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PubMed2005

Low titer maternal antibodies can both enhance and suppress B cell responses to a combined live attenuated human rotavirus and VLP-ISCOM vaccine.

We investigated effects of low titer (Lo) circulating MatAb on protection and immunogenicity of attenuated (Att) human rotavirus (HRV) priming and 2/6-virus-like particle (VLP)-immunostimulating complex (ISCOM) boosting (AttHRV/VLP) or VLP-ISCOM alone vaccines. LoMatAb had both enhancing and suppressing effects on B cell responses, depending on tissue, antibody isotype and vaccine. Differential effects of LoMatAb on IgA responses in different tissues suggest that LoMatAb did not suppress induction of IgA effector and memory B cells but impaired homing of these cells to secondary lymphoid or effector tissues, reducing IgA antibody secreting cells and antibodies at these sites. The AttHRV/VLP vaccine partially overcame LoMatAb suppression, conferred moderate protection against virulent HRV (as measured by reduced viral shedding and diarrhea) and represents a new candidate for rotavirus vaccines for both humans and animals.

Adjuvants, Immunologic↗
PubMed1999

Comparison of the IFAT and Iscom-ELISA response in bovine foetuses with Neospora caninum infection.

The study was carried out to evaluate the efficacy of foetal serology in the diagnosis of Neospora-associated bovine abortions. Fluids from 14 foetuses of cows with confirmed neosporosis (Group A), seven foetuses with confirmed bovine viral diarrhoea virus (BVD infection) (Group B) and 11 aborted foetuses without demonstrable infection (Group C) were examined. The age of the foetuses ranged from 4.5 months to 9 months. Albumin concentration (measured by Rocket Immunoelectrophoresis) was not significantly different in Group A compared with that in both Groups B and C, while that in Group B was significantly lower than in Group C. Levels of total IgG ranged from 0.01 to 1.78 (mg IgG) ml(-1) measured by single radial immunodiffusion technique. A measurable level of total IgG was found in all foetuses from Groups A and B, with no significant difference between levels in the two groups. Only one foetus in Group C had a detectable level of IgG. All foetuses in Group A had a specific IgG response (titre> or = 20) against Neospora caninum using the IFAT, while no positive responses in IFAT were found in Groups B and C. Measurement of specific IgG1 and IgG2 by Iscom-ELISA showed one and three false-negative results, respectively, in Group A. The IgG1 and IgG2 response in Group A was correlated according to the Spearman test (r = 0.66). Increasing age of the foetuses correlated significantly with the foetal IgG concentration, the specific IgG and IgG1 + IgG2. On the basis of the results obtained, it was concluded that the IFAT with a cut-off titre of 1:20, was a specific method for diagnosis of neosporosis in foetuses older than 4.5 months. The Iscom-ELISA also showed promising results as a method for screening specific antibodies against N. caninum in foetal fluid.

Abortion, Veterinary↗
PubMed1998

A mucosal IgA response, but no systemic antibody response, is evoked by intranasal immunisation of dogs with Echinococcus granulosus surface antigens iscoms.

The search for protective antigens of intestinal parasites is conditioned by the methodology used to induce a relevant local immune response against them. The present work describes the use of immuno stimulating complexes (iscoms) from tegumental antigens from protoscoleces (PSC) of the cestode Echinococcus granulosus as immunogens in dogs by the intranasal route. It also describes the evaluation of the immune response evoked at the antibody level (systemically and at a distant mucosal location) as well as at the level of antibody secreting cells in peripheral blood. Iscoms from both E. granulosus tegumental antigens and hen ovalbumin (OVA), given at 50 microg doses by intranasal route, evoked significant secretory IgA antibody responses detected in saliva. Specific IgA secreting cells in peripheral blood also increased 10-20-fold, although transiently, after primary and secondary stimulation, whereas specific IgG secreting cells in peripheral blood were only detected in some individuals after the second antigenic exposure. Generation of immune responses at a related mucosal site provides evidence of localised immunity. No significant increase in systemic antibody titers of either IgM, IgG or IgA isotype was detected in plasma as a result of the immunisation. This fact could reflect that the nasopharyngeal mucosal associated lymphoid tissue of dogs is more strictly compartmentalised than that of other mammals.

Adjuvants, Immunologic↗
PubMed1998

Enhanced immune responses and resistance against infection in aged mice conferred by Flu-ISCOMs vaccine correlate with up-regulation of costimulatory molecule CD86.

