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Biomedical subjects

B Morein

Publications and source records attributed to B Morein.

At least 127 records · Page 7Linked to original sources
PubMed1987

Antigenic presentation of small molecules and peptides conjugated to a preformed iscom as carrier.

The aim of the present study was to elaborate a carrier system for haptens and synthetic peptides, making them immunogenic without addition of Freund's adjuvants. As carriers, preformed iscoms and micelles as well as BSA have been compared. The iscoms and micelles were prepared with envelope proteins of an influenza virus. As a model hapten, the small molecules of biotin were coupled to iscoms to determine the optimum epitope density for induction of an enhanced antibody response to the hapten. The most efficient carrier tested was the preformed iscom at an epitope density of ten biotin molecules per viral protein in the iscom. This carrier system exceeded the efficacy of both the preformed micelles and BSA, the latter with or without addition of Freund's adjuvant. A favourable epitope density could not be achieved when each of two different synthetic peptides was conjugated to iscoms. Epitope densities higher than one to three peptide molecules per protein lead to polymerization of either the peptide or the carrier. The coupling agent was glutardialdehyde.

Adjuvants, Immunologic↗
PubMed1987

A specific assay measuring binding of 125I-Gp 120 from HIV to T4+/CD4+ cells.

The HIV (HTLV-III) envelope glycoprotein, Gp120, was isolated from virus-infected tissue culture cells using affinity chromatography. A radioimmunoassay was developed to determine the degree of iodinated Gp120 to target CD4+ (T4+) cells. 125I-Gp120 could be shown to selectively bind to CD4+ cells only. The Gp120 remained bound to these cells after repeated washes. Monoclonal anti-CD4 antibodies block the binding of Gp120 to CD4+ cells. Monoclonal antibodies to other cell surface components do not interfere with 125I-Gp120 binding. All IgG antibodies from HIV seropositive donors tested block 125I-Gp120 binding, though with variable titers. We believe that this assay provides further proof for the use of CD4 (T4) as a component of the receptor for HIV. It represents a safe, objective and sensitive method for the analysis of Gp120-CD4 interactions, as well as the potential of antibodies to interfere with this binding.

Antibodies, Monoclonal↗
PubMed1987

Monocyte and iscom enhancement of cell-mediated response to cytomegalovirus.

Cell-mediated and humoral responses to cytomegalovirus were studied in a monkey model. Repeated low doses of virus antigen gave poor reactivities in both respects. High antigen doses gave a good humoral IgG response. When autologous monocytes were incubated with the CMV antigen as the immunizing injection, the specific cellular response to CMV antigen increased. The monocytes themselves did not contribute to the in vitro specific proliferation response. When iscoms were the carrier particles for CMV antigens, cellular response was even more strongly enhanced. In immunization schedules where specific cellular responses are important, we suggest that autologous monocytes or iscoms may be employed as antigen carriers.

Animals↗
PubMed1987

Potentiation of the immune response by immunization with antigens in defined multimeric physical forms.

Conventional vaccines consisting of whole microorganisms have in many cases proven ineffective. This has led to the development of subunit vaccines which contain defined protective antigens. However, subunit vaccines are frequently poorly immunogenic, requiring the addition of adjuvants and/or their formation into forms such as micelles or virosomes. Ideally a vaccine should be limited to the desired antigens, incorporated in a multimeric physically defined form into which the adjuvant is built. This is possible through use of the ISCOM (immuno-stimulating complex), a matrix of the glycoside Quil A, onto which antigens are attached by hydrophobic interaction. Experiments involving ISCOMs prepared using membrane proteins from several viruses are described. The ISCOM system can be used to enhance immune response to antigens prepared from microorganisms and cells as well as peptides and other small molecules.

Adjuvants, Immunologic↗
PubMed1987

Preparation and properties of immune-stimulating complexes containing hepatitis B virus surface antigen.

Immune-stimulating complexes (iscoms) have been prepared containing the major S gene products (HBsAg) of the hepatitis B virus genome. Immunization of BALB/c mice with a single dose of hepatitis B iscoms in saline resulted in a high titre antibody response to HBsAg. In contrast, the original HBsAg preparation required an adjuvant to produce equivalent amounts of antibody. Analysis of sera from mice immunized with hepatitis B iscoms revealed antibodies directed against the major a determinants of HBsAg. High secondary antibody responses were observed in immunized animals previously inoculated with a sub-immunogenic dose of HBsAg indicating that hepatitis B iscoms may represent a suitable immunogen for use in individuals in whom a course of immunization with currently licensed hepatitis B vaccines has failed to produce a significant anti-HBs response.

