Isolation of Mycobacterium tuberculosis protein antigens ES-3 1, ES-43 and EST-6 of diagnostic interest from tubercle bacilli by affinity chromatography.

Immunodiagnostically useful M. tuberculosis H37Ra protein antigens ES-31, ES-43 and EST-6 were isolated from detergent soluble sonicate (DSS) antigen using monospecific antibodies by affinity chromatography and compared with similar antigens isolated from M. tuberculosis culture filtrate for seroreactivity in tuberculosis sera by Indirect Enzyme Linked Immunosorbent Assay. Recovery of affinity purified ES-31, ES-43 and EST-6 antigen from DSS antigen was approximately 3, 3.5 and 4% respectively, compared to 10, 9 and 6.3% from culture filtrate. Affinity purified ES-31, ES-43 and EST-6 antigens from both culture filtrate as well as DSS antigen showed similar seroreactivity with overall sensitivity 85, 80 and 75% respectively and specificity of 85% at optimum concentration of 50 pg protein of each antigen. The results suggest that DSS antigen may be a promising antigen source for isolating antigens of diagnostic interest obviating the need for cumbersome, time-consuming culture techniques of mycobacteria.