pcDNA3.1- <i>rpfB</i> or pcDNA3.1- <i>rpfD</i> recombinant DNA prevents <i>Mycobacterium tuberculosis</i> infection in BALB/c mice

Tuberculosis (TB) is caused by an infection with <i>Mycobacterium tuberculosis</i>. The Bacille Calmette-Guérin (BCG) vaccine is used to treat TB. However, its efficacy varies in different countries. A new TB vaccine is urgently required to inhibit the spread of TB infection. DNA vaccines are promising for providing an immune response against the disease. The resuscitation-promoting factors B and D (<i>rpfB</i>/<i>rpfD</i>) genes are promising vaccine candidates. In this study, the vaccine candidates pcDNA3.1-<i>rpfB</i> and pcDNA3.1-<i>rpfD</i> were evaluated for their ability to inhibit <i>M. tuberculosis</i> infection in BALB/c mice. Epitope analysis indicates that the recombinant protein sequences of RpfB and RpfD used in this study possess epitopes recognized by T and B lymphocytes. Although the presence of <i>M. tuberculosis</i> cells in lung tissue was not detected, histopathological analysis revealed the absence of lymphoid aggregates in mice vaccinated with pcDNA3.1-<i>rpfB</i> or pcDNA3.1-<i>rpfD</i>, in contrast to those administered with phosphate-buffered saline or pcDNA3.1. In addition, analysis of the humoral immune response showed the highest IgG2a antibody titer in mice immunized with both vaccine candidates. These results support our previous findings, which indicate that pcDNA3.1-<i>rpfB</i> and pcDNA3.1-<i>rpfD</i> have considerable potential as TB vaccine candidates.