A DNA vaccine expressing CFP21 and MPT64 fusion protein enhances BCG-induced protective immunity against Mycobacterium tuberculosis infection in mice

Abstract

The efficacy of Bacillus Calmette-Guérin (BCG) vaccine in preventing adult tuberculosis (TB) is highly variable. Genetic differences between BCG vaccine substrains, which can be divided into early strains and late strains based on the loss of region of difference two (RD2), may result in the variability and BCG substrains. The effect of lack of RD2 on the protective efficacy of BCG substrains against TB remains unknown. In this study, we demonstrated that CFP21 and MPT64(rCM) fusion protein, encoded by RD2 of Mycobacterium tuberculosis, could stimulate higher level of interferon (IFN)-γ in tuberculin skin test (TST)-positive healthy population than in TST-negative healthy population. Compared with naive mice challenged with virulent M. tuberculosis H37Rv, C57BL/6 mice vaccinated with pcD2164 DNA expressing rCM protein resulted in a greater decrease in the bacterial load of lung. Moreover, pcD2164 could boost the protective immunity in mice primed by BCG than BCG alone or DNA vaccination alone, as evidenced by lower bacterial load in the lung tissue and reduced lung pathology. The protection induced by BCG prime-DNA vaccine boost strategy was associated with significant increases in rCM protein-specific IFN-γ. Therefore, our results clearly indicate that the loss of RD2 has an important influence on the protective efficacy of different BCG substrains. These findings will benefit the optimal choice of BCG substrain for neonatal immunization and rational design of new vaccines for the prevention of TB.

Differential Immune Responses and Protective Effects in Avirulent Mycobacterial Strains Vaccinated BALB/c Mice

“…The detail procedures were performed as previously described [35]. Tested cDNAs were normalized to the endogenous RNA levels of GAPDH.…”

The <italic>Mycobacterium bovis</italic> BCG prime-Rv0577 DNA boost vaccination induces a durable Th1 immune response in mice

“…These studies revealed that BCG prime-boost approach could activate T cell to evoke strong immune responses including both CD4+ T cell and CD8+ T cell immune responses [10]. We thus focused on the prime-boost strategy that combines BCG with a subsequent booster vaccine candidate.…”

A Novel Tuberculosis DNA Vaccine in an HIV-1 p24 Protein Backbone Confers Protection against Mycobacterium tuberculosis and Simultaneously Elicits Robust Humoral and Cellular Responses to HIV-1

“…Studies show that Ag85A and Ag85B stimulate strong humoral and cell-mediated immune responses and produce significant protection against Mycobacterium tuberculosis H37Rv challenge (18,20,22,38). In addition, MPT64, a member of the culture filtrate protein (CFP) family, can induce a strong T cell response (42). TB10.4, a member of a subfamily of the ESAT6 family, is even more vigorously recognized than ESAT-6 (6-kDa early secreted antigen target of M. tuberculosis) in TB patients (35).…”