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N Kessler

Publications and source records attributed to N Kessler.

31 records · Page 2Linked to original sources
PubMed1990

Correlation between the reactivity patterns of monoclonal antibodies to distinct antigenic sites on HN glycoprotein and their protective abilities in Sendai (6/94) virus infection.

The relative importance of the host immune response to various antigenic and functional sites on the HN glycoprotein of Sendai (6/94) virus for protection in vivo, was evaluated in mice passively immunized with monoclonal antibodies to HN and then intranasally challenged with infectious virus. Five neutralizing monoclonal antibodies reacting with distinct antigenic sites and exhibiting different reactivity patterns were selected. All of them were able to prevent entirely the growth of virus in the lungs of experimental animals injected with appropriate dilutions of monoclonal antibody. The calculation of correlation coefficients between the reduction of virus in the lungs of immunized mice and the amount of antibody, expressed in terms of hemagglutination inhibition, hemolysis inhibition or neutralizing units, showed a high degree of correlation (r = 0.89) with neutralization and a lack of correlation (r = 0.44) with hemagglutination inhibition. In parallel a minimum threshold value for protection equivalent to 2 x 10(3) neutralizing units per mouse was determined independently of the mechanism(s) by which monoclonal antibodies mediated the neutralization of the infectivity. On the HN glycoprotein of Sendai (6/94) virus we could not individualize a critical site for successful immune recognition by antibodies although the characteristics of an "ideal protective monoclonal antibody" have also been defined.

Animals↗
PubMed1986

Catalytic properties of the A/H3N2 influenza neuraminidases: influence of antigenic variations.

Antigenic variation of the neuraminidase of A/H3N2 influenza viruses may be associated with modifications of the catalytic activity of this enzyme. We observed this phenomenon when studying two prototype strains: A/Hong Kong/1/68 (X31K) and A/Bangkok/2/79. For the neuraminidases of these strains, we determined their substrate specificity, initial velocity, optimum pH, optimum temperature, heat inactivation and Michaelis constants and their inactivation by chemical group-specific reagents. In order to examine the relationship between antigenic variation and enzyme activity of the influenza neuraminidases, three X31K monoclonal variants were selected using anti-neuraminidase monoclonal antibodies. Two of these (X31/NC92 and X31/NC56) were modified at a single neuraminidase epitope, and the third one (X31/NC92/NC56) at two epitopes. The neuraminidase activity of the monoclonal variants was analysed and compared to that of the prototype strains. Compared to A/Hong Kong/1/68, the A/Bangkok/2/79 strain neuraminidase was more susceptible to inactivation by physical (pH, temperature) and chemical agents [urea, dithiothreitol, 1-ethyl-3-(3-dimethylaminopropyl carbodiimide), iodoacetamide, acetic anhydride, 2,3-butanedione] and showed a twofold lower substrate affinity for N-acetylneuraminlactose. The neuraminidase activity of the monoclonal variants of X31K became more susceptible to inactivation by both physical and chemical agents than the original strain and exhibited various substrate affinities. Therefore, we conclude that the enzymic properties of the structurally conserved active sites of the neuraminidase molecule may be influenced by antigenic modifications that affect the variable areas of the neuraminidase and that the degree of this enzymic variation is related to the nature and number of the modified epitope(s). A local conformational change in the neuraminidase molecule reflected as antigenic variation could be involved in modification of enzyme activity.

Antigens, Viral↗
PubMed1984

Contribution of monoclonal antibodies to the study of parainfluenza virus antigens.

Splenic lymphocytes from BALB/c mice immunized with Parainfluenza 1 virus (PIV-1), HA2 strain, were fused to the non secreting 653 and secreting P3 X 63Ag8 myeloma cell lines. Fusion products were screened for antibody synthesis using an enzyme-linked immunosorbent assay (ELISA) with purified PIV-1. Antibodies were characterized by their biologic specificity and immune fluorescence staining--6 monoclones (2HI and 4 non HI) were used to further analysis by cross reactivity panels using different PIV strains. None of the anti PIV1 monoclones showed any cross reactivity with PIV2 and PIV3 whereas with HI and non HI monoclones antigenic relationships were observed between viruses belonging to serotype 1. Monoclonal antibodies were also applied to the study of host cell related changes in PIV1 proteins.

Animals↗
PubMed1981

Biological properties and carbohydrate composition of human parainfluenza virus type 1 in two host systems.

Human parainfluenza virus type 1 (HA2 virus) grown either in embryonated hens' eggs or in M. rhesus monkey kidney cells showed differences in size, biological properties and carbohydrate composition. Egg-grown virus showed a larger size (233 nm versus 167 nm), a higher neuraminidase activity (specific activity and initial and maximum velocity) and a higher haemolytic activity than monkey kidney cell-grown virus. The haemagglutinin titre was identical for the HA2 strain grown in both host systems when tested with human O Rh+, guinea-pig and hen red blood cells, but reduced by more than 100-fold when tested with grivet monkey red blood cells. In addition, the carbohydrate content (mainly neutral sugars) was higher in egg-grown virus (9.2%) than in virus grown in MK cells (5.7%), and the amino to neutral sugar ratio was lower (1.2 versus 2.1). The sugars were identified as fucose, mannose, galactose, glucose, glucosamine and galactosamine. The prominent neutral monosaccharide was glucose in egg-grown virus and fucose in MK cell-grown virus. HA2 virus infection of MK cells increased fucose and glucose, and decreased mannose and galactose levels.

Animals↗
PubMed1980

[Rapid serodiagnosis of influenza by a modified radial haemolysis test: immune response (author's transl)].

