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PubMed1969

The antigenic relationship of the neuraminidase of Hong Kong virus to that of other human strains of influenza A virus.

Segregation of the haemagglutinin and neuraminidase antigens of 6 representative influenza A2 viruses and the Hong Kong virus by genetic recombination permitted a precise analysis of the antigenic constitution of each virus. Although cross-reactivity of the Hong Kong influenza virus and all 6 influenza A2 strains was demonstrated, the cross-reactivity was shown to be entirely dependent upon and mediated through the viral neuraminidase and not the haemagglutinin. The neuraminidase of the Hong Kong virus is slightly reactive with the neuraminidase of older A2 strains but is apparently identical to the enzyme of the recent (1967-68) variants.

Antigens↗
PubMedDate not supplied

Toxicological studies with therapeutically-applicable Vibrio cholerae neuraminidase.

Neuraminidase was submitted to a preclinical toxicological investigation in short--and long--term experiments. The acute toxicity in mice, rats, and guinea pigs is low (LD 50 i.v.: mouse 30,000 units/kg, rat 44,000 units/kg, guinea pig 7,700 units/kg; s.c.: mouse, rat, guinea pig more than 30,000 u/kg). After i.v. injection into dogs, respiration is not at all and blood pressure only slightly altered. Neuraminidase is pyrogenfree in the rabbit test. Assays of antigenicity in guinea pigs and tests on local i.v., i.m., s.c. toxicity in rabbits and guinea pigs showed only moderate toxic signs. Chronicity studies were performed in dogs and rats over 90 days with repeated administration of various amounts of Neuraminidase (dogs 50-2,000 u/kg, rats 500-2,000 u/kg i.v., 26 or 65 injections). Only in very high dose levels (more than 500 u/kg) Neuraminidase was toxic in dogs (damage of liver, kidney and erythrocytes). In lower doses in dogs and in rats the clinical, biochemical, and hematological data as well as urinalysis and anatomopathological results give no evidence of systemic or important alterations which would preclude the clinical investigation of the drug.

Animals↗
PubMed1980

[Use of the aggregate hemagglutination method for determining cholera vibrio neuraminidase].

The suitability of the aggregate hemagglutination test for neuraminidase determination in biological fluids has been evaluated. This test allows one to determine neuraminidase at a concentration of 2--4 mg/ml. The sensitivity of this test is more than 2 orders higher than that of gel diffusion technique and the thiobarbituric assay. The test has revealed that neuraminidase produced by Vibrio cholerae is not immunologically related to other kinds of neuraminidase produced by Corynebacterium diphtheriae, Clostridium perfringes and Erysepelothrix insidiosa.

Antigens, Bacterial↗
PubMed1984

Extracellular neuraminidase production of streptococci associated with acute nephritis.

The possibility that streptococcal neuraminidase has a pathogenic role in acute poststreptococcal glomerulonephritis is reviewed. Experimental and clinical evidence suggesting autologous immune phenomena and anti-Ig reactivity in this disease is discussed. Neuraminidase may also induce sialic acid depletion that would be expected to result in changes of the electrical charge in the immune complex as well as in the glomerular polyanion filtration barrier. The nature of these changes will facilitate penetrability of material with nephritogenic potential. Neuraminidase production was detected in the majority of streptococcal isolates obtained from patients with glomerulonephritis and the best substrate for screening purposes appears to be bovine submaxillary gland mucin. On the basis of available evidence, it is suggested that the development of glomerulonephritis after streptococcal infection probably does not depend on neuraminidase production by the bacteria; however, this enzyme may be responsible for the anti-Ig reactivity demonstrated in some patients and thereby influence the course of the disease.

Acute Disease↗
PubMed1981

Neuraminidase production by Propionibacterium acnes-strains isolated from patients with acne vulgaris, seborrheic eczema and healthy subjects.

