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Biomedical subjects

B Morein

Publications and source records attributed to B Morein.

At least 145 records · Page 8Linked to original sources
PubMed1979

Integration of a virus membrane protein into the lipid bilayer of target cells as a prerequisite for immune cytolysis. Specific cytolysis after virosome-target cell fusion.

Structural requirements for membrane antigens on target cells to mediate immune cytolysis were studied in a model system with purified membrane proteins from Semliki Forest virus (SFV). These SFV spike proteins were isolated in the form of detergent- and lipid-free protein micelles (29S complexes) or, after reconstitution into lipid vesicles, in the form of virosomes. Both the 29S complexes and the virosomes were found to bind well to murine tumor cells (P815 or Eb). When these cells, however, were used as target cells in complement-dependent lysis or in antibody-dependent cell- mediated cytotoxicity assays in the presence of anti-SFV serum, they were not lysed, although they effectively bound the antibody and consumed complement. The same tumor cells infected with SFV served as positive controls in both assays. Different results were obtained when inactivated Sendai virus was added as a fusion reagent to the cells coated with either virosomes or 29S complexes. Under these conditions the virosome-coated cells became susceptible to SFV- specific lysis, whereas the 29S complex-coated cells remained resistant. Evidence that the susceptibility to lysis ofvirosome-coated cells was dependent on active fusion and, therefore, integration of the viral antigens into the lipid bilayer of the target cells was derived from control experiments with enzyme-treated Sendai virus preparations. The 29S complexes and the virosomes partially and selectively blocked the target cell lysis by anti-H-2 sera but not by anti-non-H-2 sera confirming our previous finding that major histocompatibility antigens serve as receptors for SFV. The general significance of these findings for mechanisms of immune cytolysis is dicussed.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1979

Helix pomatia a hemagglutinin, a surface marker for bovine T-lymphocytes.

Bovine peripheral blood lymphocytes (PBL) were isolated from blood collected from 6 cattle. After treatment with neuraminidase, 40 or 60% of the cells were shown to combine with Helix Pomatia A hemagglutinin (HP) depending whether a direct or indirect fluorescence technique was used. About 20% of the cells were Ig-bearing. With double staining fluorescence technique, it was shown that cells attaching to HP were not Ig-bearing and the reverse. With the aid of HP, covalently bound to Sepharose, Ig-bearing cells could be separated from cell populations attaching to HP. The fraction of cells forming rosettes with sheep erythrocytes was proportional to that of HP attaching cells both before and after fractionation on the HP column. It is therefore concluded that HP is a marker for bovine T-cells, and that this lectin may be used to separate B-cells from T-cells.

Animals↗
PubMed1978

Human (HLA-A and HLA-B) and murine (H-2K and H-2D) histocompatibility antigens are cell surface receptors for Semliki Forest virus.

The proteins coded for by the HLA-A and HLA-B loci in man and the H-2K and H-2D loci in mice were identified as cell surface receptors for Semliki Forest virus. This conclusion is based on the following observations: (i) Water-soluble octamers of viral coat proteins inhibit the complement-dependent cytotoxicity of antibodies directed against H-2K and H-2D antigens in mouse cells. (ii) Isolated detergent-soluble HLA-A and HLA-B antigens reconstituted in lipid vesicles inhibit the binding of viral proteins to human cells (as do the water-soluble antigens to a lesser extent). (iii) Reconstituted HLA-A and HLA-B vesicles interact in solution with Semliki Forest virus (or with vesicles containing viral spike proteins), as demonstrated by coprecipitation with antisera. (iv) Complexes between viral spoke proteins and HLA-A and HLA-B antigens or H-2K and H-2D antigens can be isolated from the cell surface by utilizing affinity chromatography or immunoprecipitation.

Animals↗
PubMed1978

Humoral immune response to infection with Encephalitozoon cuniculi in rabbits.

Parenteral administration of Encephalitozoon cuniculi induced an antibody response within 7--11 days. Peroral administration was less effective since only 2 of 6 animals showed seroconversion; they became seropositive within 14--21 days. Sera from animals which became seropositive had high antibody titres during the whole test period. Immune sera from 3 animals were fractionated by gel filtration. With the india-ink immunoreaction test, antibodies to E. cuniculi were found only in the 7S fractions, while the indirect fluorescent-antibody test detected them in fractions 19S and 7S. The 7S fractions were identified as IgG and the 19S fractions as IgM. A program for eradication of encephalitozoonosis, based on these results, is discussed.

Animals↗
PubMed1977

Components of parainfluenza-3 virus, SLP-strain, reacting in assays of cell-mediated immunity in cattle.

