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A live attenuated BCG vaccine overexpressing multistage antigens Ag85B and HspX provides superior protection against Mycobacterium tuberculosis infection.

Yuan, Xuefeng; Teng, Xindong; Jing, Yukai; Ma, Jilei; Tian, Maopeng; Yu, Qi; Zhou, Lei; Wang, Ruibo; Wang, Weihua; Li, Li; Fan, Xionglin.
Appl Microbiol Biotechnol; 99(24): 10587-95, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26363555
Tuberculosis (TB) remains one of the most menacing infectious diseases, although attenuated Mycobacterium bovis Bacillus Calmette-Guerin (BCG) vaccine has been widely used to protect children against primary TB. There are increasing evidences that rapid growing and dormant Mycobacterium tuberculosis (M. tuberculosis) coexist in vivo after infection. However, BCG vaccine only elicits cell-mediated immune responses to secretory antigens expressed by rapid growing pathogen. BCG vaccine is thus unable to thwart the reactivation of latent tuberculosis infection (LTBI), and its protection wanes over age after neonatal immunization. In order to extend its ability for a durable protection, a novel recombinant BCG (rBCG) strain, named rBCGXB, was constructed by overexpressing immunodominant multistage antigens of Ag85B and HspX, which are expressed by both rapid replicating and dormant M. tuberculosis. Long-term protective effect and immunogenicity of rBCGXB were compared with the parental BCG in vaccinated C57BL/6 mice. Our results demonstrated that rBCGXB provided the stronger and long-lasting protection against M. tuberculosis H37Rv intranasal infection than BCG. The rBCGXB not only elicited the more durable multistage antigen-specific CD4(+)Th1-biased immune responses and specific polyfunctional CD4(+)T cells but also augmented the CD8(+) CTL effects against Ag85B in vivo. In particular, higher levels of CD4(+) TEM and CD8(+) TCM cells, dominated by IL2(+) CD4(+) and CD8(+) TCM cells, were obtained in the spleen of rBCGXB vaccinated mice. Therefore, our findings indicate that rBCGXB is a promising candidate to improve the efficacy of BCG.
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