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Results for “Vaccines, Subunit”

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PubMed2006

Efficacy and functionality of lipoprotein OprI from Pseudomonas aeruginosa as adjuvant for a subunit vaccine against classical swine fever.

Bacterial lipoproteins are potent stimulators of innate immune responses and can mediate humoral and cytotoxic T cell responses without additional adjuvants. OprI derived from Pseudomonas aeruginosa was tested in vitro and in vivo for its adjuvant potential in the context of a classical swine fever (CSF) subunit vaccine. OprI activated porcine monocyte-derived dendritic cells (MoDC), upregulating CD80/86 and MHC class II expression, as well as pro-inflammatory cytokines. OprI enhanced CSFV-antigen-specific lymphocyte proliferation and IFN-gamma release. An E2/NS3-based subunit vaccine adjuvanted with OprI stimulated specific immune responses and partial protection against CSFV infection. Although, a water-oil-water adjuvanted vaccine was more potent at protecting animals, this study demonstrates that OprI has immunostimulatory properties for porcine DC, and has potential as vaccine immunostimulant. Further studies are necessary to optimize antigen formulation enabling to translate the in vitro efficacy into a potent vaccine in vivo.

Adjuvants, Immunologic↗

PubMed2004

Incorporation of CpG oligodeoxynucleotide fails to enhance the protective efficacy of a subunit vaccine against Mycobacterium tuberculosis.

Vaccines which offer better protection than BCG are now badly needed for controlling tuberculosis infection throughout the world. Immunological adjuvants capable of inducing a TH1 type of protective response are necessary to augment the immune response, particularly in the case of subunit vaccines. It is now well established that oligodeoxynucleotides (ODN) containing cytidine phosphate guanosine (CpG) motifs enhance cell-mediated responses in vivo by increasing the production of the TH1 cytokines IL-12 and interferon gamma (IFNgamma). To determine if this would improve subunit vaccination of mice CpG ODN were added to a subunit vaccine consisting of the culture filtrate proteins (CFP) of Mycobacterium tuberculosis H37Rv. It was observed that although adding CpG ODN to the vaccines promoted substantially increased IFNgamma production by lymph node cells draining sites of inoculation, this failed to translate after aerosol challenge into any degree of enhancement of bacterial clearance in the lungs, influx of IFN-positive T cells, or changes in histopathology. These data suggest that the vaccine enhancing effects of CpG ODN are relatively transient.

Animals↗

PubMed1991

Efficacy of SIV/deltaB670 glycoprotein-enriched and glycoprotein-depleted subunit vaccines in protecting against infection and disease in rhesus monkeys.

Immunization with an inactivated whole-virus vaccine is highly effective in preventing lentivirus infection. The viral protein(s) essential to the induction of protective responses, however, have not been identified. To define the role of virion components in the induction of protective immunity, we evaluated the efficacy of glycoprotein-enriched and glycoprotein-depleted simian immunodeficiency virus (SIV) subunit vaccines prepared by lentil-lectin affinity chromatography of gradient-purified virions using the immunization and challenge regimen previously found successful with an inactivated whole-virus vaccine. Infection was determined by successful recovery of virus, the induction of SIV-specific antibody responses, and infection of naive recipients by inoculation with lymph-node-derived lymphocytes from the vaccinates. Immunization with the glycoprotein-enriched preparation prevented infection in two out of four monkeys, whereas the glycoprotein-depleted vaccine failed to prevent infection in all four vaccinates tested. However, the glycoprotein-depleted vaccine appeared to moderate the progression of SIV-induced disease compared with non-immunized infected control monkeys inoculated with the same challenge dose. These data suggest that subunit vaccines containing sufficient quantities of viral glycoproteins can protect against SIV infection, whereas subunit vaccines composed predominantly of viral core proteins cannot. The development of effective vaccines against HIV infection should include studies on the optimum presentation of the viral envelope glycoproteins to produce long-term broadly protective immune responses.