Among cutaneous propionibacteria, synthesis of neuraminidase is highest in strains of the species P, acnes. In the present study, neuraminidase activity was discovered in 90.0% of P. acnes strains isolated from acne lesions compared with 72.7% of strains from normal human skin. Neuraminidase-positive strains from acne lesions, moreover, produced statistically significant higher amounts of the enzyme (X = 727 microunits/ml bacterial suspension) than isolates from normal skin (X - 392 microunits/ml). Whereas the moderate production of neuraminidase by strains from patients with seborrheic eczema is probably of no causative importance, the enzyme has to be discussed a potential etiologic factor in acne vulgaris.

Acne Vulgaris↗
PubMed1984

Effects of neuraminidase on the regulation of erythropoiesis.

In this article, we present evidence that sialic acid-containing surface components play a role in the regulation of erythropoiesis. A 1-hr exposure of mouse bone marrow cells to high concentrations of neuraminidase reduced erythroid colony formation. Coculture of 10(6) untreated thymocytes with neuraminidase-treated bone marrow cells restored erythroid colony growth. Neuraminidase-treated thymocytes retained their ability to suppress erythroid colony formation by untreated marrow cells, but lost their ability to enhance erythroid colony formation. Continuous exposure to low concentrations of neuraminidase enhanced erythroid bone marrow cell colony growth in response to a suboptimal dose of erythropoietin.

Animals↗
PubMed1983

A neuraminidase from Streptococcus sanguis that can release O-acetylated sialic acids.

The naturally occurring sialic acids can have different types of N- and O-substitutions, resulting in more than 20 known isomers and compounds. Most methods for the detailed study of these various sialic acids require that the molecules be first released from their alpha-glycosidic linkage. When mild acid hydrolysis is used for this purpose, significant destruction of O-substituent groups occur. On the other hand, the presence of O-substituent groups renders the sialic acid molecule partially or completely resistant to the action of the currently known neuraminidase. To circumvent this problem, we searched for a neuraminidase whose activity is not affected by O-substitution. We reasoned that because Streptococcus sanguis from the human oral cavity is continually exposed to O-substituted sialic acids, its extracellular neuraminidase might not be blocked by O-substitution. We therefore purified this enzyme 3100-fold (56% yield) using ammonium sulfate precipitation, N-(p-aminophenyl)oxamic acid-agarose affinity chromatography, and chromatography on quaternary aminoethyl (QAE)-Sephadex, sulfopropyl (SP)-Sephadex, and Sephacryl S-200. The purified preparation is free of other significant glycosidase activities and proteolytic activities. It is capable of quantitatively releasing all the O-acetylated sialic acids that we studied with the single exception of the 4-O-acetylated sialic acid of equine submaxillary mucin. The activity of the enzyme is also not restricted by the type pf sialic acid linkage or the nature of the underlying oligosaccharide. However, it has maximal activity on gangliosides only in the presence of detergents. The general properties of this enzyme are described and its substrate specificities are contrasted with those of the commonly used neuraminidase from Vibrio cholerae.

Animals↗
PubMedDate not supplied

Extracellular neuraminidase production by a strain of Pseudomonas aeruginosa isolated from cystic fibrosis.

Extracellular neuraminidase production was found in a strain of Pseudomonas aeruginosa isolated from a patient with cystic fibrosis. Extracellular neuraminidase was secreted in growth medium during the early stationary phase. The enzyme was produced in brain-heart infusion supplemented with 10% colt serum. The enzyme hydrolyzed the alpha 2 leads to 3 glycosidic linkages from N-acetylneuraminlactose and fetuin, and cleaved also mucins from CF. Activity was optimal pH 6.6-7.0, not modified by addition of calcium and magnesium cations, and insensitive to EDTA inhibition (50% inhibition in the presence of 0.035 mM EDTA). The enzyme was stable at temperatures of 4 degrees C for weeks and 37 degrees C for at least 24 h but was almost completely inactivated within 30 min at 56 degrees C. No N-acetylneuraminic acid aldolase was secreted in growth medium. For the neuraminidase producing strain and non-producing reference strains for P. aeruginosa, we demonstrated an endogeneous neuraminidase acting on endogenous substrate from highly concentrated cell extracts.

