Biotechnology in the development of new vaccines and diagnostic reagents against tuberculosis

Tuberculosis (TB) is a disease of global concern. About one third of the world population is infected with Mycobacterium tuberculosis. Every year, approximately 8 million people get the disease and 2 million die of TB. The currently available vaccine against TB is the attenuated strain of Mycobacterium bovis, Bacillus Calmette Guerin (BCG), which has failed to provide consistent protection in different parts of the world. The commonly used diagnostic reagent for TB is the purified protein derivative (PPD) of M. tuberculosis, which is nonspecific because of the presence of antigens crossreactive with BCG and environmental mycobacteria. Thus there is a need to identify M. tuberculosis antigens as candidates for new protective vaccines and specific diagnostic reagents against TB. By using the techniques of recombinant DNA, synthetic peptides, antigen-specific antibodies and T cells etc., several major antigens of M. tuberculosis have been identified, e.g. heat shock protein (hsp)60, hsp70, Ag85, ESAT-6 and CFP10 etc. These antigens have shown promise as new candidate vaccines and/or diagnostic reagents against TB. In addition, recent comparisons of the genome sequence of M. tuberculosis with BCG and other mycobacteria have unraveled M. tuberculosis specific regions and genes. Expression and immunological evaluation of these regions and genes can potentially identify most of the antigens of M. tuberculosis important for developing new vaccines and specific diagnostic reagents against TB. Moreover, advances in identification of proper adjuvant and delivery systems can potentially overcome the problem of poor immunogenicity/short-lived immunity associated with protein and peptide based vaccines. In conclusion, the advances in biotechnology are contributing significantly in the process of developing new protective vaccines and diagnostic reagents against TB.