nucleotide sequence of a cloned cDNA copy of the mRNA coding for the hemagglutinin-neuraminidase of the paramyxovirus SV5 was determined. There was a single large open reading frame on the mRNA which encoded a protein of 565 amino acids with a molecular weight of 62,134. The deduced amino acid sequence indicated that the only major hydrophobic region in the protein sufficiently long to anchor the protein in the membrane is located near the N terminus (amino acids 18 to 36). It is suggested that, like the influenza virus neuraminidase, hemagglutinin-neuraminidase of paramyxoviruses is oriented with its N terminus inserted into the membrane.

Amino Acid Sequence↗
PubMed2006

Paramyxovirus receptor-binding molecules: engagement of one site on the hemagglutinin-neuraminidase protein modulates activity at the second site.

The hemagglutinin-neuraminidase (HN) protein of paramyxoviruses carries out three different activities: receptor binding, receptor cleaving (neuraminidase), and triggering of the fusion protein. These three discrete properties each affect the ability of HN to promote viral fusion and entry. For human parainfluenza type 3, one bifunctional site on HN can carry out both binding and neuraminidase, and the receptor mimic, zanamivir, impairs viral entry by blocking receptor binding. We report here that for Newcastle disease virus, the HN receptor avidity is increased by zanamivir, due to activation of a second site that has higher receptor avidity. Only certain receptor mimics effectively activate the second site (site II) via occupation of site I; yet without activation of this second site, binding is mediated entirely by site I. Computational modeling designed to complement the experimental approaches suggests that the potential for small molecule receptor mimics to activate site II, upon binding to site I, directly correlates with their predicted strengths of interaction with site I. Taken together, the experimental and computational data show that the molecules with the strongest interactions with site I-zanamivir and BCX 2798-lead to the activation of site II. The finding that site II, once activated, shows higher avidity for receptor than site I, suggests paradigms for further elucidating the regulation of HN's multiple functions in the viral life cycle.

Antiviral Agents↗
PubMed1987

Neuraminidase deficiency: case report and review of the phenotype.

A 12 year old boy with neuraminidase deficiency (sialidosis, mucolipidosis I) is described. His clinical features included coarse facies, cherry red spot, ataxia, myoclonus, and dysotosis multiplex. The level of neuraminidase activity in cultured fibroblasts was very low and intermediate levels were observed in both parents. The clinical disorders associated with neuraminidase deficiency are reviewed.

Child↗
PubMed1980

The complete neuraminidase of influenza A/PR8/34 (H0N1) is not detectable in its recombinant virus.

The neuraminidase located on the influenza virus recombinant A/Eq (Heq1) x A/PR8 (N1) was relatively a poor antigen (NI titre less than 10) as compared with the enzyme present on the parent virus A/PR8/34 (H0N1) (NI titre 160). This difference in the antigenic behavior of the neuraminidase of A/PR8/34 (H0N1) virus was explored. Results obtained showed that rabbit anti-A/PR8/34 (H0N1) serum contained two distinct types of antineuraminidase antibody and only one type of antineuraminidase antibody was precipitable by the neuraminidase located on the recombinant virus. Evidence suggests that the parent enzyme(s) is not detectable in its entirety on its recombinant virus.

Antigens, Viral↗
PubMed2001

Neuraminidase treatment abrogates the binding abnormality of IgA1 from IgA nephropathy patients and the differential charge distribution of its alpha-heavy chains.

We have studied the interaction of the Gal-GalNAc-reactive champedak lectin-C with neuraminidase-treated and untreated IgA1 from IgA nephropathy patients. The binding ability of the lectin to untreated IgA1 from IgA nephropathy patients was significantly lower as compared to the untreated IgA1 from normal controls. This differential lectin-binding capacity was abrogated when the experiment was performed on neuraminidase-treated sera. Treatment of the serum IgA1 with neuraminidase also abrogated the differential charge distribution between the alpha-heavy chains of IgA nephropathy patients and normal controls.

Adult↗
PubMed1989

Effect of neuraminidase on the adherence to salivary pellicle of Streptococcus sanguis and Streptococcus mitis.

Neuraminidase-sensitive adherence to experimental salivary pellicles was studied using eight strains of Streptococcus sanguis and five strains of Streptococcus mitis. Approximately 60% of the strains of each species showed significantly lower adherence to neuraminidase-treated versus untreated saliva-coated hydroxyapatite. In addition, the adherence of several of these streptococcal strains to saliva-coated hydroxyapatite and neuraminidase-treated saliva-coated hydroxyapatite was inhibited using galactose and N-acetyl-D-galactosamine. Results from these studies suggested that several salivary receptors mediate adherence of these species.

Acetylgalactosamine↗