Child↗
PubMed1982

A B-lymphoma cell line that forms rosettes with neuraminidase-treated sheep erythrocytes through monoclonal surface immunoglobulin.

Undifferentiated lymphoma from a 39-year-old female became serially xenotransplantable to preirradiated nude mice. The tumor cells (KT) possessed a monoclonal surface immunoglobulin (SIg mu, kappa) and formed rosettes with neuraminidase-treated sheep erythrocytes (SEn). Precise characterizations of the SEn rosette, however, revealed the following facts: (1) Neuraminidase-untreated or 2-aminoethylisothiuronium bromide (AET) treated sheep erythrocytes were not bound to the KT cells. (2) SEn rosettes on the KT cells did not show a temperature dependency. (3) Neuraminidase-treated erythrocytes from man, horse, mouse, and rabbit were not bound to the KT cells. (4) Preincubation of the KT cells with antipolyvalent immunoglobulin or anti-kappa-chain serum abolished the SEn rosette formation. (5) Trypsinization decreased both SEn rosettes and SIg on the KT cells. (6) SEn rosettes on the KT cells were too loose to be separated from nonrosetting cells by a Percoll gradient centrifugation method. Summarizing these results, the monoclonal SIg on the KT cells recognized sheep erythrocyte antigen(s) that were exposed only after the neuraminidase treatment. Therefore, this was considered to be a case with peculiar B-lymphoma cells that bound SEn through their SIg.

Adult↗
PubMed1982

Substrate and product specificity of Arthrobacter sialophilus neuraminidase.

Arthrobacter sialophilus neuraminidase catalyzes the hydrolysis of N-acetylneuraminyl-alpha-oxygen, nitrogen, and azido glycosides. The most effective of those substrates examined was N-acetylneuraminyl-alpha-4-methylumbelliferylglycoside (AcNeu-alpha-4-MU; Km app, 0.0193 mM; kcat, 136.4 sec-1). The products resulting from the enzymic hydrolysis of N-acetylneuraminyl-alpha-azido-glycoside were N-acetylneuraminic acid and azide ion. N-acetylneuraminyl-alpha-2,3-thiogalactylglycoside and N-acetylneuraminyl-alpha-2,6-thiogalactylglycoside were competitive inhibitors of the enzyme having KI values of 1.52 mM and 1.70 mM, respectively. Dissociation constants for these thioglycosides were also determined by fluorescence enzyme titrations which gave values similar to those determined kinetically. N-Acetylneuraminic acid, but not its methyl ester, was a competitive inhibitor of neuraminidase. Its KI value, 0.18 mM, was also determined by both methods. 5-Acetamido-2,6-anhydro-3,5-dideoxy-D-glycero-D-talo-nonulosonic acid (2-deoxy-4-epi-AcNeu) was found to be a weak competitive inhibitor (KI, 12.1 mM). A. sialophilus neuraminidase further catalyzes transglycosidation reactions with methanol as acceptor. Methanol had no effect on the release of 4-MU by enzymatic hydrolysis of AcNeu-alpha-4-MU, suggesting that the formation of the enzyme-glycone intermediate is the rate-determining step. The anomeric configuration of the product of this reaction, as shown by 13C-nmr spectroscopy, is N-acetylneuraminyl-alpha-methylglycoside. Neuraminidase, therefore, catalyzes its reactions with overall retention of configuration.

Arthrobacter↗
PubMedDate not supplied

[Isolation of preparative amounts of influenza virus neuraminidase by affinity chromatography].

Synthesis of neuraminidase activity in an affinity column with an inhibitor para-amino-phenyloxamine acid (PAPOA), immobilized on sepharose via tripeptide "spacer" (glycyl-glycyl-tyrosine) is described as well as the conditions of PAPOA synthesis. The column has been tested for isolation of neuraminidase types N1 and N2 from various influenza virus strains. The strain specificity of the action of the column in neuraminidase isolation was demonstrated. Neuraminidase free from admixtures has been isolated from the A/PR8/34, A/FM/1/47 and recombinant X-7 strains.

