Biomedical subjects

G Riveau

Publications and source records attributed to G Riveau.

At least 37 records · Page 2Linked to original sources

PubMed1998

Homologous and heterologous protection after single intranasal administration of live attenuated recombinant Bordetella pertussis.

While single-dose mucosal immunization is best achieved by the use of attenuated live microorganisms, attenuation generally results in decreased immunogenicity. We attenuated Bordetella pertussis by the deletion of the pertussis toxin gene. A single intranasal administration of this strain protected against subsequent challenge as well as did the parent strain and better than immunization with commercial vaccine. Unexpectedly, this attenuation resulted in increased immunogenicity against the protective antigen filamentous hemagglutinin (FHA). In addition, immunogenicity was also enhanced against the Schistosoma mansoni Sm28GST genetically fused to FHA, resulting in protection against the parasite, as characterized by a reduction in worm burden and egg charge, after a single intranasal administration. Thus, attenuated recombinant B. pertussis strains are promising vectors for the simultaneous protection against pertussis and heterologous diseases by a single intranasal administration.

Adhesins, Bacterial↗

PubMed1998

Human IgE responses to rSm22.6 are associated with infection intensity rather than age per se, in a recently established focus of Schistomiasis mansoni.

In studies of schistosomasis mansoni-endemic communities, individuals with IgE responses to a 22 kD adult worm antigen (rSm22.6) suffered lower intensities of reinfection after treatment. It is of interest to define the factors that lead to the production of rSm22.6-specific IgE because it is a marker for resistant individuals and it may be involved in the development of resistance to reinfection. In endemic populations rSm22.6-specific IgE increases linearly with age. However, it is not possible to distinguish between age per se and 'history of infection' in endemic populations because individuals are exposed to the parasite at an early age. We have, therefore, quantified pre- and post-treatment isotype responses to rSm22.6 in a comparatively 'epidemic' Senegalese community where the patients were infected at different ages and where pre-treatment intensity of infection can be taken as a reasonable measure of antigen exposure. Post-treatment isotype responses to rSm22.6 correlated positively with pre-treatment intensities of infection but were not shown to be related to age. IgG1, IgG4 and IgE responses to rSm22.6 were significantly higher after treatment with the difference increasing with the pre-treatment level of infection. These results from a recently established focus of infection suggest that isotype responses to rSm22.6 are antigen-exposure dependent rather than dependent on age per se.

Adolescent↗

PubMed1998

Systemic and mucosal immune responses after intranasal administration of recombinant Mycobacterium bovis bacillus Calmette-Guérin expressing glutathione S-transferase from Schistosoma haematobium.

A major goal of current vaccine development is the induction of strong immune responses against protective antigens delivered by mucosal routes. One of the most promising approaches in that respect relies on the use of live recombinant vaccine carriers. In this study, Mycobacterium bovis BCG was engineered to produce an intracellular glutathione S-transferase from Schistosoma haematobium (Sh28GST). The gene encoding Sh28GST was placed under the control of the mycobacterial hsp60 promoter on a replicative shuttle plasmid containing a mercury resistance operon as the only selectable marker. The recombinant Sh28GST produced in BCG bound glutathione and expressed enzymatic activity, indicating that its active site was properly folded. Both intraperitoneal and intranasal immunizations of BALB/c mice with the recombinant BCG resulted in strong anti-Sh28GST antibody responses, which were enhanced by a boost. Mice immunized intranasally produced a mixed response with the production of Sh28GST-specific immunoglobulin G1 (IgG1), IgG2a, IgG2b, and IgA in the serum. In addition, high levels of anti-Sh28GST IgA were also found in the bronchoalveolar lavage fluids, demonstrating that intranasal delivery of the recombinant BCG was able to induce long-lasting secretory and systemic immune responses to antigens expressed intracellularly. Surprisingly, intranasal immunization with the BCG producing the Sh28GST induced a much stronger specific humoral response than intranasal immunization with BCG producing the glutathione S-transferase from Schistosoma mansoni, although the two antigens have over 90% identity. This difference was not observed after intraperitoneal administration.