Parainfluenza-3 virus was isolated by affinity chromatography, including a purification step with immobilized lectin Vicia erwilia. The peplomers of disintegrated virus were similarily isolated using another carbohydrate-specific lectin Vicia crotalaria. The whole virion and the peplomers were both active as antigens in the leucocyte migration inhibition, lymphocyte stimulation and skin hypersensitivity tests. The remaining virus material, freed of detergents used for virus disintegration and containing nucleocapsids, did not act as antigen in these tests of cell-mediated immunity.

Adsorption↗
PubMed1977

In vitro stimulation of bovine circulating lymphocytes by parainfluenza type 3 virus.

Bovine circulating lymphocytes from animals sero-positive to parainfluenza-3 virus (PIV-3) could be stimulated by PIV-3 antigen in a microculture system. A semiautomatic multiple sample harvester was used to collect the lymphocytes from the microplates. Ultraviolet-killed PIV-3 induced better stimulation values than formalin or heat-treated virus. The highest stimulation values were obtained after a stimulation time of three to five days.

Animals↗
PubMed1977

Age-dependent presence of fetuin in bovine nasal secretion.

At least two age-dependent proteins were detected in nasal secretion (NS) of young calves by crossed immunoelectrophoresis. One of them was identified as fetuin. The other one was not identified. The concentration of fetuin in NS was found to increase in cases where a sample of NS had been obtained at birth and a second sample taken within 11 days. Thereafter a decrease was always found towards day 15 or 30.

Age Factors↗
PubMed1975

Quantification of the inhibitory effect of eriochrome black and sodium nitrite on non-specific immunofluorescent staining.

To evaluate non-specific staining (NSS) of animal tissues by FITC-labelled immunoglobulins a model system was developed. HeLa cells were treated with labelled antisalmonella globulins and the fluorescence intensity of the cells was determined quantitatively by means of a fibre optic probe system. This system was used to determine the optimal treatment conditions (adequate concentrations, duration of treatment) using the two NSS-reducing agents eriochrome black and sodium nitrite. Approximately the same inhibitory effects (40-50 per cent using nitrite; about 85 per cent using eriochrome black) were obtained by conjugates of different F/P ratio values. The fibre optic probe system was also used to determine the effects of the above-mentioned agents on the NSS of liver sections. In this system, the NSS was strongly reduced by eriochrome black whereas nitrite treatment did not induce any inhibitory effect. The applicability of nitrite and eriochrome black as NSS-reducing agents was further demonstrated by the fact that they had no influence on the specific fluorescence intensity of salmonella bacteria. The effect of eriochrome black was also studied in clinical specimens infected with salmonella or tularemia bacteria.

Animals↗
PubMed1975

Studies on parainfluenza-3 virus neuraminidase.

Various parainfluenza-3 virus (PIV-3) strains differ in neuraminidase (NA) activity, some being neuraminidase strong (NAS) and some neuraminidase weak (NAW). No difference in the ability of these strains to elicit antibody activity to hemagglutinin (HA) or NA of PIV-3 was observed. Samples of formalin-treated PIV-3 released more N-acteylneuraminic acid (NANA) than samples of Piv-3 not treated with formalin when these samples were incubated with the substrate sialolactose for 16 h at 37 degrees C. The initial activity of PIV-3 NA, and the Km-value, were similar for a NAS strain whether it was treated with formalin or not. The results suggest that formalin stabilized the NA structure of PIV-3. A NAS strain of PIV-3 dialyzed against distilled water showed an increased initial neuraminidase activity as compared to virus dialyzed against isotonic NaCL or to non-dialyzed virus. The increased enzyme activity indicates an increased affinity of NA tothe substrate sialolactose as an increased Km-value was also obtained. It is suggested that PIV-3 neuraminidase facilitates the penetration of the virion through the mucociliary barrier of the respiratory tract by releasing the virus from inhibitors in the gel phase. It has been found that antibody in the gel phase of nasal secretion inhibits the NA activity of PIV-3 Following exposure of a gel phase of bovine tracheal secretion to a NAS strain of PIV-3 an increased initial viscosityof this phase was observed. The gel phase of bovine nasal secretion showed a structural change in scanning electronmicroscopy following exposure to a NAS strain. Stimultaneously an increased amount of free N-acetylneuraminic acid was found in the gel.

Animals↗
PubMed1974

Effect of parainfluenza-3 virus neuraminidase on the structure of the gel phase of bovine nasal secretion.

The gel phase of bovine nasal secretion was separated from the liquid phase and exposed to parainfluenza-3 virus or Vibrio cholerae neuraminidase under optimal in vitro conditions. N-Acetylneuraminic acid was released from the gel by either neuraminidase. The release of N-acetylneuraminic acid was accompanied by a decrease in the net negative charge of the gel, as evidenced by free zone electrophoresis. Scanning electron microscopy showed that after exposure to neuraminidases the regular network structure of the untreated gel attained a coarse, irregular structure. Samples of gel incubated with 0.15 M sodium chloride under similar conditions did not show changes in the net charge or morphology.

Animals↗