The recombinant fusion protein CFP10-ESAT6-dIFN has protective effect against tuberculosis in guinea pigs

Development of effective vaccine candidates against tuberculosis (TB) is currently the most important challenge in the prevention of this disease since the BCG vaccine fails to guarantee a lifelong protection, while any other approved vaccine with better efficiency is still absent. The protective effect of the recombinant fusion protein CFP10-ESAT6-dIFN produced in a prokaryotic expression system (Escherichia coli) has been assessed in a guinea pig model of acute TB. The tested antigen comprises the Mycobacterium tuberculosis (Mtb) proteins ESAT6 and CFP10 as well as modified human γ-interferon (dIFN) for boosting the immune response. Double intradermal immunization of guinea pigs with the tested fusion protein (2 × 0.5 µg) induces a protective effect against subsequent Mtb infection. The immunized guinea pigs do not develop the symptoms of acute TB and their body weight gain was five times more as compared with the non-immunized infected guinea pigs. The animal group immunized with this dose of antigen displays the minimum morphological changes in the internal organs and insignificant inflammatory lesions in the liver tissue, which complies with a decrease in the bacterial load in the spleen and average Mtb counts in macrophages.