A modification of the single radial haemolysis test by treatment with Cl3Cr of the virus coated red blood cells is proposed for a rapid, more sensitive and reproducible serodiagnosis of Influenza infections. The reagents "red blood cells-virus-Cl3Cr" is stable at 4 degrees C for at least 1 month: the modified test gives results within 3 hours, in measuring the H-anti-H specific reactions. The anti-influenza A immune response was studied in patients of different age, bled at different time after exposure. The IgM do not diffuse in the agarose and do not haemolyse. A clear haemolytic area is produced by IgG, partially haemolysed areas occur when there is a competition between specific IgM and IgG and in the case of reactions involving cross-reacting antigenic determinants.

Adolescent↗
PubMed1979

Study of a new strain of paramyxoviruses isolated from wild ducks: antigenic and biological properties.

Among the different strains of avian paramyxoviruses isolated from migrating feral ducks, two were identified as Newcastle disease viruses (NDV) and the five others would correspond to a new serotype for which we suggest the name of Duck/Mississippi/75 virus. The characteristics of this new serotype are as follows: (1) Duck/Mississippi/75 virus is able to grow as well in allantoic as in amniotic cavities of embryonated hen's eggs; (2) the haemagglutinin and haemolytic activities can be detected with hen red blood cells; (3) the neuraminidase hydrolyses the alpha 2 leads to 3 bonds of the fetuin substrate and its pH activity could be species specific. Antigenically, this serotype is different from all human and animal paramyxoviruses, in spite of an antigenic relationship with NDV.

Animals↗
PubMed1979

Study of a new strain of paramyxoviruses isolated from wild ducks: structural polypeptides.

By polyacrylamide gel electrophoresis, Duck/Mississippi/75 virus was shown to contain five different types of polypeptides of mol. wt. ranging from 76 X 1O(3) to 43 X 10(3), two of which were glycosylated (mol. wt. 76 X 10(3) and 57 X 10(3). A comparison of this data with similar results obtained using Yucaipa and Newcastle disease virus (NDV) revealed a similarity with NDV, concerning the number, position and mol. wt. of the polypeptides. Haemagglutinating and neuraminidase properties are associated with surface glycoproteins which represent at least 40% of the virus protein. After KCl and Triton X-100 treatment and centrifugation on linear sucrose density gradients (10 to 25%, w/w) it was possible to isolate glycoprotein VP1 of mol. wt 76 X 10(3) with which haemagglutinating and neuraminidase activities were associated.

Animals↗
PubMed1979

Antigenic and structural relationships between avian paramyxoviruses isolated from ducks in Hong Kong and Mississippi, U.S.A.

Representative isolates of the paramyxoviruses duck/Hong Kong/75 and duck/Mississippi/75 were shown to be serologically closely related by haemagglutination and neuraminidase inhibition tests. The structural polypeptides of these viruses were also shown to be similar. For each of the isolates tested, polyacrylamide gel electrophoresis in the presence of SDS revealed a similar polypeptide pattern consisting, under reducing conditions, of seven polypeptides with apparent mol. wt. ranging from 46000 to 190000. Each virus had two glycosylated polypeptides with apparent mol. wt. of 56000 and 71000 to 72000 under reducing conditions and 62000 to 63000 and 135000 to 142000 under non-reducing conditions.

Animals↗
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↗
PubMed1977

[The effect of portacaval anastomosis and liver arterialization on the oxygen supply of the normal and the cirrhotic liver].

The application of the Platinum-Multiwire Surface electrode for local oxygen determination permits the determination of microcirculatory changes in the normal and cirrhotic liver. The normal liver is capable of compensating for portal blood deprivation whereas in the cirrhotic liver shunting of portal blood leads to a striking hypoxia of the liver tissue. Lack of oxygen can be prevented by means of arterialization, but despite oxygen adaptation at the time of operation uncontrollable hyperoxygenation can occur as well.

Animals↗
PubMed1975

Morphology, biochemical analysis and neuraminidase activity of rubella virus.

A simple and reproducible method for the production of purified rubella virus is described. Purified virus was subjected to morphological and chemical analysis. The virus particles were rather pleomorphic (60 nm diameter), sometimes with one or more peripheral protrusions. The viral surface, revealed by negative staining, was composed of spikes 6 nm long, featuring enlarged ends. In SDS-urea-polyacrylamide gel electrophoresis, 4 major and 4 minor polypeptide bands were revealed. Total lipids and phospholipids were analysed on the same preparation. The viral particles were composed of RNA: 0.030 mg, and lipids: 0.245 mg, of which 0.169 mg were phospholipids for each mg of viral protein. Biologically, the purified virus preparation showed high infectivity, a high hemagglutination titre and a weak neuraminidase activity under defined conditions.

Cell Line↗
PubMed1975

Contribution to the study of the parainfluenza antigens.

From epidemiological data it appeared that an epidemic of parainfluenza type 1 occurred in Lyons in October-November 1967. Thereafter a few sporadic cases were detected. Then in 1970 strains were isolated which showed a change in the hemagglutinin antigen. The persistence of antibodies in the population is shorter than that of the other parainfluenza viruses (i. e. parainfluenza 3); it is not known if reinfections with parainfluenza 1 occur since there are cross-reactions by CF test between parainfluenza 1 and parainfluenza 3 which are known to cause reinfections. The study of antigens of parainfluenza strains was made by HI, Nt, CF and immunodiffusion tests with various antisera prepared in various animal species. This study showed antigenic differences and similarities between parainfluenza 1 and parainfluenza 3.

Animals↗