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PubMed1987

Effect of syngeneic anti-idiotypic antibody on influenza virus neuraminidase antibody response.

Influenza viruses possess two major surface glycoproteins - hemagglutinin (HA) and neuraminidase (NA). Py203, a monoclonal antibody (Ab) specific for the neuraminidase of the PR8 (H1N1) influenza virus, was used to prepare syngeneic monoclonal anti-idiotypic (anti-Id) Abs. From a BALB/c mouse immunized with Py203 (anti-N1), we obtained RM1, a monoclonal anti-Id Ab. The Py203-Id was detected in a significant fraction of immunoglobulins (Igs) in the primary and secondary responses elicited by PR8 (H1N1) and X31 (H3N2) viruses. In animals injected with minute amounts of RM1 and subsequently boosted with an identical dose of RM1, no detectable anti-NA activity was noted, but a significant increase in Py203-Id-bearing Igs was observed. In the sera of animals injected with minute amounts of RM1 and subsequently boosted with PR8 (H1N1) or X31 (H3N2) viruses, an increase in anti-NA activity and in the level of Py203-Id was noted. Animals injected with large amounts of RM1 and boosted with PR8 and X31 showed a marked suppression of the Py203-Id but no alteration in the anti-NA response. The anti-Id recognizes an idiotope (the Py203 idiotope) shared by antibodies specific for the N1 and N2 neuraminidase variants.

Animals↗
PubMed1999

Cell surface sialic acid and the regulation of immune cell interactions: the neuraminidase effect reconsidered.

It has been known for over a decade that sialidase (neuraminidase) treatment could substantially enhance the capacity of resting B cells to stimulate the proliferation of allogeneic and antigen specific, syngeneic T cells. Thus, cell-surface sialic acid was implicated as a potential modulator of immune cell interaction. However, little progress has been made in either identifying explicit roles for sialic acid in this system or in hypothesizing mechanisms to explain the "neuraminidase effect." Here we show for the first time that cell surface sialic acid on medium incubated B cells blocks access to costimulatory molecules on the B cell surface, and that this is the most likely explanation for the neuraminidase effect. Further, we show that it is likely to be upregulation of ICAM-1 and its subsequent engagement of LFA-1 rather than loss of cell surface sialic acid that in part regulates access to CD86 and other costimulatory molecules. However, we cannot exclude a role for CD86-bound sialic acid on the B cell in modulating binding to T cell CD28. Because sialidase treatment of resting B cells but not resting T cells enables T cell activation, we suggest that sialidase treatment may still be an analogue for an authentic step in B cell activation, and show that for highly activated B cells (activated with polyclonal anti-IgM plus INF-gamma) there is specific loss 2, 6-linked sialic acid. Potential roles for sialic acid in modulating B cell/T cell collaboration are discussed.

Animals↗
PubMed1989

Influence of metronidazole, chloramphenicol, clindamycin and penicillin G on growth and neuraminidase activity of Bacteroides fragilis.

The effects of subinhibitory concentrations of metronidazole, chloramphenicol, clindamycin and penicillin G on cell growth and neuraminidase activity of Bacteroides fragilis were tested in six strains from clinical specimens and two type collection strains. All showed significant inhibition of cell growth at one half the MIC after 24 h incubation. Metronidazole at one quarter the MIC was significantly inhibitory after 24 and 48 h incubation. The neuraminidase activity remained unaltered, in comparison with controls, when metronidazole and clindamycin were tested. Chloramphenicol reduced the enzyme activity at both one half and one quarter the MIC. On the other hand, penicillin G enhanced the neuraminidase activity, although the difference was not statistically significant. These in-vitro effects may simulate the behaviour of the bacteria in abscesses in vivo.

Bacteroides fragilis↗
PubMed2004

Changes in in vitro susceptibility of influenza A H3N2 viruses to a neuraminidase inhibitor drug during evolution in the human host.