Administration, Intranasal↗

PubMed1998

Bordetella pertussis filamentous hemagglutinin enhances the immunogenicity of liposome-delivered antigen administered intranasally.

In an attempt to increase the immunogenicity of mucosally delivered antigens, we incorporated the Bordetella pertussis filamentous hemagglutinin (FHA) adhesin into liposomes containing the glutathione S-transferase of Schistosoma mansoni (Sm28GST) as a model antigen. Outbred mice immunized twice intranasally with liposomes containing a constant suboptimal dose of Sm28GST and increasing doses of FHA produced anti-Sm28GST antibodies in a FHA dose-dependent manner. The addition of 3 microg of FHA to the liposomes induced more than 10-fold-higher anti-Sm28GST antibody titers, compared to those induced by liposomes without FHA. The presence of FHA did not alter the nature of the humoral immune response, and the sera contained anti-Sm28GST immunoglobulin G1 (IgG1), IgG2a, and IgG2b. However, anti-Sm28GST IgA was only detected when at least 3 microg of FHA was added to the preparation. These results show a promising potential for FHA to enhance the immunogenicity of mucosally administered antigens incorporated into liposomes.

Adhesins, Bacterial↗

PubMed1998

Glutathione S-transferases of 28kDa as major vaccine candidates against schistosomiasis.

For the development of vaccine strategies to generate efficient protection against chronic infections such as parasitic diseases, and more precisely schistosomiasis, controlling pathology could be more relevant than controlling the infection itself. Such strategies, motivated by the need for a cost-effective complement to existing control measures, should focus on parasite molecules involved in fecundity, because in metazoan parasite infections pathology is usually linked to the output of viable eggs. In numerous animal models, vaccination with glutathione S-transferases of 28kDa has been shown to generate an immune response strongly limiting the worm fecundity, in addition to the reduction of the parasite burden. Recent data on acquired immunity directed to 28GST in infected human populations, and new development to draw adapted vaccine formulations, are presented.

Animals↗

PubMed1998

Murine immune responses to Schistosoma haematobium and the vaccine candidate rSh28GST.

Longitudinal studies of Schistosoma haematobium infection in CBA mice revealed a progressive down-regulation of cellular immune responses, as measured by mitogenic and antigenic stimulation of in vitro lymphocyte cultures. Antigen-stimulated production of the Th1 cytokine IFN-gamma by splenocytes increased progressively up to 14 weeks post infection, (four weeks after the onset of parasite egg production), before declining swiftly. Levels of the Th2 cytokine IL-4 in the same cultures remained low until 14 weeks, after which they rose rapidly as IFN-gamma declined. High levels of IL-10 coincided with the peak in IFN-gamma production, suggesting a non Th2-restricted role for this cytokine. Both total and antigen-specific immunoglobulin production confirmed parasite egg deposition as being a major stimulus for host humoral responses. The S. haematobium infection failed to elicit detectable T cell responses to the antifecundity vaccine candidate rSh28GST. However, low levels of antibody were detectable in infected mouse serum and strong IgG and IgA production was induced by vaccination with rSh28GST plus adjuvant.

Animals↗

PubMed1997

Local transient induction of inflammatory cytokines after intranasal administration of recombinant Bordetella pertussis.

Inflammatory cytokines have been described to play a critical role in the orientation and amplification of the IgA immune response. In this study, we show that the intranasal administration of a Bordetella pertussis strain expressing the protective antigen glutathione-S-transferase of Schistosoma mansoni (Sm28GST) induced an inflammatory response in the lungs of mice, characterized by the production of inflammatory cytokines, such as Tumor Necrosis Factor alpha, Interleukin-6 and Transforming-Growth Factor beta. The production and the secretion of these cytokines in lung tissues were early and transient. Their presence was observed only during the first week after administration despite the persistence of the bacteria for 1 month. Two weeks after inoculation, Interleukin-10 secretion was detected in the lungs, which could explain the decrease in the production of inflammatory cytokines. These inflammation-regulating cytokines, induced in the lungs by the presence of the bacterial vector, could be part of the process generating the local immune response, in particular the anti-Sm28GST IgA response.