Animals↗

PubMed2001

Peptide-based subunit vaccines against pre-erythrocytic stages of malaria parasites.

Malaria currently ranks among the most prevalent infections in tropical and sub-tropical areas throughout the world with relatively high morbidity and mortality particularly in young children. The widespread occurrence and the increased incidence of malaria in many countries, caused by drug-resistant parasites (Plasmodium falciparum and P. vivax) and insecticide-resistant vectors (Anopheles mosquitoes), indicate the need to develop new methods of controlling this disease. Experimental vaccination with radiation-attenuated sporozoites can protect animals and humans against the disease, demonstrating the feasibility of developing an effective malaria vaccine. However, vaccines based on radiation-attenuated sporozoites are not feasible for large scale application due to lack of in vitro culture system. Therefore, the development of peptide-based subunit vaccines has been undertaken as an alternative approach. Synthetic peptides containing defined B- and T-cell epitopes of different antigens expressed in sporozoites and/or liver stages have been used as subunit vaccines in experimental animal models. They have been shown to be highly immunogenic and capable of inducing protective immunity mediated by antibodies, as well as CD4+ and CD8+ T-cells.

Animals↗

PubMed2002

Passive transfer of serum antibodies induced by BBG2Na, a subunit vaccine, in the elderly protects SCID mouse lungs against respiratory syncytial virus challenge.

Respiratory syncytial virus (RSV) is responsible for severe low respiratory tract infections in young infants and the elderly. To investigate whether BBG2Na, a recombinant subunit vaccine comprising aa 130-230 of the RSV G protein, induced protective Abs in subjects over 60 years during phase II clinical trial, pre- and postimmunization sera of individuals immunized with BBG2Na or placebo were transferred into SCID mice before RSV challenge. These sera dose-dependently reduced lung RSV titers. However at some points of serial dilutions, postimmunization sera of BBG2Na-immunized subjects only were significantly more efficient than the corresponding preimmunization sera, in agreement with the induction of an increased Ab response against multiple epitopes on RSV-A G protein. Thus, BBG2Na is immunogenic in the elderly and confers passive protection in mice after serum transfer. To our knowledge, this is the first description of protective Abs induced by a subunit vaccine in human.

Administration, Intranasal↗

PubMed1999

An experimental multivalent bovine virus diarrhea virus E2 subunit vaccine and two experimental conventionally inactivated vaccines induce partial fetal protection in sheep.

The primary aim of a bovine virus diarrhea virus (BVDV) vaccine is to prevent transplacental transmission of virus. We studied the efficacy of two experimental conventionally inactivated vaccines, based on BVDV strain Singer and containing a different antigen amount, against three antigenically different BVDV strains in a vaccination-challenge experiment in sheep. We also studied the efficacy of an experimental multivalent E2 subunit vaccine against four antigenically different BVDV strains. The vaccine contained the glycoproteins E2 of BVDV strains that belong to antigenic groups IA, IB and II. All three vaccines induced neutralizing antibodies against all challenge strains. Only the conventional vaccine that contained the highest antigen amount induced complete protection against homologous challenge. Neither of the conventional vaccines provided complete protection against heterologous challenge. The multivalent subunit vaccine induced partial protection against the homologous challenge strains. However, the immune response did inhibit virus replication in ewes, as shown by the results of the virus titrations.

Abortion, Veterinary↗

PubMed2005

Antigenicity, immunogenicity, and protective efficacy of Plasmodium vivax MSP1 PV200l: a potential malaria vaccine subunit.