Chromatography, Affinity↗
PubMed1982

Hemolysis and fusion by influenza viruses with heat-inactivated neuraminidase activity.

Influenza virus hemolytic activity was found to be more heat-resistant than neuraminidase activity, and to be heat-inactivated similarly to hemagglutination activity, in sharp contrast to the case with paramyxoviruses, where the hemolytic activity is the most heat-labile, and hemagglutination and neuraminidase activities are inactivated similarly by heat. Influenza viruses with heat-inactivated neuraminidase activity, which still showed hemagglutination and hemolytic activities, were found to be able to induce cell fusion and envelope fusion. This finding suggested that the hemolytic and fusion activities are not dependent on neuraminidase activity. The hemolytic activity was largely inhibited by anti-hemagglutinin serum of the same subtype. The pH range, heat stability, and antiserum susceptibility of the hemolytic activity were found to be independent of the cells in which the virus was grown.

Allantoin↗
PubMed1982

[Neuraminidase of influenza virus].

Neuraminidase or sialidase (EC 3.2.1.18, acylneuraminyl hydrolase) from a strain of the influenza virus A (H3N2), identical to the A/Hong Kong/68 (H3N2) strain, has been purified and characterized by electrofocusing; only about 20% of the previous enzymic activity was lost after electrofocusing. The enzyme activity was measured by the peryodate-thiobarbiturate procedure, by the methoxyphenol-antipyrine method, and by spectrophotometry at 340 nm of the NADH produced in the oxidation of the beta-galactose + NAD+; this beta-galactose was released from lactose by beta-galactosidase; and lactose was liberated from N-acetylneuraminyl-lactose by the neuraminidase activity. The results of the interference by some chemical compounds, which are not true inhibitory agents for the enzyme, on the peryodate-thiobarbiturate reaction are indicated, as well as the detection of other compounds which are true inhibitors of this enzyme in vitro. This neuraminidase was able to release sialic acid with linkages alpha 2-3, alpha 2-6 and alpha 2-8 from several substrates, but with very different efficiency. Natural substrates such as the oligosaccharide N-acetylneuraminyl-lactose, glycoproteins (fetuin, bovine horse brain, colominic acid, and synthetic substrates such as 5-N-acetyl-2-O-(3-methoxyphenyl)-alpha-D-neuraminic acid and 2'-(4-methyl umbellyferil)-alpha-D-N-acetylneuraminic acid were hydrolyzed by this enzyme. Finally, the finding of neuraminidase in ovine, equine and porcine platelet is summarized.

Animals↗
PubMed1982

[Effect of low pH values on the infectivity and neuraminidase activity of human and animal strains of influenza virus type A].

The influence of acidic pH on the infectivity and neuraminidase activity of human, equine and avian type A influenza virus strains has been studied. Following exposure to pH 3 human and equine strains lost their infectivity completely, whereas all investigated strains of the subtypes Hav6N2 and Hav7Neq2 retained a certain amount of infectivity. In contrast to human and equine strains the avian strains retained also 38% of their original neuraminidase activity after acidic treatment. Partial retention of infectivity and the relative stability of the neuraminidase following exposure to acidic pH are supposed to be linked together in avian influenza virus strains implicating neuraminidases for their ability to prevent the aggregation of virions.

Hydrogen-Ion Concentration↗
PubMed1981

[Ultrastructural study of the effects of neuraminidase on the palatine process of the rat].

In a previous work, we demonstrated that palatine processes treated with 10 micrograms/ml neuraminidase for 30 minutes at 37 degrees C show a delayed fusion in vitro. In order to investigate the effects of neuraminidase, the treated palatine processes were observed with the aid of transmission and scanning electron microscopy. The effect of neuraminidase is exclusively detectable on superficial flat cells of the palatine processes, especially the cells of the medial edge of the process. The epithelial basal cells remain unchanged. Observed with the S.E.M., the superficial epithelial cells show bubbles, become spherical and detached. To explain these observations, we namely propose the following hypothesis: the action of neuraminidase prevents the fusion of the palatine processes because it denudes basal cells bearing a too immature cell coat for ensuring sufficient adherence between the palatine processes.

