[LC3-LpqH enhances the immunoprotection of Ag85B DNA vaccine against Mycobacterium tuberculosis].

Objective: To explore the effect of microtubule-associated protein light chain 3- lipoprotein antigen precursor (pCMV-LC3-LpqH) as an DNA adjuvant on the immunoprotection of the anti-tuberculosis DNA vaccine encoding Ag85B antigen from Mycobacterium tuberculosis (MTB).
Methods: BALB/c mice were randomly divided into four groups that were immunized three times with pCMV-Ag85B, pCMV-LpqH/pCMV-Ag85B, pCMV-LC3-LpqH/pCMV-Ag85B and pCMV, respectively. Two weeks after the final vaccination, the titers and subtypes of anti-Ag85B IgG of BALB/c mice were detected by ELISA. In vitro, the levels of interleukin 2 (IL-2), interferon γ (IFN-γ), IL-4 and IL-10 that were secreted from Ag85B-stimulated splenocytes were also measured by ELISA. Three months after the final vaccination, mice were challenged with virulent MTB H37Rv strain through the tail veins. The mice spleens and lungs were dissected out for counting colony-forming unit (CFU) and observing pulmonary histopathological changes after MTB infection.
Results: LC3-LpqH/Ag85B-immunized mice showed the significant increase of IgG2a, IL-2 and IFN-γ, along with the decrease of IgG1, IL-4 and IL-10, lower MTB CFU in the spleens and lungs and a marked relief in pulmonary injury.
Conclusion: LC3-LpqH could enhance Ag85B-specific Th1 immune response that exerts a superior immune protection, which might be a new practical strategy for developing MTB vaccines.