Administration, Intranasal↗

PubMed1997

Intradermal immunization of rats with plasmid DNA encoding Schistosoma mansoni 28 kDa glutathione S-transferase.

Direct administration of plasmid DNA encoding an antigen represents an attractive approach to vaccination against infectious diseases, particularly in developing countries where easy-to-handle and cost-effective vaccines are needed. We have investigated the potential of DNA immunization to induce a specific antibody response against Schistosoma mansoni, using plasmid-DNA encoding the protective antigen, S. mansoni 28 kDa glutathione S-transferase (Sm28GST). Since S. mansoni parasite penetrates into its host through the skin, this tissue was chosen for plasmid DNA delivery. Following plasmid DNA administration into the skin of rats, the parasite antigen was detected in skin cells by immunohistochemistry. Three administrations of 200 micrograms plasmid at 14 day intervals led to the induction of a long-lasting specific IgG antibody response in the sera of immunized rats, with a predominance of IgG2a and IgG2b subclasses. Sera of immunized animals were able to mediate antibody-dependent cellular cytotoxicity in vitro, leading to the specific killing of parasite larvae. A parasite challenge performed on plasmid DNA-immunized animals induced a strong and rapid boosting effect on the specific IgG antibody response. These results demonstrate the potential of genetic immunization via the skin with plasmid DNA encoding Sm28GST for inducing immune responses with protective patterns against an S. mansoni infection.

Animals↗

PubMed1997

Intranasal priming with recombinant Bordetella pertussis for the induction of a systemic immune response against a heterologous antigen.

One of the current goals in vaccine development is the noninvasive administration of protective antigens via mucosal surfaces. In this context, the gut-associated lymphoid tissues have already been extensively explored. Vaccination via the nasal route has only recently been the focus of intensive investigation, and no live vector specifically designed for the respiratory mucosa is yet available. In this study we show that intranasal administration of the recombinant Bordetella pertussis BPGR60, producing the Schistosoma mansoni 28-kDa glutathione S-transferase (Sm28GST) protective antigen fused to filamentous hemagglutinin, induces priming in mice for the production of serum antibodies. In addition to significant levels of anti-Sm28GST immunoglobulin A (IgA) antibodies, high levels of anti-Sm28GST serum antibodies were obtained after intranasal boost with the purified antigen or infection with S. mansoni following intranasal priming with BPGR60. These antibodies were of the IgG1, IgG2a, and IgG2b isotypes, suggesting a mixed immune response. No priming was observed in animals that had received nonrecombinant B. pertussis or purified Sm28GST, indicating specific priming by BPGR60. This priming was also evident in immune protection against S. mansoni challenge. Significant protection against worm burden and egg output was obtained in mice primed with BPGR60 and intranasally boosted with purified Sm28GST. A lower but still significant degree of protection against egg output was also obtained in mice infected with a single dose of BPGR60. These results indicate that intranasal administration of recombinant B. pertussis can prime for serum antibody responses against a foreign antigen and for heterologous protection.

Administration, Intranasal↗

PubMed1997

[Infectious etiology of diarrheal morbidity in a Senegalese region of high exposure to Schistosoma mansoni].

Endemic schistosomiasis due to Schistosoma mansoni has been observed in Richard-Toll (The Senegal River basin) in Senegal since 1990. Because of its high prevalence, schistosomiasis is assumed to be the cause of most cases of diarrhea observed in the region. The purpose of the present study carried out within the framework of the ESPOIR program for control of bilharziasis in the Senegal River region was to confirm the exact etiology of diarrhea in the region. A total of 109 subjects presenting diarrhea including 57 children under the age of 5 years were included in the study. In all cases, stool examination using appropriate techniques was performed to detect bacterial, viral, and parasitic agents. Schistosoma mansoni was identified in 47 cases (43.1%). Stool cultures were positive in 28 cases (25.6%) for Escherichia coli (n = 9), Shigella spp. (n = 18), and Salmonella spp. (n = 1). With regard to Shigella, a predominance of the Shigella dysenteriae type I stereotype (10/18) and a high incidence of co-infection involving Shigella spp. and Schistosoma was noted. Rotavirus infection was observed in 6 cases involving subjects under the age of 5 years. The relative incidence of the different infectious agents varied widely in function of age. This study in an endemic area of bilharziasis in Senegal demonstrates that Schistosoma mansoni should not be assumed to account for all cases of diarrhea occurring in the area.

