RESUMO
Tuberculosis (TB) remains to be an enormous global health problem. The inconsistent protection efficacy of Bacille Calmette-Guérin (BCG) calls for new vaccines for TB. One choice to improve the efficacy of BCG vaccine is recombinant BCG (rBCG). Experimental evidences have revealed that Ag85B, ESAT-6 and Rv3620c are important immunodominant antigens of Mycobacterium tuberculosis. In this study, we have constructed a novel rBCG expressing fusion protein Ag85B-ESAT6-Rv3620c and evaluated the immunogenicity of this rBCG in C57BL/6 mice. Results show that there is a strong TB-specific CD4(+) and CD8(+) T lymphocytes proliferation in mice immunized with this rBCG vaccine. A single dose immunization of rBCG could induce a significantly strong Th1 immune response characterized by an increasing ratio of antigen-specific IgG2b/IgG1 as well as a high expression level of Th1 cytokines such as IFN-γ, TNF-α and IL-2. This conclusion was confirmed by a decreased secretion of Th2 cytokine IL-10. Moreover, this rBCG induced a strong humoral response in mice with an increasing antigen-specific IgG titer. Therefore, we concluded that this rBCG could significantly increase both Th1 type cellular immune response and antigen-specific humoral response compared with BCG. The above observations demonstrated that rBCG::Ag85B-ESAT6-Rv3620c is a potential candidate vaccine against M. tuberculosis for further study.
Assuntos
Aciltransferases/imunologia , Antígenos de Bactérias/imunologia , Vacina BCG/imunologia , Proteínas de Bactérias/imunologia , Mycobacterium bovis/genética , Células Th1/imunologia , Aciltransferases/biossíntese , Aciltransferases/genética , Animais , Anticorpos Antibacterianos/sangue , Antígenos de Bactérias/biossíntese , Antígenos de Bactérias/genética , Vacina BCG/administração & dosagem , Vacina BCG/genética , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/genética , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Proliferação de Células , Citocinas/metabolismo , Imunoglobulina G/sangue , Camundongos Endogâmicos C57BL , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/imunologia , Vacinas Sintéticas/administração & dosagem , Vacinas Sintéticas/genética , Vacinas Sintéticas/imunologiaRESUMO
Dendritic cells (DCs) are important for the initiation of the adaptive immune response against Mycobacterium tuberculosis. Autophagy is an innate and adaptive defense mechanism and important for the control of M. tuberculosis. However, the role of autophagy in the adaptive immune response against M. tuberculosis remains to be determined. In the present study, we studied the effects of autophagy on the maturation of DCs infected with Bacillus Calmette- Guerin (BCG). The phenotype and function of the DCs were assessed by measuring the expression of CD86 and HLA-DR and the secretion of IL-10 and IL-6. Autophagy was evaluated by the change in LC3II, a molecular marker for autophagy. Following stimulation of autophagy, DCs that were matured in the presence of BCG showed enhanced expression of CD86 and HLA-DR and increased IL-6 production. The expression of LC3II was increased after the stimulation of autophagy. These results demonstrated that autophagy might result in the increased maturation of BCG-infected DCs, suggesting that autophagy could contribute to an enhanced adaptive immune response against M. tuberculosis.