Ageing is associated with a decline in immune function and our primary objective is to 'reverse' age-related decline in protective immune responses to vaccination by formulating vaccines in appropriate delivery systems. In this paper, we demonstrate that influenza vaccine formulated as ISCOMs is highly immunogenic and confers protection in aged mice, when compared to current influenza vaccine. The enhanced protection conferred by Flu-ISCOMs in aged mice correlates with the up-regulation of co-stimulatory molecule, CD86 (B7.2) and to a lesser extent, CD80 (B7.1) expression on antigen presenting cells.

Aging↗
PubMed1999

ISCOM vaccine induced protection against a lethal challenge with a human H5N1 influenza virus.

Recently avian influenza A viruses of the H5N1 subtype were shown to infect humans in the Hong Kong area, resulting in the death of six people. Although these viruses did not efficiently spread amongst humans, these events illustrated that influenza viruses of subtypes not previously detected in humans could be at the basis of a new pandemic. In the light of this pandemic threat we evaluated and compared the efficacy of a classical non-adjuvanted subunit vaccine and a vaccine based on immune stimulating complexes (ISCOM) prepared with the membrane glycoproteins of the human influenza virus A/Hong Kong 156/97 (H5N1) to protect roosters against a lethal challenge with this virus. The ISCOM vaccine induced protective immunity against the challenge infection whereas the non-adjuvanted subunit vaccine proved to be poorly immunogenic and failed to induce protection in this model.

Adjuvants, Immunologic↗
PubMed1997

Intranasal immunization of mice with Echinococcus granulosus surface antigens iscoms evokes a strong immune response, biased towards glucidic epitopes.

The present work describes the preparation and characterization of iscoms from tegumental antigens of Echinococcus granulosus protoscoleces, and their use as immunogens in mice by intranasal and subcutaneous routes. Iscoms given at 10 mg doses evoke a significant antibody response when administered i.n. and a strong and long lasting antibody response by s.c. route. The Ag administered i.n. in a non-adjuvanted form as a booster was not immunogenic. The i.n. route of immunization induced higher IgA serum titre in relation to IgG than the s.c. route and antisera of slightly higher avidity. Also, ten fold lower IgG2a/IgG1 and ten fold higher IgG3/IgG1 ratios were observed for the i.n. protocol compared to the s.c. one. Moreover, the mucosal route of immunization induced more efficiently antibodies of both isotypes directed to carbohydrate epitopes. The differences between immune response generated by i.n. and parenteral immunizations should be taken into consideration, particularly in those cases in which protective antigens are glycosylated.

Administration, Intranasal↗
PubMed2003

Experimental field trial with an immunostimulating complex (ISCOM) vaccine against contagious bovine pleuropneumonia.

The experimental field trial with an immunostimulating complex (ISCOM) vaccine has been an occasion to explore the role of a Th1 response in the pathogenesis caused by Mycoplasma mycoides subsp. mycoides small colony (MmmSC) and in immune protection. The ISCOM complex is known to promote Th1 response. Antibodies to MmmSC were detected by indirect enzyme-linked immunosorbent assay (ELISA) in the vaccinated cattle, although the levels were lower than in a previous study. No antibodies were detected by complement fixation test (CF). After the challenge infection, vaccinated animals developed CF antibody response. They showed significantly reduced mortality compared with controls. However, gross pathological and histopathological score for vaccinated animals was as high as for the non-vaccinated, characterized by a high inflammatory reaction with histopathology dominated by interlobular pneumonia with vasculitis.

Animals↗
PubMed1993

Immunogenicity in rabbits and monkeys of influenza ISCOMs conjugated with repeated sequences of the Plasmodium falciparum antigen Pf155/RESA.

Rabbits and monkeys were immunized with two fusion proteins, ZZ-M3 and ZZ-M5, coupled to pre-formed influenza virus membrane glycoprotein ISCOMs. The fusion proteins comprise two IgG-binding domains from staphylococcal protein A (ZZ) and repeated amino acid sequences from the C-terminal (M3) or central (M5) repeat regions of the Plasmodium falciparum antigen Pf155/RESA. The induced antibody responses were of long duration, could be efficiently boosted and were comparable to those obtained with Freund's Adjuvant. The produced antibodies reacted with M3, M5, protein A and the influenza glycoprotein, recognized Pf155/RESA and inhibited merozoite invasion in vitro. These results suggest that coupling of immunogens to pre-formed ISCOMs may be a basis for construction of multivalent subunit vaccines.