Animals↗
PubMed1987

Protection against lethal measles virus infection in mice by immune-stimulating complexes containing the hemagglutinin or fusion protein.

The importance of each of the two surface glycoproteins of measles virus in active and passive immunization was examined in mice. Infected-cell lysates were depleted of either the hemagglutinin (H) or fusion (F) glycoprotein by using multiple cycles of immunoaffinity chromatography. The products were used to prepare immune-stimulating complexes (iscoms) containing either F or H glycoprotein. Such complexes are highly immunogenic, possibly as a result of effective presentation of viral proteins to the immune system [B. Morein, B. Sundquist, S. Höglund, K. Dalsgaard, and A. Osterhaus, Nature (London) 308:457-460, 1984]. Groups of 3-week-old BALB/c mice were inoculated with the iscom preparations. All animals developed hemolysis-inhibiting antibodies, whereas only sera of animals immunized with the iscoms containing the H glycoprotein had hemagglutination-inhibiting antibodies. Sera from animals immunized with the H or F preparation only precipitated the homologous glycoprotein in radioimmune precipitation assays. The immunized animals were challenged with a lethal dose of the hamster neurotropic variant of measles virus. Of the 7-week-old animals in the nonimmunized control group, 50% died within 10 days after challenge. No animals in the immunized groups showed symptoms of disease throughout the observation period of 3 months. Passive administration of anti-H monoclonal antibodies gave full protection against the 100% lethal acute infection with the hamster neurotropic variant of measles virus in newborn mice, whereas anti-F monoclonal antibodies failed to protect the animals. This study emphasizes that both H and F glycoproteins need to be considered in the development of measles virus subunit vaccines.

Animals↗
PubMed1985

Subunit vaccines against enveloped viruses: virosomes, micelles and other protein complexes.

The envelope proteins (the peplomers) of enveloped viruses are the components that are important for induction of protective immunity. This article reviews methods and problems of making subunit vaccines of peplomers. In the first section, the solubilization of enveloped viruses with detergent is discussed. The preparation of envelope proteins into defined different physical forms is described, i.e. monomeric and micelle forms and the reconstitution of the protein into lipid vesicles (virosomes). Finally, the preparation of a new type of complex is described (named iscom), which is highly immunogenic. In the following sections the efficacy of the different physical forms are reviewed and it is concluded that monomeric forms must be avoided since they are poorly immunogenic and they may even have a suppressive effect on the immune response. The multimeric micelles, virosomes and iscoms are all immunogenic. The iscom is an interesting new concept that can be used to produce efficient subunit vaccines.

Adjuvants, Immunologic↗
PubMed1985

Induction of protective immune response in cats by vaccination with feline leukemia virus iscom.

An effective candidate subunit vaccine consisting of the gp 70/85 of feline leukemia virus (FeLV) was prepared by using the immunostimulating complex (iscom) method for the presentation of membrane proteins of enveloped viruses. Two 32-wk-old specific pathogen-free (SPF) cats were immunized with a FeLV iscom vaccine prepared from the supernatant fluid of the FL74 tumor cell line without adjuvant. Both cats developed FeLV serum antibodies, as measured in an enzyme-linked immunosorbent assay (ELISA) and in a virus neutralization test. A proportion of the antibodies were directed to an epitope located on gp70/85, which was shown in competition ELISA with a peroxidase-labeled virus-neutralizing monoclonal antibody to be shared by all three subtypes of FeLV. The protective effect of FeLV iscom was studied by vaccinating six 8-wk-old SPF cats with iscom prepared from cell culture supernatant of another tumor cell line F422, followed by oronasal challenge with 10(6) ffu FeLV-A (strain Glasgow-1). Six unvaccinated cats were also challenged with the same dose of FeLV. The vaccinated cats developed FeLV serum antibodies, some of which were directed to the shared epitope on gp70/85. At 10 wk after challenge, none was viremic, whereas three of the control cats had developed FeLV viremia. The potential of FeLV iscom as a vaccine against FeLV-associated disease in cats, and of iscom vaccines for protection against mammalian retrovirus infections, is discussed.

Adjuvants, Immunologic↗
PubMed1985

Suppressor activity of bovine Fc gamma positive cells during a persistent infection with Mycobacterium avium.