The merozoite surface protein 1 (MSP-1) is expressed in all Plasmodium species and is considered a major malaria vaccine candidate. We found that MSP-1 from Plasmodium vivax (PvMSP-1) contains a region of significant sequence homology with the 190L subunit vaccine derived from the P. falciparum MSP-1. The fragment, termed Pv200L, was expressed as a recombinant protein in Escherichia coli (rPv200L) and used to asses its immunologic relevance as a vaccine target. A cross-sectional, seroepidemiologic study conducted in Buenaventura, Colombia showed that 52.2% (95% confidence interval [CI] = 39.8-64.3) of individuals previously exposed to P. vivax and 72.8% (95% CI = 61.8-82.1) of P. vivax-infected patients had IgG antibodies to rPv200L. Immunization of BALB/c mice and Aotus monkeys induced IgG antibodies (titer > 10(6)) that cross-reacted with P. vivax parasites. Immunized monkeys displayed partial protection against a challenge with P. vivax blood stages. Our results suggest that Pv200L is a new malaria vaccine subunit and deserves further testing.

Amino Acid Sequence↗

PubMed2001

Advances and prospects for subunit vaccines against protozoa of veterinary importance.

Protozoa are responsible for considerable morbidity and mortality in domestic and companion animals. Preventing infection may involve deliberate exposure to virulent or attenuated parasites so that immunity to natural infection is established early in life. This is the basis for vaccines against theilerosis and avian coccidiosis. Vaccination may not be effective or practical with diseases, such as cryptosporidiosis, that primarily afflict the immune-compromised or individuals with an incompletely developed immune system. Strategies for combating these diseases often rely on passive immunotherapy using serum or colostrums containing antibodies to parasite surface proteins. Subunit vaccines offer an attractive alternative to virulent or attenuated parasites for several reasons. These include the use of bacteria or lower eukaryotes to produce recombinant proteins in batch culture, the relative stability of recombinant proteins compared to live parasites, and the flexibility to incorporate only those antigens that elicit "protective" immune responses. Although subunit vaccines offer many theoretical advantages, our lack of understanding of immune mechanisms to primary and secondary infection and the capacity of many protozoa to evade host immunity remain obstacles to developing effective vaccines. This review examines the progress made on developing recombinant proteins of Eimeria, Giardia, Cryptosporidium, Toxoplasma, Neospora, Trypanosoma, Babesia, and Theileria and attempts to use these antigens for vaccinating animals against the associated diseases.

Animals↗

PubMed2005

Mycobacterial 70 kD heat-shock protein is an effective subunit vaccine against bovine paratuberculosis.

Paratuberculosis is a chronic granulomatous inflammation of the small intestine of cattle and other ruminants, caused by infection with Mycobacterium avium ssp. paratuberculosis (MAP). The disease can be found in ruminant herds worldwide, causing substantial economic losses at farm level due to premature culling and production losses. In previous studies, it has been shown that immune responses to recombinant MAP Hsp70 proteins were predominantly cell mediated. As protective immunity to the intracellular mycobacterial pathogens is thought to be cell-mediated in origin, we have studied the use of a recombinant MAP Hsp70 as a subunit vaccine in cattle experimentally infected with MAP. The results of the current study demonstrate that recombinant MAP Hsp70 can be successfully used as a subunit vaccine against bovine paratuberculosis, significantly reducing shedding of bacteria in feces during the first 2 years following experimental infection.

Animals↗

PubMed2002

The protective efficacy of a recombinant VP2-based African horsesickness subunit vaccine candidate is determined by adjuvant.

We previously demonstrated that soluble baculovirus-expressed African horsesickness virus (AHSV) serotype 5 VP2 protein (AHSV5 rVP2) elicits neutralising antibodies in guinea pigs. We have now determined the immunogenicity of soluble AHSV5 rVP2 in horses when administered in three different adjuvant types, ISA-50, aluminium phosphate and different saponin preparations. Doses of 10 and 50microg of rVP2 administered with saponin induced full protection to a lethal challenge, albeit with dose-related side effects. The results establish that soluble rVP2 is the biologically active form and that it can induce complete protection when it is delivered with saponin adjuvants. We conclude that the use of the soluble biologically active form of AHSV rVP2 and the choice of adjuvant will be crucial factors in determining efficacy, safety and the production cost of recombinant AHSV subunit vaccines.

