Antigenic characterization of Mycobacterium bovis BCG culture filtrate

Mycobacterium bovis BCG culture filtrate, on gelfiltration chromatography revealed four prominent regions. Of these 4, region II possessed the highest antigenic reactivity by enzyme-linked immunosorbent assay (ELISA) and delayed type hypersensitivity (DTH) skin testing in guinea pigs. On anion-exchange chromatography, region II was resolved into 5 prominent fractions of which fraction II was found to have the highest antigenic reactivity. On sodium dodecylsulphate-polyacrylamide gel electrophoresis (SDS-PAGE), M. bovis BCG culture filtrate revealed 11 structural polypeptides. Fraction II yielded a homogenous polypeptide of 15.3 kDa molecular weight. All fractions cross-reacted with various mycobacteria used in this study except a 15.3 kDa polypeptide which was specific to M. bovis BCG.