Amino Acid Sequence↗
PubMed1999

Comparison of immunity generated by nucleic acid-, MF59-, and ISCOM-formulated human immunodeficiency virus type 1 vaccines in Rhesus macaques: evidence for viral clearance.

The kinetics of T-helper immune responses generated in 16 mature outbred rhesus monkeys (Macaca mulatta) within a 10-month period by three different human immunodeficiency virus type 1 (HIV-1) vaccine strategies were compared. Immune responses to monomeric recombinant gp120SF2 (rgp120) when the protein was expressed in vivo by DNA immunization or when it was delivered as a subunit protein vaccine formulated either with the MF59 adjuvant or by incorporation into immune-stimulating complexes (ISCOMs) were compared. Virus-neutralizing antibodies (NA) against HIV-1SF2 reached similar titers in the two rgp120SF2 protein-immunized groups, but the responses showed different kinetics, while NA were delayed and their levels were low in the DNA-immunized animals. Antigen-specific gamma interferon (IFN-gamma) T-helper (type 1-like) responses were detected in the DNA-immunized group, but only after the fourth immunization, and the rgp120/MF59 group generated both IFN-gamma and interleukin-4 (IL-4) (type 2-like) responses that appeared after the third immunization. In contrast, rgp120/ISCOM-immunized animals rapidly developed marked IL-2, IFN-gamma (type 1-like), and IL-4 responses that peaked after the second immunization. To determine which type of immune responses correlated with protection from infection, all animals were challenged intravenously with 50 50% infective doses of a rhesus cell-propagated, in vivo-titrated stock of a chimeric simian immunodeficiency virus-HIVSF13 construct. Protection was observed in the two groups receiving the rgp120 subunit vaccines. Half of the animals in the ISCOM group were completely protected from infection. In other subunit vaccinees there was evidence by multiple assays that virus detected at 2 weeks postchallenge was effectively cleared. Early induction of potent type 1- as well as type 2-like T-helper responses induced the most-effective immunity.

AIDS Vaccines↗
PubMed1994

Quil A and ISCOMs as adjuvants for midgut membrane antigens of Boophilus microplus.

Quil A used with Boophilus microplus gut membrane antigen (GM) had a significant effect on antibody levels induced in sheep (P < 0.05) since GM alone did not induce a significant level of antibodies. Injection of a vaccine containing GM and Quil A, either subcutaneously or intramuscularly, induced similar levels of antibodies in sheep. However, Quil A injected subcutaneously induced acute inflammatory reaction. The amount of Quil A for use with GM was determined to be 1000 micrograms/ml. Immunostimulating complexes (ISCOMs) incorporating detergent-solubilized membrane midgut antigens (TX-GM) failed to induce an immune response in cattle without the addition of Quil A. The addition of Quil A to the ISCOMs containing TX-GM did not stimulate antibody responses greater than those stimulated by TX-GM plus Quil A, and protection in vaccinated cattle was 86% and 74%, respectively.

Adjuvants, Immunologic↗
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↗
PubMed1990

Immunogenic properties of ISCOM prepared with influenza virus nucleoprotein.

After covalent attachment of bacterial lipopolysaccharide to the nucleoprotein of influenza A virus, this water-soluble antigen could be incorporated firmly into ISCOM. This potent "immunostimulating complex" induced the production of high antibody titers in mice and could partially protect the animals from a lethal challenge infection. After immunization with ISCOM preparations NP-specific cytotoxic T cell activity could not be demonstrated.

Adjuvants, Immunologic↗
PubMed1990

Increased immunogenicity of a non-amphipathic protein (BSA) after inclusion into iscoms.

Bovine serum albumin (BSA) was used as a non-amphipathic model protein to be included into iscoms. Pretreatment at an acidic pH (2.5) was used to reveal hydrophobic regions, after which BSA could be integrated. In immunization experiments in mice the BSA iscoms induced long lasting and considerably higher serum antibody responses than non-treated monomeric BSA or BSA aggregated by acidic treatment.

Animals↗
PubMed1989

Experimental polyvalent ISCOMs subunit vaccine induces antibodies that neutralize human and bovine respiratory syncytial virus.

