Nanostructured SBA-15 silica: An effective protective vehicle to oral hepatitis B vaccine immunization.

Due to its physicochemical properties, nanostructured mesoporous SBA-15 silica shows great potential as a vaccine adjuvant. This study evaluated the capacity of SBA-15 to encapsulate/adsorb the recombinant purified HBsAg from the Hepatitis B virus and the immunoresponsiveness of mice orally immunized with HBsAg inside SBA-15. A simulation of small angle X-ray scattering experimental results, together with the nitrogen adsorption isotherms data, allowed to determine the appropriate mass ratio of HBsAg:SBA-15, indicating antigen encapsulation into SBA-15 macroporosity. This was also evaluated by bicinchoninic acid assay and gel electrophoresis. The recruitment of inflammatory cells, an increase in production of specific antibodies, and the non-influence of silica on TH1 or TH2 polarization were observed after oral immunization. Besides, SBA-15 enhanced the phagocytosis of ovalbumin by dendritic cells, an important key to prove how this adjuvant works. Thus, it seems clear that the nanostructured SBA-15 is an effective and safe adjuvant for oral immunizations.

Generation of recombinant bacillus Calmette-Guérin and Mycobacterium smegmatis expressing BfpA and intimin as vaccine vectors against enteropathogenic Escherichia coli.

Enteropathogenic Escherichia coli (EPEC) is an important cause of diarrhea in children. EPEC adheres to the intestinal epithelium and causes attaching and effacing (A/E) lesions. Recombinant Mycobacterium smegmatis (Smeg) and Mycobacterium bovis BCG strains were constructed to express either BfpA or intimin. The entire bfpA gene and a portion of the intimin gene were amplified by PCR from EPEC genomic DNA and inserted into the pMIP12 vector at the BamHI/KpnI sites. The pMIP_bfpA and pMIP_intimin vectors were introduced separately into Smeg and BCG. Recombinant clones were selected based on kanamycin resistance and designated rSmeg_pMIP_(bfpA or intimin) and rBCG_pMIP_(bfpA or intimin). The expression of bfpA and intimin was detected by Immunoblotting using polyclonal anti-BfpA and anti-intimin antibodies. The immunogenicity of these proteins was assessed in C57BL/6 mice by assaying the feces and serum for the presence of anti-BfpA and anti-intimin IgA and IgG antibodies. TNF-α and INF-γ were produced in vitro by spleen cells from mice immunized with recombinant BfpA, whereas TNF-γ was produced in mice immunized with recombinant intimin. The adhesion of EPEC (E2348/69) to HEp-2 target cells was blocked by IgA or IgG antibodies from mice immunized with recombinant BfpA or intimin but not by antibodies from non-immunized mice. Immunogenic non-infectious vectors containing relevant EPEC virulence genes may be promising vaccine candidates.

Utilização da sílica nanoestruturada SBA-15 como adjuvante em imunizações com a vacina para hepatite B / Nanostructured SBA-15 silica as an adjuvant in immunizations with hepatitis B vaccine

Objective: To evaluate the applicability of SBA-15 silica as an adjuvant in immunizations with purified particles of the viral protein HBsAg, the main component of hepatitis B vaccine, Butang®, produced by Instituto Butantan. Methods: BALB/c mice orally or subcutaneously received 0.5 mug of HBsAg adsorbed/encapsulated to SBA-15 or adsorbed to Al(OH)3. To assess the secondary immune response, a subcutaneous booster was administered 30 days after the first immunization. Individual serum and fecal samples of each group were periodically collected for specific antibody titration by ELISA. Results: Analysis of secretory IgA showed that mice orally primed with HBsAg on SBA-15 had increased levels of specific antibodies in primary and secondary immune responses. Specific serum IgA and IgG titers in HBsAg:SBA-15-orally immunized mice reached higher levels after the booster, demonstrating the effectiveness of oral vaccination with the use of silica. All immunized groups showed higher IgG1 levels. Conclusion: Our results clearly indicate the promising use of SBA-15 as an adjuvant, especially in oral immunizations.

Objetivo: Demonstrar a aplicabilidade da sílica do tipo SBA-15 como adjuvante nas imunizações com a proteína recombinante HBsAg do vírus da hepatite B, principal componente da vacina Butang® produzida pelo Instituto Butantan. Métodos: Camundongos BALB/c receberam, pela via oral ou subcutânea, 0,5 mig do HbsAg adsorvido/encapsulado à SBA-15 ou adsorvido ao Al(OH)3. Para avaliar a resposta imune secundária, uma dose de reforço foi administrada subcutaneamente 30 dias após a primeira imunização. Amostras individuais de soro e fezes foram coletadas periodicamente para titulação de anticorpos específicos por ELISA. Resultados: A análise de IgA secretada mostrou que camundongos imunizados pela via oral com HbsAg em SBA-15 apresentaram aumento nos níveis de anticorpos específicos nas respostas primária e secundária. Ainda, após o reforço, observaram-se maiores níveis de IgA e IgG séricas anti-HBsAg no grupo preparado com HBsAg:SBA-15 pela via oral. Todos os grupos imunizados apresentaram maior produção de IgG1. Conclusão: Os resultados indicam o uso promissor da sílica SBA-15 como adjuvante, especialmente nas imunizações pela via oral.

Nanostructured SBA-15 silica as an adjuvant in immunizations with hepatitis B vaccine.

OBJECTIVE: To evaluate the applicability of SBA-15 silica as an adjuvant in immunizations with purified particles of the viral protein HBsAg, the main component of hepatitis B vaccine, Butang®, produced by Instituto Butantan. METHODS: BALB/c mice orally or subcutaneously received 0.5 µg of HBsAg adsorbed/encapsulated to SBA-15 or adsorbed to Al(OH)3. To assess the secondary immune response, a subcutaneous booster was administered 30 days after the first immunization. Individual serum and fecal samples of each group were periodically collected for specific antibody titration by ELISA. RESULTS: Analysis of secretory IgA showed that mice orally primed with HBsAg on SBA-15 had increased levels of specific antibodies in primary and secondary immune responses. Specific serum IgA and IgG titers in HBsAg:SBA-15-orally immunized mice reached higher levels after the booster, demonstrating the effectiveness of oral vaccination with the use of silica. All immunized groups showed higher IgG1 levels. CONCLUSION: Our results clearly indicate the promising use of SBA-15 as an adjuvant, especially in oral immunizations.

Immunological parameters related to the adjuvant effect of the ordered mesoporous silica SBA-15.

In 2006, the first report of a nanostructured material as adjuvant was described establishing the effectiveness of the ordered mesoporous SBA-15 silica as an immune adjuvant. The present study evaluated the SBA-15 capacity to modulate the immune responsiveness of High and Low responder mice immunized with BSA encapsulated/adsorbed in SBA-15 by the intramuscular or oral route and the adjuvant effect was compared with the responsiveness induced by BSA in aluminum hydroxide salts or emulsified in Incomplete Freund adjuvant. These results demonstrate the ability of the non-toxic SBA-15 nanoparticles to increase the immunogenicity and repair the responsiveness of the constitutively low responder individuals inducing both the IgG2a and the IgG1 isotypes, independently of the immune cell committed and conditioning the low phenotype. This new adjuvant may reveal novel therapeutic targets for immune modulation and vaccine design.