Electrophoresis and immunoblotting analysis of the 22-kDa protein. (A) Purification by glutathione affinity chromatography of the 22-kDa protein fused to GST. Eluates were analyzed by SDS-PAGE (15% gel) and stained with Coomassie blue. Lane 1, molecular weight markers; lane 2, purified fusion protein; lane 3, fusion protein cleaved by factor Xa. (B) Immunoblotting analysis with MAbs 9E5 (lane 1), VD12-1 (lane 2), and VIIIH-1 (lane 3) of the GST–22-kDa fusion protein following cleavage. The arrow indicates the presence of the 22-kDa protein of M. bovis BCG.