Search PubMed⌕ Search

Biomedical subjects

B Morein

Publications and source records attributed to B Morein.

At least 91 records · Page 5Linked to original sources
PubMed1990

Effect of iscoms and their adjuvant moiety (matrix) on the initial proliferation and IL-2 responses: comparison of spleen cells from mice inoculated with iscoms and/or matrix.

In the iscom, antigen is attached by hydrophobic interactions to a matrix which is built up by the adjuvant Quil A and lipids. Thus, the iscom presents antigen in multiple copies on a small particle with a built-in adjuvant. By studying the specific antibody response, in vitro proliferation and IL-2 secretion by splenocytes from mice following different in vivo treatments with iscoms and/or matrix, we attempted to distinguish between nonspecific stimulatory effects, caused by the matrix or iscoms, and specific responses to the antigens incorporated into iscoms. The results strongly suggest that matrix and also iscoms exert a nonspecific adjuvant activity by a transient high spontaneous proliferation of cells collected within 2 weeks after administration of iscoms or matrix. This high rate of proliferation was preceded by suppressed proliferation, 3 days after injection with matrix or iscom. The adjuvant component included in iscoms, i.e., the matrix, does not excert a mitogenic stimulation in vitro or influence the levels of specific antibodies in serum. Specific responses to the antigens included in iscoms were recorded both as increasing levels of serum antibodies and as iscom-induced proliferation of immune spleen cells in vitro. The recruitment of IL-2 was only related to the specific stimulation induced by the antigens in iscom.

Adjuvants, Immunologic↗
PubMed1990

The iscom: an immunostimulating system.

To make purified antigens highly immunogenic, they have to be presented in several copies in the form of a microscopic or submicroscopic particle. This is the case, regardless of whether the antigens are obtained by isolation from conventional microorganisms, or from gene-manipulated cells, or synthesized. In the iscom, the antigens are attached as multimers to a 40-nm cage-like particle with a built-in adjuvant. The antigens in iscoms are rapidly transported from the injection site to the draining lymphatic organ. Iscom-borne antigens induced a 10-fold higher antibody response than the same amount of antigen in micelle form. One intranasal immunization with influenza virus iscoms induced protection to intranasal challenge infection in mice. Besides a strong antibody response in all Ig classes and isotypes, cytotoxic T cells were induced. With iscoms containing gp160 of HIV-1, cytotoxic T cells (CD8+ CD4-) were induced under restriction of class I MHC antigen. Iscoms containing the fusion protein of measles virus induced T cell clones in mice whereof one, after adoptive transfer, protected mice against intracerebral challenge infection. Protective immunity against Epstein-Barr virus (EBV)-induced tumor formation by iscoms containing gp350 of EBV has been elicited in cotton-top Tamerin monkeys. Protective immunity has also been induced against several virus infections including feline leukemia virus and against parasites, i.e., Trypanosoma cruzi, in mice.

Adjuvants, Immunologic↗
PubMed1990

Vaccination of Balb/c mice against enteroviral mediated myocarditis.

A non-virulent strain of Coxsackie B3 (CB3) virus was used to produce a subunit vaccine. It contains the capsid proteins VP1, 2, 3 and probably 4 and can be made RNA-free. It is based on the ISCOM technology ensuring non-toxic properties and good adjuvant effect. Vaccinated animals at doses above 16 ng were completely protected from mortality when challenged with a myocarditic strain of CB3. Histologically no inflammatory lesions were found in the heart. This was corroborated using immune histological techniques with monoclonal antibodies against lymphocyte subsets. Even at a dose of 0.16 ng a delayed mortality was observed. Neutralizing antibody titres rose to 512, thus ensuring a circulating level well above that considered protective. It is suggested that vaccination might be a possible way of prophylaxis for myocarditis and even dilated cardiomyopathy, the latter presently being the chief cause of heart transplantation. By persistence or triggering of autoimmune phenomena Coxsackie virus is incriminated as the first step in pathogenesis.

Animals↗
PubMed1990

Iscoms.

The common problem for defined purified antigens or antigen determinants has been to make them immunogenic regardless of whether they are produced conventionally, produced as cloned genetechnology products or chemically synthesized. The first problem is to get the protective antigen into a submicroscopic particle where the antigen is presented in several copies, i.e. as a multimer. For some antigens it seems also necessary to enhance the immunogenicity with an adjuvant. The immunostimulating complex (iscom) was created to fulfil these criteria by assembling antigens in a multimeric form on a matrix with built-in adjuvant to form a particle. The components are held together by hydrophobic interactions. The iscom has turned out to be highly immunogenic, inducing high antibody mediated and cell-mediated immunity including cytotoxic T cell response to influenza virus. In a mouse model iscoms containing influenza virus envelope proteins induced protective immunity by one intranasal administration. Protective immunity was also induced to a retrovirus--feline leukemia virus. In a monkey model system iscoms containing gp360 of Epstein-Barr virus induced protection to induction of tumours. Iscoms have also been used as carriers for small molecules such as oligopeptides, which combination appeared to be highly immunogenic.