OBJECTIVES: Influenza A H3N2 viruses isolated recently have characteristic receptor binding properties that may decrease susceptibility to neuraminidase inhibitor drugs. A panel of clinical isolates and recombinant viruses generated by reverse genetics were characterized and tested for susceptibility to zanamivir. METHODS: Plaque reduction assays and neuraminidase enzyme inhibition assays were used to assess susceptibility to zanamivir. Receptor binding properties of the viruses were characterized by differential agglutination of red blood cells (RBCs) from different species. Sequence analysis of the haemagglutinin (HA) and neuraminidase (NA) genes was carried out. RESULTS: Characterization of a panel of H3N2 clinical isolates from 1968 to 2000 showed a gradual decrease in agglutination of chicken and guinea pig RBCs over time, although all isolates could agglutinate turkey RBCs equally. Sequence analysis of the HA and NA genes identified mutations in conserved residues of the HA1 receptor binding site, in particular Leu-226 --> Ile-226/Val-226, and modification of potential glycosylation site motifs. This may be indicative of changes in virus binding to sialic acid (SA) receptors in recent years. Although recent isolates had reduced susceptibility to zanamivir in MDCK cell based plaque reduction assays, no difference was found in an NA enzyme-inhibition assay. Assays with recombinant isogenic viruses showed that the recent HA, but not the NA, conferred reduced susceptibility to zanamivir. CONCLUSION: This study demonstrates that recent clinical isolates of influenza A H3N2 virus no longer agglutinate chicken RBCs, but despite significant receptor binding changes as a result of changes in HA, there was little variation in sensitivity of the NA to zanamivir.

Animals↗
PubMed1989

Purification and properties of neuraminidase isozymes in Arthrobacter ureafaciens mutant.

An Arthrobacter ureafaciens mutant (M1057) capable of producing neuraminidase constitutively was isolated by NTG mutagenesis from A. ureafaciens KMS 3663. Four molecular species (L, M1, M2, and S) of neuraminidase isozymes were homogeneously purified from the mutant and parent strains by means of DEAE-cellulose, affinity chromatography, ammonium sulfate precipitation, chromatofocusing, and Ultrogel AcA44 gel filtration. The molecular weights of L, M1, M2, and S isozymes were shown to be approximately 88,000, 66,000, 66,000, and 52,000, respectively. The optimal pHs and Km values of these isozymes for N-acetylneuraminosyl-alpha,(2-6)-lactose were 4.5-5.5 and 0.6-0.8 mM. Neuraminidase L, M1, M2, and S were able to hydrolyze oligosaccharides, glycoproteins and gangliosides containing alpha,(2-3)-, alpha,(2-6)-, and alpha,(2-8)-linked N-acetylneuraminic acid. Among these isozymes isolated, isozyme S was most active on colominic acid.

Arthrobacter↗
PubMed1995

Effects of alcohols on the hydrolysis of colominic acid catalyzed by Streptococcus neuraminidase.

Regulation of the activity of neuraminidase of Streptococcus sp. (group K) was evaluated by examining the effects of alcohols on the hydrolysis of colominic acids catalyzed by the neuraminidase. Two kinds of alcohol binding site, activation and inhibition sites, were proposed to exist. Competitive inhibition was observed with alcohols smaller than polyethylene glycol #300 (average molecular weight: 300), so the inhibition site is considered to be the substrate binding site, the size of which was estimated to be 10 A in diameter. On the contrary, polyethylene glycols larger than this size activated the enzyme by 1.5-1.8 times. The activity could be raised by binding of the polyethylene glycols to the activation site. This activation was shown to be due solely to the decrease in the Michaelis constant, Km. The smaller polyethylene glycols (#200 and #300) were also considered to bind to the activation site, although activation was not clearly observed due to compensation with inhibition. Strong substrate inhibition by colominic acid was also observed. The activity of Streptococcus neuraminidase was shown to be regulated intricately by the substrate colominic acid and alcohols contained in the reaction medium.

Alcohols↗
PubMed1997

Single-chain Fv fragments of anti-neuraminidase antibody NC10 containing five- and ten-residue linkers form dimers and with zero-residue linker a trimer.

