The Schistosoma mansoni cyclophilin A epitope 107-121 induces a protective immune response against schistosomiasis

Great efforts have been made to identify promising antigens and vaccine formulations against schistosomiasis. Among the previously described Schistosoma vaccine candidates, cyclophilins comprise an interesting antigen that could be used for vaccine formulations. Cyclophilin A is the target for the cyclosporine A, a drug with schistosomicide activity, and its orthologue from Schistosoma japonicum induces a protective immune response in mice. Although Schistosoma mansoni cyclophilin A also represents a promising target for anti-schistosome vaccines, its potential to induce protection has not been evaluated. In this study, we characterized the cyclophilin A (SmCyp), initially described as Smp17.7, analyzed its allergenic potential using in vitro functional assays, and evaluated its ability to induce protection in mice when administered as an antigen using different vaccine formulations and strategies. Results indicated that SmCyp could be successfully expressed by mammalian cells and bacteria. The recombinant protein did not promote IgE-reporter system activation in vitro, demonstrating its probable safety for use in vaccine formulations. T and B-cell epitopes were predicted in the SmCyp sequence, with two of them located within the active isomerase site. The most immunogenic antigen, SmCyp (107–121), was then used for immunization protocols. Immunization with the SmCyp gene or protein failed to reduce parasite burden but induced an immune response that modulated the granuloma area. In contrast, immunization with the synthetic peptide SmCyp (107–121) significantly reduced worm burden (48–50%) in comparison to control group, but did not regulate liver pathology. Moreover, the protection observed in mice immunized with the synthetic peptide was associated with the significant production of antibodies against the SmCyp (107–121) epitope. Therefore, in this study, we identified an epitope within the SmCyp sequence that induces a protective immune response against the parasite, thus representing a promising antigen that could be used for vaccine formulation against schistosomiasis

Carbohydrate-mediated antigenic cross-reactivity between Schistosoma mansoni antigens and environmental allergens

There has been an increase in allergic diseases such as asthma, which triggers an IgE allergic reaction, in countries with advanced health systems. However, in helminth-endemic countries, an inverse correlation between infection with parasitic helminths including schistosomes and allergic sensitisation has been observed. This has led authors to formulate the so-called hygiene hypothesis. Previous studies have shown that rabbit IgG antibodies against Schistosoma mansoni soluble egg antigens (SmSEA) cross-reacted with various allergens such as peanut, rubber latex and grass and tree pollens. Here we describe antigenic molecules that cross-react with rabbit anti-S. mansoni IgG antibodies in extracts of the Australian cockroach (ACR) Periplaneta australasiae and the house dust mite (HDM) Dermatophagoides farinae. Our investigation was carried out using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and western immunoblotting using rabbit antisera raised against S. mansoni antigen. The purified material was subjected to Tandem mass spectrometry to identify S. mansoni antigen that is cross-reactive with molecules in an extract of the different allergens. We found the cross-reactive allergens as Der f 15 in HDM and two homologues of the Periplaneta americana cockroach allergen Cr-PI/Per a 3 in ACR. Acid elution of anti-SmSEA antibodies cross-reactive with the allergens reacted with the major egg antigens of S. mansoni namely IPSE-alpha 1, Kappa-5 and Omega-1. Moreover, rabbit anti-schistosome IgG antibodies eluted from HDM reacted with a variety of plant extracts. Treatment with sodium meta periodate ablated most of the cross-reactivity of the antigen suggesting that it might be due to cross-reactive carbohydrate determinants (CCDs). In this work, we have also used the humanized Rat Basophilic Leukemia RS-ATL8 reporter system which is used to detect allergen-specific IgE in human serum. The reason for using such a system was to investigate whether anti-schistosome IgG antibodies that are cross-reactive with an allergen – D. farinae - can act as ‘blocking antibodies. We found that the two different donor serum samples used were able to sensitise the reporter cells upon challenge with anti-human IgE, but when challenged with the mite allergen there was only a very low response. This could mean that the molecule Der f 15, which is a minor HDM allergen, might not be the target of an allergen-specific IgE response in these two donors. Furthermore, we developed an in vitro system to study if recombinant IgG can block IgE mediated activation using Phl p 7 a well-known characterised allergen. This was carried out by expressing IgE and IgG protein in mammalian HEK 293 cells, the expressed IgG protein was purified using Affinity Chromatography ÄKTAstart system. Our data show that the two proteins were successfully expressed, and the IgG protein was also purified successfully. In conclusion, chapter 3 and 4 findings could provide a useful application for improved allergen-specific immunotherapy. Furthermore, we could use our reporter system to demonstrate that recombinant IgG antibodies can block the interaction of anti-Phl p 7 IgE antibody with Phl p 7 allergen, thereby blocking allergen-mediated crosslinking of IgE receptors in chapter 5