Adjuvants, Immunologic↗
PubMed1990

Characterization of immunostimulating complexes (ISCOMS) of HIV-1.

HIV-1, strain HTLV-III, propagated in H9 cells and purified by sucrose gradient centrifugation, was used as native antigen source for the preparation of immunostimulating complexes, HIV-iscoms. The major antigen detected in the iscom was the cell-derived HLA-DR, which readily could be removed from the virus lysate by immunosorbent. In the iscoms the HIV structural proteins MA p17, p55 and TM gp41 were identified; SU gp120 was present in only minute amounts in the virus lysate. The iscom particles appeared well preserved after freeze drying with a round shape, approximately 35 nm in diameter, comprising morphological subunits, assembled with icosahedral symmetry. Immunization experiments in mice reflected the antigen content of the iscoms. High antibody response was induced to HLA-DR in non-depleted iscoms. Major humoral responses were observed to the viral structural proteins MA p17, CA p24, p55, and also to TM gp41. A low or negligible antibody response to SU gp120 was induced by the HIV-iscoms. The negligible response was, however, overcome by the addition of recombinant gp160 to the virus lysate prior to formation of iscoms, resulting in a preparation evoking a clear serum antibody to gp160.

Animals↗
PubMed1990

Neutralizing cross-reactive and non-neutralizing monoclonal antibodies to HIV-1 gp120.

Amino acid sequences inducing neutralizing antibodies to HIV-1 were sought. Murine monoclonal antibodies (MAbs) were characterized by their reactivity with the envelope precursor gp160 or the Escherichia coli recombinant DNA products pB1 and pE3 representing the carboxy- and amino-terminal halves of mature envelope gp120. Fine mapping of the MAb determinants was performed using defined 15-mer synthetic peptides spanning the entire envelope gp120 region of HIV-1. One group of MAbs recognizes epitopes (amino acids 304-323) occurring in a small region with variable and conserved amino acid sequences of gp120. These MAbs mediate neutralization of the HIV-1 strain HTLV-IIIB (HIV-1IIIB) which was used for immunization. Nine out of 11 primary HIV-1 isolates were neutralized well or moderately well. In addition, prominent serological reactivity was noted with peptide sequences of strains of various European or American origins, but not with two HIV-1 strains of African origin. The cross-reactivity contrasts with previously described type-specific reactions to other sequences of this region. The reactivity to the short conserved site GPGR with its flanking amino acids may explain the broad sequence cross-reactivity seen with our neutralizing MAbs. Two other MAbs recognize conserved epitopes (amino acids 79-103) situated in the amino-terminal region of gp120. These MAbs did not neutralize HIV-1IIIB.

Amino Acid Sequence↗
PubMed1990

An experimental influenza subunit vaccine (iscom): induction of protective immunity to challenge infection in mice after intranasal or subcutaneous administration.

An experimental influenza virus (A/PR/8/34(H1N1] vaccine was tested and evaluated in mice. The mice were inoculated once or twice intranasally or subcutaneously with 1 or 10 micrograms of iscoms prior to challenge with high dose of live virus. It was demonstrated that two intranasal administrations were as efficient as two s.c. administrations, both routes inducing high levels of antibody and protection against challenge infection. With a one-dose regimen, the s.c. route induced a somewhat higher antibody response than the intranasal route; this might be explained by technical difficulties connected with an intranasal administration.

Administration, Intranasal↗
PubMed1990

Iscom (immunostimulating complex) vaccines containing mono- or polyvalent pili of enterotoxigenic E. coli; immune response of rabbit and swine.

Iscom (immunostimulating complex) vaccines were prepared to contain K88ab, K88ac, K99 and 987P pili (fimbriae) of enterotoxigenic E. coli bacteria as monovalent or quadrivalent preparations. The iscoms injected into rabbits and into pigs elicited similar or higher immune response in both animal species than the oil adjuvanted vaccine containing about 5 times more of the same pilus protein. It is concluded that inclusion of pili into iscoms results in immunogenic preparations likely worth pursuing for vaccine production against enterotoxic colibacillosis of newborn pigs. The iscoms did not induce local reaction at the injection sites in contrast to the oil adjuvanted vaccines.