Single-chain variable fragments (scFvs) of anti-neuraminidase antibody NC10 were constructed by joining the VH and VL domains with 10-residue (Gly4Ser)2 and five-residue (Gly4Ser) linkers; a zero-residue linker scFv was constructed by joining the C-terminal residue of the VH domain to the N-terminus of the VL domain. The scFv with the 10- and five-residue linkers exclusively formed dimeric antibody fragments (M(r) 52000). These were shown to be bivalent and were able to cross-link two neuraminidase tetramers to form a 'sandwich' type complex; each antigen combining site could also bind an anti-idiotype Fab'. The zero-residue linker scFv (M(r) 70000) was shown to form a trimer with three active antigen combining sites, each binding an anti-idiotype Fab' to yield a complex of M(r) 212000. The orientation of the combining sites in the zero-residue linker scFv, however, was such that it could not cross-link tetramers of neuraminidase. BIAcore biosensor experiments showed that the affinity of each individual antigen combining site in both the 10- and five-residue linker scFv dimers and zero-residue linker scFv trimer was essentially the same when the scFvs were immobilized onto the sensor surface. However, when the scFvs were used as the analyte, the dimeric and trimeric scFvs showed an apparent increase in binding affinity due to the avidity of binding the multivalent scFvs.

Amino Acid Sequence↗
PubMed1975

Antitumor immune response following injection of neuraminidase-treated sarcoma cells.

Mice inoculated with MCA-10 sarcoma cells which had previously been incubated with Vibrio cholerae neuraminidase (VCN) demonstrated a significantly lower tumor incidence (9/26) than mice injected with untreated sarcoma cells (10/10) or sarcoma cells incubated with heat-inactivated neuraminidase (28/29) p less than .05. Rechallenge of nontumor-bearing mice from the VCN group with untreated sarcoma cells resulted in a low tumor incidence (4/11), indicating that these mice had developed systemic immunity following the initial injection of VCN-treated tumor cells. These mice also demonstrated significant lymphocytotoxicity against MCA-10 target cells compared with normal control mice (p less than .05). Subsequent cytotoxicity experiments, utilizing groin lymph node and splenic lymphocytes from mice five days following leg injection of VCN-treated, heat-inactivated VCN-treated or untreated MCA-10 cells, demonstrated that the mice injected with VCN-treated tumor cells demonstrated greater antitumor immunity both locally and systemically. This magnification of tumor immunity is postulated as the mechanism by which neuraminidase treated MCA-10 sarcoma cells grew less well in C57 mice than cells incubated with heat-inactivated VCN or cells left untreated.

Animals↗
PubMed1996

Ependymal denudation, aqueductal obliteration and hydrocephalus after a single injection of neuraminidase into the lateral ventricle of adult rats.

To investigate the role of sialic acid in the ependyma of the rat brain, we injected neuraminidase from Clostridium perfingens into the lateral ventricle of 86 adult rats that were sacrificed at various time intervals. After administration of 10 micrograms neuraminidase, ciliated cuboidal ependymal cells of the lateral ventricles, third ventricle, cerebral aqueduct, and the rostral half of the fourth ventricle died and detached. The ependymal regions sealed by tight junctions such as the choroid plexus and the subcommissural organ were not affected. Debris was removed by infiltrating neutrophils and macrophagic cells. At the same time, after ependymal disappearance, the aqueduct was obliterated. In this region, mitoses were evident and cystic ependymal cells were frequent. Hydrocephalus of the lateral and third ventricles was evident 4 days after neuraminidase injection. Gliosis was restricted to the dorsal telencephalic wall of the injected lateral ventricle. It is thought that cleavage of sialic acid from ependymal surface glycoproteins or glycolipids, likely involved in cell adhesion, led to the detaching and death of the ependymal cells. Thereafter, ependymal loss, together with edema, led to fusion of the lateral walls of the cerebral aqueduct and this in turn provoked hydrocephalus of the third and lateral ventricles. This model of experimental hydrocephalus is compared with other models, in particular those of hydrocephalus after viral invasion of the cerebral ventricles.

Age Factors↗
PubMed2005

Viral shedding in children with influenza virus infections treated with neuraminidase inhibitors.

