Effect of sigH-rshA overexpression on the pathogencity of BCG strains

Abstract:

Mycobacterium bovis Bacille Calmette-Guérin (BCG) is the only licensed vaccine for prevention of tuberculosis, whereas the genomic changes lead to differences in the protective effect and safety among strains.[Objective] To study the correlation between sigH-rshA overexpression and pathogenicity of BCG strains in DU2 groups Ⅲ and Ⅳ.[Methods] The recombinant BCG China and BCG Japan strains overexpressing sigH-rshA were established by molecular cloning, and the gene expression was verified by RT-PCR and Western blotting. We used macrophages of mouse origin and server combined immune-deficiency (SCID) mouse infection model to assess the pathogenicity of the recombinant BCG. We employed enzyme-linked immunosorbent assay (ELISA) to assess the secretion of tumor necrosis factor-α (TNF-α).[Results] The overexpression of SigH-RshA protein significantly promoted the intracellular proliferation of BCG and stimulated macrophages to produce more TNF-α. The results of the experiment with SCID mice showed that overexpression of sigH-rshA increased the virulence of recombinant BCG strains to immunodeficient mice.[Conclusion] The overexpression of sigH-rshA can enhance the pathogenicity of BCG strains to macrophages and mice.