Improved cellular immune response elicited by a ubiquitin-fused DNA vaccine against Mycobacterium tuberculosis

This study evaluated the immune response elicited by a ubiquitin (Ub)-fused MPT64 DNA vaccine against Mycobacterium tuberculosis. BALB/c mice were vaccinated with plasmid DNA encoding MPT64 protein, Ub-fused MPT64 DNA vaccine (UbGR-MPT64), and negative DNA vaccines, respectively. MPT64 DNA vaccine immunization induced a Thl-polarized immune response. The production of Thl-type cytokine (interferon-gamma [IFN-γ]) and proliferative T cell responses were enhanced significantly in mice immunized with UbGR-MPT64 fusion DNA vaccine, compared with nonfusion DNA vaccine. Moreover, this fusion DNA vaccine also resulted in an increased relative ratio of IgG2a to IgGl and the cytotoxicity of T cells. IFN-γ intracellular staining of splenocytes indicated that UbGR-mpt64 fusion DNA vaccine activated CD4+ and CD8+ T cells, particularly CD8+ T cells. Thus, this study demonstrated that the UbGR-MPT64 fusion DNA vaccine inoculation could improve antigen-specific cellular immune responses, which is helpful for protection against TB.