We examined the efficacy of neuraminidase inhibitors for reducing the duration of virus shedding after naturally occurring influenza virus infection. The duration of fever was significantly shorter in patients treated with neuraminidase inhibitors than in untreated patients. The durations of virus shedding from patients treated with neuraminidase inhibitors were not significantly shorter than those of untreated patients.

Acetamides↗
PubMed2001

Rapid diagnostics: the detection of neuraminidase activity as a technology for high-specificity targets.

The accurate detection of influenza by clinical symptoms is challenging since multiple pathogenic viruses and bacteria mimic similar symptoms in a patient. With new and more effective influenza therapeutics available, there is a growing need for highly accurate and rapid diagnosis of influenza, particularly when the window of opportunity for proper treatment is measured in hours. A parallel technology, which is also used in the treatment of influenza, was developed for the rapid diagnosis of influenza by exploiting the enzymatic activity of influenza neuraminidase. This technology, which is called Pathozyme, offers the high specificity inherent from the conservation of the neuraminidase active site. The ZstatFlu test uses a small molecule derivative of sialic acid chemically coupled to a reporter group together with simple point-of-care reagents for directly detecting influenza from a patient specimen with high specificity. A second-generation platform technology using this neuraminidase detection system coupled with a more sensitive chemiluminescent reporter has been developed and formatted for reading on high-speed instant film. This modification resulted in a platform technology many-fold more sensitive than the former while maintaining its inherent high specificity. Preliminary data from a prototype tested during the mild 2000-2001 influenza season demonstrated that an optimized chemiluminescent test system could approach the accuracy of 14 day viral culture in a convenient 10-20 min test. This platform technology is currently being explored for the rapid detection of other pathogenic organisms where sensitivity, specificity and speed are essential in a point-of-care setting.

Amino Acid Sequence↗
PubMed2001

Treatment of influenza with neuraminidase inhibitors: virological implications.

Evaluation of the emergence of influenza virus resistance to neuraminidase inhibitors (NAIs) is now demanded following experience with amantadinamines. Preliminary data have indicated that NAI-resistant virus is unlikely to emerge readily in the clinic and this is consistent with the difficulty experienced in selecting resistant virus in vitro. Resistance mutations can occur in both neuraminidase and haemagglutinin genes. The neuraminidase mutations are viral subtype specific and, therefore, clinically relevant subtypes must be employed for in vitro studies if pre-clinical data are to have predictive value. Haemagglutinin mutations generated in vitro are probably both subtype and cell culture system specific and, therefore, may not be predictive of clinical findings. Analysis of influenza-positive samples from NAI-treated patients in the clinical setting must include samples from late treatment time-points (day 4 and later) in order for resistant virus to be detected as in vitro studies and current clinical experience have indicated that resistant virus is slow to emerge and is transient.

Acetamides↗
PubMed1985

Cytotoxic T cell lysis of target cells fused with liposomes containing influenza virus haemagglutinin and neuraminidase.

The lytic activity of secondary cytotoxic lymphocytes against influenza A virus was tested on cells which had been fused with liposomes containing the haemagglutinin and the neuraminidase of an avian influenza A virus (fowl plague virus, FPV). Fusion was obtained solely by the activity of the haemagglutinin and neuraminidase incorporated into the liposomes, without the need for any additional fusion factor. Highly reproducible lysis of these FPV-liposome target cells by influenza A-specific cytotoxic cells was found. In contrast, target cells containing the glycoproteins HN and F of Newcastle disease virus (NDV) were not lysed. In almost all experiments effector cell populations capable of lysing target cells also lysed the natural killer cell (NK)-sensitive cell line YAC-1. However, high NK activity alone was not sufficient to lyse target cells fused with liposomes containing the viral surface glycoproteins. To our knowledge this is the first report where after artificial introduction of viral surface components into cell membranes (either by fusion or by transfection) lysis of target cells was monitored also for non-specific lysis mediated by NK-like cells. Both the H-2 restriction and the virus specificity of lysis of FPV-liposome target cells indicate that influenza virus haemagglutinin and possibly neuraminidase do function as target antigens for influenza-specific T cells.

Animals↗
PubMed1994

Sialoglycoproteins that bind influenza A virus and resist viral neuraminidase in different animal sera.