Adjuvants, Immunologic↗

PubMed1999

A novel influenza subunit vaccine composed of liposome-encapsulated haemagglutinin/neuraminidase and IL-2 or GM-CSF. I. Vaccine characterization and efficacy studies in mice.

The aim of this study was to improve the potency of the currently used influenza subunit vaccines, which are of relatively low efficiency in high-risk groups. Influenza A virus (Shangdong/9/93) haemagglutinin/neuraminidase (H3N2), granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-2 (IL-2) were encapsulated, each separately or combined, in multilamellar vesicles composed of dimyristoyl phosphatidylcholine. BALB/c mice were immunized once, i.p. or s.c., with 0.05-2.0 microg HN administered either as free antigen (F-HN), adsorbed to aluminum hydroxide (Al-HN), or encapsulated in liposomes (Lip-HN), separately or together with 1 x 10(2)-4.5 x 10(4) units of free or encapsulated cytokines. Serum antibodies were assayed on days 11-360 by the haemagglutination-inhibition (HI) test and ELISA. Protective immunity against intranasal virus challenge was determined at 9-14 months post-vaccination. The following results were obtained: (1) The efficiency of encapsulation in liposomes was 95, 90 and 38% for HN, IL-2 and GM-CSF, respectively, and the liposomal preparations were highly stable as an aqueous dispersion for > 2 months at 4 degrees C. (2) Following immunization with 0.5 microg Lip-HN, there was an earlier, up to 50-fold stronger, and 3-5 times longer response than that obtained with nonliposomal HN. (3) Coimmunization with free cytokines further increased the response 2-20 times and the two cytokines had an additive effect. (4) Liposomal cytokines were 2-20 times more effective than the free cytokines and their stimulatory effect was more durable. (5) A 100% seroconversion (HI titer > or = 40) was achieved with only 10-25% of the routinely used antigen dose, by encapsulating either antigen or cytokine. (6) The level of protection following vaccination with the combined liposomal vaccines was 70-100% versus 0-25% in mice immunized with Al-HN alone, and no toxicity was observed. In conclusion, our animal experiments show that the liposomal vaccines are superior to the currently used influenza vaccines, increasing the response by 2-3 orders of magnitude in mice. This approach may also prove valuable for subunit vaccines against other microorganisms.

Aluminum Hydroxide↗

PubMed2006

Identification of candidates for a subunit vaccine against extraintestinal pathogenic Escherichia coli.

Extraintestinal pathogenic Escherichia coli (ExPEC) strains cause a large spectrum of infections. The majority of ExPEC strains are closely related to the B2 or the D phylogenetic group. The aim of our study was to develop a protein-based vaccine against these ExPEC strains. To this end, we identified ExPEC-specific genomic regions, using a comparative genome analysis, between the nonpathogenic E. coli strain K-12 MG1655 and ExPEC strains C5 (meningitis isolate) and CFT073 (urinary tract infection isolate). The analysis of these genomic regions allowed the selection of 40 open reading frames, which are conserved among B2/D clinical isolates and encode proteins with putative outer membrane localization. These genes were cloned, and recombinant proteins were purified and assessed as vaccine candidates. After immunization of BALB/c mice, five proteins induced a significant protective immunity against a lethal challenge with a clinical E. coli strain of the B2 group. In passive immunization assays, antigen-specific antibodies afforded protection to naive mice against a lethal challenge. Three of these antigens were related to iron acquisition metabolism, an important virulence factor of the ExPEC, and two corresponded to new, uncharacterized proteins. Due to the large number of genetic differences that exists between commensal and pathogenic strains of E. coli, our results demonstrate that it is possible to identify targets that elicit protective immune responses specific to those strains. The five protective antigens could constitute the basis for a preventive subunit vaccine against diseases caused by ExPEC strains.