Adjuvants, Immunologic↗
PubMed1990

Epstein-Barr virus (EBV) antigens processed and presented by B cells, B blasts, and macrophages trigger T-cell-mediated inhibition of EBV-induced B-cell transformation.

The ability of B cells, B blasts, and macrophages to present Epstein-Barr virion antigens to autologous T cells and trigger their capacity to inhibit Epstein-Barr virus-induced B-cell transformation was tested. Macrophages were as efficient as B cells and B blasts in presenting the virus to T lymphocytes. This function required antigen processing, because it was inhibited by chloroquine treatment and by fixation of the antigen-presenting cells immediately after viral exposure but not 18 h later. T cells exposed to the purified Epstein-Barr virus envelope antigen gp350 coupled to immunostimulating complexes also showed inhibitory function. These results suggest that recognition of processed virion antigens elicits the generation of T-cell-mediated inhibition of Epstein-Barr virus-induced B-cell transformation.

Antigens, Viral↗
PubMed1989

Inflammatory response and antigen localization following immunization with influenza virus ISCOMs.

The inflammatory response, antigen retention, and antigen localization was studied in mice after immunization with influenza virus glycoproteins presented in two physically defined forms--micelles and ISCOMS (immunostimulating complexes). Two hours after intraperitoneal injection, the proportion of polymorphonuclear leukocytes (PMNs) in peritoneal lavage cells increased from less than 1% to 82% in ISCOM-treated mice and from less than 1% to 41% of the total cell count in micelle-treated mice. For both treatment groups, the proportion of PMNs returned to around zero 24 h postimmunization. Total recovery of radioactive antigen was significantly greater (P less than 0.05) in ISCOM-treated than in micelle-treated mice at one, two, and eight days postinjection. At all times tested, animals given ISCOMs had significantly more radioactive antigen in their spleens than animals given micelles. By electron microscopy ISCOMs were found to attach externally to the plasma membrane or within phagosomes of macrophages in close association with the membranes.

Animals↗
PubMed1989

Analysis of the feline immune response to human myelin-associated glycoprotein.

Elucidation of the pathogenesis of demyelinating peripheral neuropathy associated with myelin-associated glycoprotein (MAG) binding IgM paraproteins requires an in vivo animal model of the syndrome. Multiple immunizations of cats with MAG in Freund's adjuvant did not produce an antibody response but four immunizations with MAG-iscom (Morein, B. et al. (1984) Nature, 308: 457-460) did induce IgM antibodies which bound to human MAG and cat peripheral nerve myelin. Despite the presence of antibody for a 13-month period, no neuropathy developed. At necropsy, the peripheral nerves were ultrastructurally normal and no antibody was detectable in the endoneurium. A competitive ELISA indicated that the cat and human IgM antibodies recognized different epitopes.

Animals↗
PubMed1989

Bovine leukaemia virus ISCOMs: biochemical characterization.

The glycoprotein gp51 of bovine leukaemia virus (BLV) has been included in an immunostimulating complex (ISCOM). The ISCOM was characterized biochemically in SDS-polyacrylamide gel electrophoresis showing the presence of proteins of estimated molecular weights of 50 and 30 kDa. Immunoblotting showed that gp51 was present in the ISCOM. The BLV-ISCOM had a S-value of 19 S and the electronmicrograph showed the cage-like structure as previously reported for other ISCOMs. About 17% of the total amount of gp51 in the cell culture fluid was recovered in the ISCOMs. The largest loss of gp51 was encountered during the sedimentation of the virus. An ELISA, utilizing monoclonal antibodies to defined epitopes for capture was developed to control the antigenicity of epitopes, e.g. those known to induce neutralizing antibodies. Using this device as a quality control for epitopes the following could be stated. First, ISCOMs prepared from virus solubilized with the non-ionic detergents Triton X-100 or MEGA did not react with neutralizing monoclonal antibodies. In contrast, ISCOMs prepared from virus solubilized with the non-ionic detergents Tween-20, Tween-80 or octyl glucoside did react with the neutralizing antibodies. Second, the neutralizing epitopes were better exposed in ISCOMs than the other epitopes of gp51. In a preliminary experiment it was shown that gp51 in ISCOMs was highly immunogenic.

Adjuvants, Immunologic↗
PubMed1989

Serological responses in cats vaccinated with FeLV ISCOM and an inactivated FeLV vaccine.