Adolescent↗

PubMed1996

Induction of mucosal immune responses against a heterologous antigen fused to filamentous hemagglutinin after intranasal immunization with recombinant Bordetella pertussis.

Live vaccine vectors are usually very effective and generally elicit immune responses of higher magnitude and longer duration than nonliving vectors. Consequently, much attention has been turned to the engineering of oral pathogens for the delivery of foreign antigens to the gut-associated lymphoid tissues. However, no bacterial vector has yet been designed to specifically take advantage of the nasal route of mucosal vaccination. Herein we describe a genetic system for the expression of heterologous antigens fused to the filamentous hemagglutinin (FHA) in Bordetella pertussis. The Schistosoma mansoni glutathione S-transferase (Sm28GST) fused to FHA was detected at the cell surface and in the culture supernatants of recombinant B. pertussis. The mouse colonization capacity and autoagglutination of the recombinant microorganism were indistinguishable from those of the wild-type strain. In addition, and in contrast to the wild-type strain, a single intranasal administration of the recombinant strain induced both IgA and IgG antibodies against Sm28GST and against FHA in the bronchoalveolar lavage fluids. No anti-Sm28GST antibodies were detected in the serum, strongly suggesting that the observed immune response was of mucosal origin. This demonstrates, to our knowledge, for the first time that recombinant respiratory pathogens can induce mucosal immune responses against heterologous antigens, and this may constitute a first step toward the development of combined live vaccines administrable via the respiratory route.

Adhesins, Bacterial↗

PubMed1996

Neutralizing antibody responses elicited in mice immunized with recombinant bacillus Calmette-Guérin producing the Schistosoma mansoni glutathione S-transferase.

Schistosomiasis is a group of severe parasitic diseases, in humans and domestic animals, that are especially of importance in the developing world. No efficacious vaccine is currently available. However, Ab-mediated immune responses against the 28-kDa glutathione S-transferase of Schistosoma mansoni (Sm28GST) appear to be involved in protection. This Ag was produced in recombinant Mycobacterium bovis bacillus Calmette-Guérin (BCG). The recombinant protein bound glutathione and expressed enzymatic activity, indicating that the active site of Sm28GST was folded properly. Single i.v., i.p., s.c., or intranasal immunizations with rBCG in BALB/c mice resulted in significant anti-SM28GST Ab responses, which were enhanced by a booster dose. The Ab responses remained high for at least 1 yr after immunization. Analyses of the isotype profiles indicated that i.v. immunized mice produced high titers of anti-Sm28GST IgG2a, and less IgG2b and IgG1. Mice immunized by the s.c. route initially also produced high levels of IgG2a and low titers of IgG1 and IgG2b, but the titers of the latter two isotypes increased gradually thereafter, tending toward a mixed profile. Intraperitoneal immunization provided a mixed profile directly after the first administration. High titers of anti-Sm28GST Abs also corresponded to high levels of neutralization of the enzymatic activity. These results indicate that rBCG induces strong IgG1, IgG2a, and IgG2b, and neutralizing Ab responses against Sm28GST, which has been found to correlate with protection against S. mansoni in humans.

Animals↗

PubMed1996

Mucosal vaccination against schistosomiasis using liposome-associated Sm 28 kDa glutathione S-transferase.