Animals↗

PubMed1990

Evaluation of a HTLV-1 subunit vaccine in prevention of experimental STLV-I infection in Macaca nemestrina.

Pig-tailed macaques were vaccinated with a human T-cell lymphotropic virus type I (HTLV-I) subunit vaccine. Vaccinates and controls were challenged with simian T-cell lymphotropic virus type I (STLV-I)-infected cells. Vaccination yielded antibody responses to HTLV-I and STLV-I gag and env precursors. Controls developed HTLV-I and STLV-I antibody to gag and tax protein. Immunization produced syncytium inhibiting antibody and cellular cytotoxicity to virus-infected cells. Reverse transcriptase activity was present in control macaques only, implying that the subunit vaccine was protective against STLV-I infection.

Animals↗

PubMed2005

A subunit vaccine against hemorrhagic enteritis adenovirus.

Hemorrhagic enteritis virus (HEV) is an adenovirus that infects turkeys and causes immunosuppression and mortality. The virus used for the inactivated vaccine is extracted from spleens of infected turkeys, since its propagation in tissue cultures or embryonated eggs is unsuitable for mass production. The aim of this study was to develop a subunit vaccine based on a capsid protein of the virus. The knob protein, together with an adjacent part of the shaft domain pertaining to the fiber protein of HEV, was expressed in Escherichia coli and tested as a vaccine. Vaccination with this recombinant protein conferred protection against challenge in controlled and in floor-pen experiments. This finding suggests that the knob protein may be used as safe and efficient vaccine against hemorrhagic enteritis of turkeys. The possibility that the knob proteins of other adenoviruses may be protective and serve as vaccine is also discussed.

Adenoviridae Infections↗

PubMed2005

Influence of intron and exon splicing enhancers on mammalian cell expression of a truncated spike protein of SARS-CoV and its implication for subunit vaccine development.

The spike (S) protein of severe acute respiratory syndrome coronavirus (SARS-CoV) is important for vaccine development. A truncated S protein of the TW1 strain, STR2 (88 kDa), carrying three S fragments (S74-253, S294-739, and S1129-1255) was investigated to study the influences of intron and exon splicing enhancers to improve STR2 protein expression in mammalian cells. Our results showed that STR2 protein expression with the use of an 138 base-pair intron addition increased by 1.9-, 2.5-, and 4.1-fold in Vero E6, QBI-293A cells, and CHO/dhFr- cells (dihydrofolate reductase [dhfr] gene deficient CHO cells), respectively. Using the exon splicing enhancers, including a bidirectional splicing enhancer (BSE) or an exon splicing enhancer derived from the EDA alternative exon of the fibronectin gene (EDA ESE), were also found to increase STR2 protein expression in CHO/dhFr- cells by 1.7- and 2.6-fold. Nevertheless, combination of the intron and the exon splicing enhancers resulted in suppressing the intron-enhancing e STR2 protein expression in in CHO/dhFr- cells. Our studies also demonstrated the STR2 protein was mainly as the Endo H-sensitive glycoprotein (115 kDa) expressed in Vero E6, QBI-293A, and CHO/dhFr- cells. However, only a minor form of the Endo H-resistant glycoproteins ( approximately 130 kDa) was detected in CHO/dhFr- cells. Taken together, our results indicated that intron had a better enhancing effect on STR2 protein expression than exon splicing enhancers, and the expression of approximately 130 kDa STR2 glycoprotein was enhanced by the intron addition into the expression vector construct. Results of the present study can provide an optimal strategy to enhance SARS-CoV S protein expression in mammalian cells and may contribute to the development of SARS-CoV subunit vaccine.

Animals↗

PubMed2004

Evaluation of immunogenicity and protective efficacy of a Microsporum canis metalloprotease subunit vaccine in guinea pigs.