The purpose of the present study was to evaluate experimentally, in guinea-pigs, the immunogenicity of respiratory syncytial (RS) virus subunit vaccines. Immunostimulating complexes (ISCOMs), made from the surface proteins of both human (Long) and bovine (A-51908) RS strains adsorbed to the adjuvant Quil A, were assayed for their capacity to induce neutralizing antibodies, in comparison to experimental live virus vaccines. Serums from animals vaccinated with either the human or bovine RS subunit vaccines were equally efficient in neutralizing human or bovine RS virus. ISCOMs prepared with bovine RS virus proteins were significantly (p less than 0.05%) more efficient than their human counterpart, in inducing neutralizing antibodies, suggesting their greater potential as a subunit vaccine.

Adjuvants, Immunologic↗
PubMed1990

Protection against lethal equine herpes virus type 1 (subtype 1) infection in hamsters by immune stimulating complexes (ISCOMs) containing the major viral glycoproteins.

An experimental ISCOM vaccine has been prepared from gradient purified equine herpes virus type 1 (EHV-1). Radiolabelling studies demonstrated that this vaccine contained all the major viral glycoproteins in relative amounts similar to those found in non-detergent disrupted viral preparations. This EHV-1 ISCOM vaccine generated fully protective responses in hamsters challenged with an otherwise lethal dose of the hamster-adapted EHV-1 strain RACH.

Adjuvants, Immunologic↗
PubMed1992

Initiation of cytotoxic T-cell response and protection of Balb/c mice by vaccination with an experimental ISCOMs respiratory syncytial virus subunit vaccine.

Respiratory syncytial virus is an important human pathogen causing serious lower respiratory tract infections of children and elderly people. Previous studies on the development of experimental subunit vaccines either expressed by recombinant DNA technology or prepared from purified viral proteins absorbed on adjuvant (ISCOMs) have shown promise. The present work reports on the effectiveness of an experimental ISCOMs vaccine in initiating humoral and cell-mediated immune responses and in providing overall protection upon live virus challenge in Balb/c mice; results indicate that vaccination by the intramuscular route is more effective, even if vaccination by the intranasal route also significantly reduced virus shedding.

Animals↗
PubMed2003

Validation of a Neospora caninum iscom ELISA without a gold standard.

Neospora caninum is an intracellular parasite which causes abortion in cattle worldwide. One problem in the validation of the different methods for demonstration of this parasite is the lack of an appropriate gold standard. To validate an immunostimulating complex (iscom) enzyme-linked immunoassay (ELISA) used to detect antibodies to N. caninum, sera from 244 cattle in five Swedish dairy herds infected with N. caninum were analysed. The sera also were analysed by a standard indirect-fluorescent antibody test (IFAT). The results obtained by the two tests were compared using the Gibbs sampler. Gibbs sampling is a latent-class approach based on Bayesian statistics; neither test is assumed to be more correct in stating the true status of infection. The Gibbs sampler was run using both informative and non-informative prior probabilities. We also simulated different cut-offs in the iscom ELISA (providing data to inform selection of optimal cut-off values for different applications). The ELISA produced fewest incorrect test results over all at a cut-off value of 0.200. The sensitivity and specificity at this cut-off were 99 and 96%, respectively. The IFAT had a high specificity (99%) but a lower sensitivity (78%) than expected-confirming that the IFAT cannot be treated as a true gold standard. Sensitivity and specificity of the ELISA were presented in a two-graph receiver operating characteristic (TG-ROC) plot. Any cut-off between 0.150 and 0.300 will have both sensitivity and specificity > or =95%. Optical densities of < or =0.150 and > or =0.550 (or > or =0.350) were suggested as limits to rule out and rule in infection, respectively.

Animals↗
PubMed1988

Immunogenicity of liposomes and iscoms containing the major outer membrane protein of Neisseria gonorrhoeae: influence of protein content and liposomal bilayer composition.

The influences of Neisseria gonorrhoeae protein IB content and bilayer composition of liposomes and protein content of iscoms on immunogenicity were investigated. Changes in the protein content of liposomes did not influence the immunoglobulin G response, whereas the response was lowered when the amount of protein in iscoms was increased. Bilayer composition only influenced the primary immunoglobulin G response; immunological memory was not affected.

Animals↗