Lang Bao
Sichuan University, China
Title: The Study on immunogenicity and protective efficacy of recombinant BCG against tuberculosis
Biography
Biography: Lang Bao
Abstract
Introduction: Tuberculosis (TB) is a serious infectious disease caused by M. tuberculosis. BCG had been considered to be the only available and effective vaccine in prevention of TB. However, the protective efficacy of BCG on TB was still controversial in different populations and age. Thus, improved TB vaccines are urgently needed to develop as an alternative to BCG which was able to activate immune response and protect against severe forms of TB effectively. Method: Two BCG strains (Pasteur and Shanghai) were used parental strain and specific antigens of M. tuberculosis Ag85A, CFP10, ESAT-6 and immune regulation cytokines GM-CSF, IL-12p70 were integrated into BCGs respectively. BALB/c female mice were immunized subcutaneously with single-gene rBCGs and multiple-gene rBCGs. The specific antibody levels of lgG, lgG1 and lgG2a in immunized mice were detected by ELISA assay. Detection of proliferation of splenic lymphocytes and splenocytes subsets by flow cytometry were conducted. Nine rBCG strains were chosen for protective efficacy test. After eight weeks of immunization with rBCGs, mice were challenged intravenously by M. tuberculosis H37Rv. Histopathological examination and bacterial load was performed on the lung, spleen tissues of immune mice. Results: Both single-gene rBCGs and multiple-gene rBCGs could induce strong humoral and Th1 cellular immune reaction. Significantly higher levels of Th1 cytokines IFN-γ was revealed in both multiple and singlegene rBCGs, while Th2 cytokines IL-4 was not detected in all rBCGs. After 18 weeks, the survival rate was 100% in rBCG- Pasteur: A, rBCG- Pasteur: AE and 80% in rBCG-SHanghai: IE, rBCG-Pasteur: GC only 60% in rBCG- Pasteur: GCE. Conclusion: rBCG had excellent immunogenicity and immune protective efficacy. It could regulate the level of TNF- alpha by p38 MAPK and NF-kB signaling pathway and induce the apoptosis of macrophages. BCGPasteur is more suitable for parental BCG than the BCG-SHanghai. These findings can provide ideas and experimental basis for the development of anti-tuberculosis recombinant vaccines.