A variety of experimental models have shown that immunization using the glutathione S-transferase from Schistosoma mansoni (Sm28GST) can induce protective immunity against this parasite. This immunity has been related to the production of Th2 type antibodies against the antigen in both mice and humans. The work presented in this paper describes the development of a mucosal immunization protocol using liposomes which is designed to promote production of specific antibodies of isotypes related to a Th2 immune response. The liposomes were multilamellar and composed of various synthetic phospholipid mixtures. The liposome vector was used to convey the Sm28GST antigen to gut associated lymphoid tissue. The association of the Sm28GST antigen with liposomes containing different lipid mixtures was initially studied. The degree of interaction of the antigen was found to increase with the hydrocarbon chain length of the lipids used. It was demonstrated that the protein was present on both the inner and the outer membranes of the liposome vesicles. It was also shown that the major epitopes of Sm28GST were accessible to specific antibodies, confirming a conservation of its main antigenic features. Additionally, enzymatic activity of the protein/liposome complex was also demonstrated, indicating a conservation of the tertiary structure of the protein. An optimal Sm28GST/ liposome complex was established and administered orally to mice. This treatment resulted in both a mucosal and systemic immune response to the antigen Sm28GST. This was demonstrated by the detection of specific IgA in gut washes and specific IgG1, IgG2b in sera. Immunization by Sm28GST/liposome complex followed by challenge with parasite showed that Sm28GST given orally in these conditions bore protective activity. This last result opens the possibility of mucosal vaccination against schistosomiasis.

Administration, Oral↗

PubMed1996

Influence of phospholipid composition on antibody responses to liposome encapsulated protein and peptide antigens.

The effect of phospholipid composition on mouse IgG antibody responses to liposomal bovine serum albumin (BSA), murine monoclonal antibody GK1.5 (anti-CD4) or a 21 amino acid peptide from the second conserved domain of HIV gp120 after s.c. administration, and on the IgA, IgE, and IgG antibody response to liposomal Shistosoma mansoni glutathione-S-transferase (Sm28GST) after oral administration, was determined. Antibody responses were compared with alum-adsorbed and N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP)-antigen mixtures. For the s.c. route, dipalmitoylphosphatidylcholine (DPPC)/dimyristoylphosphatidylglycerol (DMPG) liposomes induced 54-60% IgG1 and 35-44% IgG(2a+2b). DPPC/dipalmitoylphosphatidylethanolamine (DPPE) liposomes induced 73-78% IgG1 and 15-25% IgG(2a+2b). DPPC/ phosphatidylserine (PS) liposomes induced 86-89% IgG1 and 8-12% IgG(2a+2b). Alum and MDP induced 79-91% IgG1 and 4-17% IgG(2a+2b). The rank order of adjuvanticity for induction of IgG antibody was DPPC/DMPGDPPC/PE > > alum > > MDPDPPC/PS for all three antigens. DPPC/DMPG liposomes were the only effective adjuvant for the induction of secretory IgA and circulatory IgE and IgG antibodies against Sm28GST after oral administration. The failure of liposome-antigen mixtures to elicit an antibody response showed that liposomal incorporation of the antigens was obligatory for adjuvant activity. These results demonstrate that the correlation between phospholipid composition and adjuvanticity is independent of liposome charge, antigen, or route of administration.

Adjuvants, Immunologic↗

PubMed1994

Construction, expression, and immunogenicity of the Schistosoma mansoni P28 glutathione S-transferase as a genetic fusion to tetanus toxin fragment C in a live Aro attenuated vaccine strain of Salmonella.

A vector has been constructed to allow genetic fusions of guest antigens via a hinge domain to the C terminus of the highly immunogenic C fragment of tetanus toxin. A fusion has been constructed with the gene encoding the protective 28-kDa glutathione S-transferase (EC 2.5.1.18) from Schistosoma mansoni. The recombinant vector has been electroporated into the nonvirulent Salmonella typhimurium aroA live vaccine strain SL3261. The corresponding chimeric protein is stably expressed in a soluble form in Salmonella as evaluated by Western blotting with fragment C and glutathione S-transferase antisera. Mice immunized intravenously with a single dose of the live recombinant bacteria elicit antibodies to both fragment C and glutathione S-transferase as detected by enzyme-linked immunosorbent assays. Furthermore, all of the mice were solidly protected when challenged with lethal doses of either tetanus toxin or the virulent Salmonella typhimurium strain C5. Mice have also elicited antibodies to fragment C and glutathione S-transferase after oral immunization. It may be that a live trivalent vaccine against typhoid, tetanus, and schistosomiasis is feasible.

