TB skin test recombinant proteins as vaccine candidates

Abstract

Incomplete protection of BCG vaccines, high variability of tuberculosis strains, together with the growing antibiotic resistance of mycobacterium tuberculosis, actualize the need to develop new anti-tuberculosis vaccines. Several novel experimental candidate vaccines based on recombinant proteins, such as those based on the M. tuberculosis ESAT-6 and CFP-10 antigens, are currently being studied in clinical trials. The genome region coding for ESAT-6 and CFP-10 antigens is deleted in BCG strains, so the BCG-immunized individuals cannot develop an immune response against the recombinant ESAT-6/CFP-10 antigen. Therefore, a positive immune reaction to these antigens in TB tests indicates the tested individual has earlier been exposed to M. tuberculosis. The ESAT-6/CFP-10 fusion recombinant antigen was, thus, selected as an immunogen to be evaluated on its potential to induce protective immunity against tuberculosis in a mice model when combined with a birch bark betulin-based vaccine adjuvant. The effect of use was assessed based on the results of histological evaluation of the infected lung tissue in mice and the Mtb lung content. The results herein reported eventually demonstrated that the use of corpuscular adjuvant-based (betulin) ESAT-6/CFP-10 vaccine preparation can induce the immune response commensurate to that of when immunized with the BCG vaccine.