In order to identify protective immunogens against Microsporum canis infection, a purified recombinant keratinolytic metalloprotease (r-MEP3) was tested as a subunit vaccine in experimentally infected guinea pigs. Both humoral and cellular specific immune responses developing towards r-MEP3 were evaluated, by enzyme-linked immunosorbent assay and by in vitro lymphocyte transformation tests respectively. Vaccination induced a strong antibody response, and a significant but transient lymphoproliferative response against the protein. However, the protocol failed to prevent fungal invasion or development of dermatophytic lesions. These results show that under the present experimental conditions, r-MEP3 specific antibodies are not protective against a challenge exposure. They also suggest that in the same model, the induction of cell-mediated immunity towards r-MEP3 is not sufficient, indicating the need for further research in the field of specific immune mechanisms involved in M. canis dermatophytosis.

Animals↗

PubMed1986

Evaluation of a diagnostic antigen for the detection of Aujeszky's disease virus-infected subunit-vaccinated pigs.

An early virus protein complex that is found in the maintenance medium of Aujeszky's disease (AD) virus-infected cells was evaluated as a subunit diagnostic antigen (SUDA) in the enzyme-linked immunosorbent assay (ELISA). This antigen was found in purer form and in larger quantities for up to 12 h post-infection in the maintenance medium of AD virus-infected MDBK cell cultures than in the maintenance medium of virus-infected porcine Fallopian tube (PFT) and PK1a cell cultures. The SUDA was shown to be compatible with a lectin-derived subunit vaccine by the absence of positive ELISA reactions for antibody to this antigen in 25 AD virus-free subunit-vaccinated pigs. Following virus challenge, all fo 24 surviving vaccinated pigs seroconverted to SUDA within 10 days. Compatibility with the vaccine was further demonstrated by the absence of positive ELISA reactions for antibody to SUDA in 12 pigs that received five or six consecutive vaccine doses at 3-wk intervals. The sensitivity of the ELISA with SUDA was demonstrated by the detection of antibody in virus-infected vaccinated and non-vaccinated pigs for at least 15 and 22 weeks, respectively, following exposure to virus. The SUDA was also economical: it was calculated that 8000-14 000 tests could be run with the antigen present in the maintenance medium of one 850 cm2 plastic tissue culture roller bottle of virus-infected MDBK cells.

Animals↗

PubMed1984

The evaluation of a lectin-agarose based subunit vaccine and complementary diagnostic antigen for Aujeszky's disease (pseudorabies) in the pig.

Eleven out of 25 pigs were immunized with a lectin--agarose based subunit vaccine for Aujeszky's disease (AD). The vaccine was prepared by extracting protective antigens from a non-ionic detergent (Triton-X-100) extract of AD virus-infected PK-la cells with Lens culinaris agglutinin immobilized on agarose beads. Two groups of 3 and 4 pigs received 2 doses of vaccine each containing 426 micrograms of adsorbed protein. Two groups of 2 pigs each received 2 vaccine doses containing either 23 or 33 micrograms of adsorbed protein. All vaccinated pigs survived a nasal challenge of 10(8.5) PFU of virulent AD virus while 13 out of 14 (93%) uninoculated controls died between Days 5 and 9 post challenge. This immunizing preparation qualified as a practical subunit vaccine because pigs were protected with relatively small amounts of protective antigen while at the same time remained free of detectable antibody to a complementary diagnostic antigen. This antigen was obtained in relatively pure form from the maintenance medium of virus-infected cells 4 h post-inoculation. In addition both high and low dose vaccinates failed to produce detectable antibody to at least one other antigen complex. The composition of Lens culinaris agglutinin (LCA) and Ricinus communis agglutinin (RCA)-purified AD viral antigen preparations were also compared by crossed immunoelectrophoretic techniques. Both preparations contained two antigen complexes and two individual antigens in common. Each preparation also contained its own unique antigen complex. The RCA purified antigen preparation also contained small quantities of a single antigen that was not detectable in the LCA antigen preparation.

Adsorption↗