Animals↗

PubMed1994

Surface-associated filamentous hemagglutinin induces autoagglutination of Bordetella pertussis.

Filamentous hemagglutinin (FHA) is a major adhesin produced by Bordetella pertussis, the etiologic agent of whooping cough. FHA has been shown to be surface associated but is also secreted by virulent bacteria. Microscopic observations of lungs of mice infected with B. pertussis showed that the bacteria grow as clusters within the alveolar lumen. When B. pertussis was cultivated in vitro with chemically defined medium, bacteria grew as aggregates, mimicking growth observed in vivo. This aggregation was abolished by the addition of cyclodextrin (CDX) to the growth medium and depended on the production of FHA, because a mutant lacking the FHA structural gene failed to form aggregates in a CDX-free medium. Western blot (immunoblot) analyses revealed that, in the absence of CDX, FHA was attached to the bacterial surface and was not efficiently released into the growth medium. Hydrophobic chromatography of FHA showed that CDX drastically reduced the hydrophobicity of FHA, suggesting a direct binding of CDX to FHA, which was further supported by the partial protection of FHA from trypsin digestion in the presence of CDX. In addition, free FHA can interact in a CDX-inhibitable manner with solid phase-immobilized FHA. It can therefore be postulated that the B. pertussis aggregates are most likely due to direct FHA-FHA interaction.

Adhesins, Bacterial↗

PubMed1994

Development of a vaccine strategy against human and bovine schistosomiasis. Background and update.

Two specific characteristics of schistosome infection are of primordial importance to the development of a vaccine: schistosomes do not multiply within the tissues of their definitive hosts (unlike protozoan parasites) and a partial non-sterilizing immunity can have a marked effect on the incidence of pathology and on disease transmission. Since viable eggs are the cause of disease pathology, a reduction in worm fecundity whether or not accompanied by a reduction in parasite burden is a sufficient goal for vaccine induced immunity. We originally showed that IgE antibodies played in experimental models a pivotal role for the development of protective immunity. These laboratory findings have now been confirmed in human populations. Following the molecular cloning and expression of a 28 kDa protein of Schistosoma mansoni and its identification as a glutathione-S-transferase, immunization experiments have been undertaken in several animal species (rats, mice, baboons). Together with a significant reduction in parasite burden, vaccination with Sm28 GST was recently shown to reduce significantly parasite fecundity and egg viability leading to a decrease in liver pathology. Whereas IgE antibodies were shown to be correlated with protection against infection, IgA antibodies have been identified as one of the factors affecting egg laying and viability. In human populations, a close association was found between IgA antibody production to Sm28 GST and the decrease of egg output. The use of appropriate monoclonal antibody probes made it possible to demonstrate that the inhibition of parasite fecundity following immunization was related to the inhibition of enzymatic activity of the molecule.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Production and enhanced anti-tumor activity of tumor necrosis factor in mice treated with cyclophosphamide.

We demonstrated recently that the production of tumor necrosis factor (TNF) is induced in normal mice and in the immunosuppressed nude mouse model by the administration of muramyl dipeptide (MDP) derivatives followed by endotoxin (lipopolysaccharide). In the present study, the ability of this treatment to induce the production of TNF in mice receiving cyclophosphamide (CY) was examined. Two days following treatment with high-dose CY (250 mg/kg), mice exhibited leukocytopenia and drastically reduced splenic weight. However, these animals remained capable of producing TNF, albeit at lower levels, when treated with MDP derivatives and lipopolysaccharide (LPS), particularly when the lipophilic analogue MDP-dipalmitoyl glycerol (GDP) was utilized. TNF was also induced by the administration of MDP-GDP and LPS to Meth A sarcoma-bearing mice treated with this dose of CY. Furthermore, in all animals receiving this combination therapy, sarcoma necrosis and complete regression were obtained without any sign of tumor regrowth. A dose of 100 mg/kg CY was not effective for inhibiting tumor regrowth under the same experimental conditions. These results demonstrated that the anti-tumor activity of endogenously induced TNF is potentiated by combined therapy with a high dose of CY.

Acetylmuramyl-Alanyl-Isoglutamine↗