Various approaches have been considered for generation of effective and safe vaccines against retroviruses, including HIV, with limited success. In the present vaccination study, encompassing 137 household cats, we have composed an experimental ISCOM subunit vaccine containing gp70 of feline leukaemia virus (FeLV)--the external glycosylated envelope protein, and the transmembrane protein p15E, with a commercial available inactivated FeLV vaccine (Leukocell). The two vaccines were estimated to contain approximately the same amount of gp70 antigen and the cats were immunized three times according to the recommendations of the commercial vaccine. A control preparation not containing gp70 or p15E was also included. During the observation period of 200 days all cats remained healthy and no virus was isolated during the isolation attempts. The serological responses were measured in ELISA, membrane immunofluorescence (MIF) and virus neutralization (VN) tests. In contrast to the cats in the other groups almost all ISCOM-vaccinated cats responded by seroconversion or increased titres in the three tests. The development of specific antibodies to gp70 and p15E were confirmed in Western blot. These results clearly illustrate the potential of the ISCOM structure for the development of safe and effective vaccines against retroviruses.

Animals↗
PubMed1989

Formation and characterization of FeLV ISCOMs.

Immunostimulating complexes (ISCOMs) have been prepared from feline leukaemia virus (FeLV) envelope proteins. The ISCOMs were characterized biochemically in SDS-polyacrylamide gel electrophoresis showing the presence of proteins of estimated molecular weights of 15,000, 27,000 and 70,000. Immunoblotting showed that both the transmembrane protein p15E and the external glycoprotein gp70 (making up the gp85 protein) were present in the ISCOM. Furthermore, a degradation product of gp70 with an estimated molecular weight of 32,000 was identified in the immunoblot. The FeLV ISCOM was shown by electron microscopy to have the characteristic cage-like structure of an ISCOM with a mean diameter of 37 nm. About 10% of the total amount of gp70 in the culture fluid was recovered in the ISCOMs. The largest loss was encountered during the sedimentation of the virus. In a preliminary immunization experiment in mice the FeLV ISCOMs elicited after a booster gave a clear-cut immune response against gp70.

Animals↗
PubMed1989

Immune response to immunostimulatory complexes (ISCOMs) prepared from human immunodeficiency virus type 1 (HIV-1) or the HIV-1 external envelope glycoprotein (gp120).

In mice, immunostimulatory complexes (ISCOMs) prepared from HIV-1 B external envelope glycoprotein (gp120) induced 10-fold higher antibody titres than gp120 emulsified in depot adjuvant, as measured by enzyme-linked immunosorbent assay (ELISA). Rhesus monkeys immunized with gp120 ISCOMs produced precipitating and virus neutralizing antibody titres equivalent to those seen in HIV-infected chimpanzees and humans. After multiple immunizations with HIV-1 B gp120 ISCOMs, a rhesus monkey developed a neutralizing response to the HIV-1 isolates RF and MN, but not to the CC isolate. Antisera from ISCOM-immunized rhesus monkeys recognized gp120 on the membranes of HIV-1 B-infected H9 cells, indicating the preservation of epitope structure in the ISCOMs matrix.

Adjuvants, Immunologic↗
PubMed1989

Iscom of viral envelope proteins protects against Aujeszky's disease.

An immunostimulating complex (iscom) containing the envelope proteins of pseudorabies virus (PRV) was prepared and its efficacy was evaluated in two experiments on sheep. In the first experiment, sheep were intramuscularly (i.m.) or intradermally (i.d.) vaccinated with PRV iscom doses varying between 1 and 81 micrograms. The vaccination was repeated on Day 21 and the animals were exposed to challenge infection by subcutaneous inoculation of 1000 TCID50 of the virulent Phylaxia strain on Day 35 after first vaccination. In the second experiment, sheep were i.m. vaccinated with single doses of iscom varying between 1 and 27 micrograms and challenge-infected on Day 14. It was found that: (1) the i.d. administration of PRV iscom has no advantage over i.m. administration (2); a single dose of greater than or equal to 3 micrograms of PRV iscom provided protection against the disease. In immunoblots, viral proteins of molecular masses 120, 109, 55, 53 and 32 kDa were detected with the sera obtained from iscom-vaccinated and subsequently challenge-infected sheep, but not with sera from sheep which were iscom-vaccinated only. The above findings indicated that: (1) by using iscom technology, potent subunit vaccines can be prepared to prevent Aujeszky's disease; (2) the selective incorporation of viral envelope proteins into iscoms gives the opportunity to discriminate between iscom-vaccinated and naturally infected animals.

Adjuvants, Immunologic↗