PROTEOMIC CONTIGS OF MYCOBACTERIUM-TUBERCULOSIS AND MYCOBACTERIUM-BOVIS (BCG) USING NOVEL IMMOBILIZED PH GRADIENTS

Tuberculosis remains a major health problem throughout the world and t he failure of the existing bacille Calmette-Guerin (BCG) vaccine in re cent trials has prompted a search for potential replacements. Recent a dvances in molecular and cell biology have cast doubts on the ability of genetic analysis alone to predict polygenic human diseases and othe r complex phenotypes and have therefore redirected our attention to pr oteome studies to complement information obtained from DNA sequencing initiatives. Novel acidic (pH 2.3-5) and basic (pH 6-11) IPG gel gradi ents were employed in conjunction with commercially available pH 4-7 g radients to significantly increase (fourfold) the number of protein sp ots previously resolved on two-dimensional (2-D) gels of Mycobacterium species. A total of 772 and 638 protein spots were observed for M. bo vis BCG and M. tuberculosis H37Rv, respectively, the latter correspond ing to only the pH regions 4-7 and 6-11. Of interest was the bimodal d istribution observed for proteins separated from M. bovis BCG across b oth M-r and pH ranges. Some differences in protein expression were obs erved between these two organisms, contrary to what may have been expe cted considering the high degree of conservation in gene order and seq uence similarity between homologous genes. Further work will be direct ed towards a more detailed analysis of these differences, so as to all ow more accurate diagnosis between vaccination and active tuberculosis . The latter is of major importance to epidemiological studies and for patient management.