Immunochemical characterization of saline-extracted antigens of Mycobacterium tuberculosis H37Ra

The saline extract (SE) of Mycobacterium tuberculosis H37Ra yielded four major fractions on Sephadex G-100, with average molecular weights of 48,000 (fraction I, F I) 32,000 (fraction II, F II), 15,000 (fraction III, F III) and 5,000 (fraction IV, F IV). FI and FII gave single bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, showed complete immunological cross-reactivity with each other and were more potent in reacting with antibodies in patients' (tuberculosis) sera than sonicate, SE, purified protein derivative, F III and F IV when tested in a competition enzyme-linked immunosorbent assay.