Carbohydrate-mediated antigenic cross-reactivity between Schistosoma mansoni antigens and environmental allergens

There has been an increase in allergic diseases such as asthma, which triggers an IgE allergic reaction, in countries with advanced health systems. However, in helminth-endemic countries, an inverse correlation between infection with parasitic helminths including schistosomes and allergic sensitisation has been observed. This has led authors to formulate the so-called hygiene hypothesis. Previous studies have shown that rabbit IgG antibodies against Schistosoma mansoni soluble egg antigens (SmSEA) cross-reacted with various allergens such as peanut, rubber latex and grass and tree pollens. Here we describe antigenic molecules that cross-react with rabbit anti-S. mansoni IgG antibodies in extracts of the Australian cockroach (ACR) Periplaneta australasiae and the house dust mite (HDM) Dermatophagoides farinae. Our investigation was carried out using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and western immunoblotting using rabbit antisera raised against S. mansoni antigen. The purified material was subjected to Tandem mass spectrometry to identify S. mansoni antigen that is cross-reactive with molecules in an extract of the different allergens. We found the cross-reactive allergens as Der f 15 in HDM and two homologues of the Periplaneta americana cockroach allergen Cr-PI/Per a 3 in ACR. Acid elution of anti-SmSEA antibodies cross-reactive with the allergens reacted with the major egg antigens of S. mansoni namely IPSE-alpha 1, Kappa-5 and Omega-1. Moreover, rabbit anti-schistosome IgG antibodies eluted from HDM reacted with a variety of plant extracts. Treatment with sodium meta periodate ablated most of the cross-reactivity of the antigen suggesting that it might be due to cross-reactive carbohydrate determinants (CCDs). In this work, we have also used the humanized Rat Basophilic Leukemia RS-ATL8 reporter system which is used to detect allergen-specific IgE in human serum. The reason for using such a system was to investigate whether anti-schistosome IgG antibodies that are cross-reactive with an allergen – D. farinae - can act as ‘blocking antibodies. We found that the two different donor serum samples used were able to sensitise the reporter cells upon challenge with anti-human IgE, but when challenged with the mite allergen there was only a very low response. This could mean that the molecule Der f 15, which is a minor HDM allergen, might not be the target of an allergen-specific IgE response in these two donors. Furthermore, we developed an in vitro system to study if recombinant IgG can block IgE mediated activation using Phl p 7 a well-known characterised allergen. This was carried out by expressing IgE and IgG protein in mammalian HEK 293 cells, the expressed IgG protein was purified using Affinity Chromatography ÄKTAstart system. Our data show that the two proteins were successfully expressed, and the IgG protein was also purified successfully. In conclusion, chapter 3 and 4 findings could provide a useful application for improved allergen-specific immunotherapy. Furthermore, we could use our reporter system to demonstrate that recombinant IgG antibodies can block the interaction of anti-Phl p 7 IgE antibody with Phl p 7 allergen, thereby blocking allergen-mediated crosslinking of IgE receptors in chapter 5