ABSTRACT
Tuberculosis (TB) remains an enormous health burden worldwide.To date,Mycobacterium bovis Bacillus Calmette Guerin (BCG) is the unique anti-TB vaccine available for humans,which provides an important but limited protection from the Mycobacterium tuberculosis (Mtb) infection.It is therefore an urgent need to develop better vaccines and vaccination strategies to prevent the spread of Mtb infection.Heterologous prime-boost vaccination strategies using both BCG and novel anti-TB vaccines have been demonstrated to induce robust immune responses than BCG alone.We have previously demonstrated that a recombinant adenoviral vector Ad5-CEAB co-expressing CFP10,ESAT6,Ag85A and Ag85B of Mtb was able to induce robust antigen-specific immune responses in mice.In the present study,we examined immunological effects of Ad5-CEAB in the mice primed with BCG and boosted with a single dose of the virus via an intranasal route.Results demonstrated that this vaccination strategy could effectively induce strong antigen-specific mucosal and humoral immune responses.These immune responses were characterized with an increased productions of cytokines (IL-12 and IFN-γ),increased concentration of secretary IgA (sIgA) in bronchoalveolar lavage fluid (BALF) and serum IgG in mice in comparison with mice in BCG group.These data suggested that the regimen of BCG prime-single dose of Ad5-CEAB boosted strategy was novel for inducing antigen-specific immune responses in response to Mtb antigens in vivo,which warrants for further development of adenoviral-based vaccine against Mtb infection.
ABSTRACT
CFP10, ESAT6, Antigen 85A (Ag85A) and antigen 85B (Ag85B) are the key immunodominant antigens of Mycobacterium tuberculosis. In order to construct a eukaryotic vector able to co-express the four genes in one vector, we amplified the target gene fragments encoding the CFP10, ESAT6, Ag85A and Ag85B antigens and inserted them into the multicloning site of the shuttle plasmid vector pcDNA3.1 (+), of which the CFP10 and ESAT6 encoding genes were in frame fused with a linker encoding (Gly4Ser)3 residue, before the fused gene was inserted downstream of CMV promoter with a bovine growth hormone poly A(BGH pA) sequence at the 3'-end; Ag85A and Ag85B encoding genes were fused with a separation of internal ribosome entry site (IRES) sequence before the fused gene cassette was inserted downstream of RSV promoter with a BGH pA sequence at the 3'-end. The final plasmid containing all four genes was confirmed by sequence analysis and designated as pcDNA-CFP10-ESAT6-Ag85A-Ag85B (pcDNA-CEAB). In order to verify the ability of this construct to express target proteins, we then transfected the recombinant plasmid into Human embryonic kidney (HEK) 293T cells and harvested the cell lysates, and the cell lysates were then separated by SDS-PAGE and subjected to Western blot analysis 48 h after transfection. All four of the target proteins were detected in the cell lysates against the respective specific antibodies, suggesting that we have successfully constructed a eukaryotic vector co-expressing the four immunodominant antigens of Mycobacterium tuberculosis, which lay a foundation for the further study of the immunogenicity and protective activity of the four antigens.