The cell mediated immune response (CMI) was measured in calves after experimental infection with Mycobacterium avium. Using the tuberculin skin test a CMI response could be measured from four to 14 weeks after infection, and with a lymphocyte stimulation (LS) test from six to 40 weeks. One year after infection no CMI response was detected by either of the tests, in spite of the fact that in such calves M avium bacteria could be found in the intestinal lymph nodes at autopsy. After removal of mononuclear cells bearing receptors for the Fc part of IgG, the peripheral blood lymphocytes obtained from a calf infected one year earlier responded to M avium pure protein derivative in the LS test in contrast to lymphocytes obtained from uninfected calves.

Animals↗
PubMed1983

Assay of detergents by rocket electrophoresis in agarose gels containing red blood cells: "rocket hemolysis".

A method is described for quantitation of charged detergents using their hemolytic property in an electrophoresis assay in agarose gels containing red blood cells. After electrophoresis the zone of hemolysis is directly proportional to the concentration of detergent in the sample. Using this technique we have determined the smallest detectable concentration for the negatively charged detergents, sodium dodecyl sulfate (SDS) and Quil A to about 10 micrograms/ml and 25 micrograms/ml, respectively and the positively charged cetyltrimethylammonium bromide (CTAB) to about 10 micrograms/ml.

Animals↗
PubMed1983

Evaluation of labelling methods for bovine T and B lymphocytes.

Two lectins, one from Helix pomatia (HP) and one from Peanut (PN), were evaluated as bovine T cell markers. HP attaches to about 40% of the bovine peripheral blood lymphocytes (PBL). With an indirect technique about 60% of PBL are HP positive, while PN attaches to a slightly higher proportion of the PBL. In double labelling experiments, HP was shown to bind only to Ig negative cells while 2% of the PBL were double labelled with PN and anti-Ig. The influence of different pretreatments of the PBL or the antibodies for labelling of the membrane bound Ig was studied. Preincubation for detaching cytophilic antibodies was important to avoid false Ig positive cells.

Animals↗
PubMed1983

Protein subunit vaccines of parainfluenza type 3 virus: immunogenic effect in lambs and mice.

Protein subunit vaccines were prepared from a mixture of the haemagglutinin (HN) and fusion (F) glycoproteins of parainfluenza type 3 virus (PI-3). The glycoproteins were isolated in three different forms and characterized by their sedimentation coefficients: 30S protein micelles (a complex of several HN and F glycoproteins devoid of detergent and lipid), 18S protein-TX complexes (a complex of several glycoproteins containing the detergent Triton X-100), and 4S protein-TX complexes (probably monomers of the glycoproteins complexed to Triton X-100). These preparations were tested as vaccines in mice and lambs. The immune response in the mice was assayed both in the serum and in extracts from the lungs using an ELISA technique. Both of the multimeric complexes were highly immunogenic. The 30S protein micelles induced a high antibody response after two injections with either 10 or 1 microgram protein. The serum IgG titres reached levels of about 90 micrograms/ml and 40 micrograms/ml respectively. Similar titres were reached with the 18S protein-TX complexes. After two injections of either the 30S or the 18S complexes IgA antibody responses were detected in the lung extracts. The 4S protein-TX complexes were poor immunogens and induced low antibody responses in mice. The lambs were vaccinated with the 30S protein micelles, and the immune response was evaluated serologically and in challenge experiments. The 30S protein micelles in an oil adjuvant induced detectable serum antibody titres as well as protective immunity against the pneumonia caused by the PI-3 virus.

Animals↗
PubMed1980

Characterization and response to mitogens of mammary lymphocytes from the bovine dry-period secretion.

From bovine mammary secretion during the dry period, the total number of cells was between 1.2 and 5.9 X 10(6)/ml. A mean of 35% of these cells were classified as lymphocytes and approximately 85% of them could be isolated by the Ficoll-isopac method. Centrifugation separated 6% of the cells into the fat; 5% of them were lymphocytes. About 47% of the lymphocytes bound Helix pomatia agglutinin, a T-cells marker, while the proportion of Ig-bearing cells was approximately 28%. The mammary lymphocytes were stimulated by the lectins phytohaemagglutinin, pokeweed mitogen, concanavalin A and by lipopolysaccharide from Salmonella typhimurium. The stimulation indices of mammary lymphocytes were generally lower than those for peripheral blood lymphocytes from the same animals. The background values, i.e. counts/min of lymphocytes incubated without mitogen, were often higher for lymphocytes isolated from mammary secretion than from blood.

Animals↗