Sialoglycoproteins that are resistant to degradation by viral neuraminidase can effectively neutralize influenza A viruses, because they bind irreversibly to the viruses. To detect such proteins in animal sera, we developed an immunochemical assay based on Western blotting techniques. We assessed the binding activity of sialoglycoproteins in sera from nine different animals toward the A/Aichi/2/68 (H3N2) and A/PR/8/34 (H1N1) strains of influenza virus, with or without viral and bacterial neuraminidase treatment. Using this assay, we found that animal sera contain a spectrum of sialoglycoproteins defined by differing abilities to bind influenza A viruses and to resist the viral neuraminidase. Structural analysis of these inhibitors would provide useful information for the development of anti-influenza virus compounds.

Animals↗
PubMed1987

Studies on the Vibrio cholerae mucinase complex. II. Specific neuraminidase activity measured histochemically in a goblet cell assay.

The activity of neuraminidase prepared from the mucinase complex of Vibrio cholerae was measured by a new, semi-quantitative goblet-cell assay. The counts of normal, alcianophilic, sialomucin-containing goblet cells (purple-stained) and neutral mucosubstance-containing goblet cells (magenta-stained) in serial sections of ileum were compared before and after neuraminidase treatment. The procedure provides a more natural assessment of the action of V. cholerae neuraminidase on the viscous intestinal mucus.

Alcian Blue↗
PubMed1992

Unusual diffraction of type B influenza virus neuraminidase crystals.

An unusual X-ray diffraction pattern by tetragonal crystals of a type B influenza virus neuraminidase was observed in that the odd-l reflections were missing or diffuse while the even-l reflections were sharp and strong. A statistical analysis showed that an error (epsilon) in the spacing of successive planes of neuraminidase molecules was randomly distributed along the c direction, which resulted in such an unusual diffraction pattern. The error epsilon follows the Bernoullian distribution and may be caused by a flexible loop on the top surface of the neuraminidase.

Influenza B virus↗
PubMed1983

Interaction between erythroblasts and macrophages in vitro: effect of neuraminidase-treatment of erythroblasts and the role of serum factors.

Some factors influencing the interaction in vitro between dimethylsulphoxide-induced Friend leukaemia erythroblasts (IFLE) and syngeneic mouse peritoneal macrophages (M phi) have been investigated. Desialation of erythroblasts by treatment with neuraminidase resulted in a significant increase in their association with and ingestion by M phi. In addition, the interaction with M phi of both neuraminidase-treated and untreated IFLE was found to be influenced by a heat-stable serum factor. gamma-globulin markedly enhanced the weak IFLE-M phi interaction which occurred at low serum concentration suggesting that the heat-stable factor may be an immunoglobulin. Desialation of the IFLE-rendered them agglutinable by peanut lectin which was used as a probe for neuraminidase-induced membrane changes. By contrast, cycloheximide treatment of IFLE which also enhances their interaction with M phi, did not result in the exposure of receptors for this lectin. It is proposed that both desialation and cycloheximide treatment of IFLE lead to secondary alterations in their membrane structure which renders them recognizable by M phi.

Animals↗
PubMed1976

Studies on the mitogenic activity of trypsin, pronase and neuraminidase on human peripheral blood lymphocytes.

Human peripheral blood lymphocytes were cultured in the presence of protease (trypsin and pronase) and Vibrio choleraneuraminidase. T and B lymphocyte populations were separated and the effect of these enzymes plus phytohaemagglutin or Tuberculin was studied. The results of these experiments show that proteases moderately stimulate spontaneous deoxynucleic acid synthesis of control cells and potentiate the effect of tuberculin on sensitized cells. These enzymes act specifically on B lymphocytes. Neuraminidase also increases spontaneous deoxyribonucleic acid synthesis of control cells and augments significantly the in vitro response to PPD. There is no additive effect of neuraminidase on phytohaemagglutin stimulated cells. Neuraminidase seems to stimulate specifically T lymphocytes. Some possible mechanisms of action of these enzymes are proposed and discussed.

B-Lymphocytes↗