Animals↗
PubMed1981

Erythropoiesis in vitro: enhancement by neuraminidase.

Neuraminidase treatment of human fetal liver or adult marrow cells prior to culture results in an increased number of erythroid colonies and bursts. No increase occurs in the number of nonerythroid colonies. The number of bursts having more than eight subunits is increased preferentially. Individual burst subunits are also enlarged. Neuraminidase-treated cells yield erythroid bursts when cultured in concentrations of erythropoietin insufficient to produce bursts from untreated cells. It is proposed that (1) neuraminidase treatment of adult and fetal cell mixtures specifically stimulates differentiation of erythroid precursors, (2) the preferential stimulation of erythroid bursts having many subunits suggests a preferential susceptibility of more primitive BFU-Es, and (3) neuraminidase treatment enhances the response of erythroid precursors to erythropoietin.

Bone Marrow↗
PubMed1978

[Immunelectrophoretical evidence on inactivation of neuraminidase by limulus polyphemus-amebocyte-lysate (author's transl)].

Neuraminidase in concentrations up to 0.5 nu/0.1 ml (0.05 nu/0.1 ml) added to Limulus amebocyte lysate (LAL) in equal volumes (each 0.1 ml) releases a gelation reaction. Human AB-serum - subjected to immunelectrophoresis - is used as an indicator system to show that neuraminidase is bond to the LAL (incorporated in the gel). If there is a free amount of neuraminidase immunelectrophoresis of the serum glycoproteins indicates the typical changes previously described by Müller (6, 7). LAL does not cause any immunelectrophoretically detectable changes on serum glycoproteins by itself in the temperature range from +4 degrees C to 37 degrees C. It must be assumed that neuraminidase in a certain amount is releasing the coagulation system.

Enzyme Inhibitors↗
PubMed1976

Clinical evaluation of neuraminidase monospecific (HEqN2) recombinant influenza vaccine in children.

Phased clinical trials were undertaken to evaluate the efficacy of neuraminidase specific recombinant (HEqN2) inactivated influenza vaccine in a population of school children. Groups of subjects were immunized under code, with influenza A2 Port Chalmer (H3N2), Port Chalmer neuraminidase recombinant (HEqN2), and placebo vaccines (vaccine diluent) before the onset of A2 strain influenza epidemic in this population. Preliminary results have provided the following information. Immunization with commercial Port Chalmer (H3N2) or neuraminidase recombinant influenza A2 (HEqN2) vaccines, in a childhood population was safe and without any major adverse effects. Vaccination with H3N2 vaccine regularly induced seronconversion for specific hemagglutination-inhibiting (HAI) antibodies in over 60% of vaccinated subjects. The mean titers of antineuraminidase antibody (ANAB) in H3N2 recipients who were seropositive prior to immunization increased five-fold while the ANAB titers of individuals who were seronegative prior to immunization did not rise significantly after immunization. On the other hand, immunization with HEqN2 vaccine resulted in little or no HAI response against H3, while specific ANAB response was observed in over 70% of such vaccines. The ANAB titers increased approximately 10 fold in the vaccines who were seropositive prior to immunization, and the titers in subjects seronegative prior to immunization were 5-6 fold higher than the post immunization titers observed in seronegative individuals in the H3N2 vaccinated group. Preliminary data on protection against natural reinfection suggested that, although the incidence of serological reinfection was similar in all vaccine groups, the expression of clinical disease was somewhat milder in HEqN2 vaccinees and in individuals with high levels of ANAB. These studies provide tentative support to the potential use of neuraminidase specific vaccine for mass immunoprophylaxis against influenza A2 virus.

Adolescent↗