Abstract
Mice were infected intravenously with 0.5mg of a virulent strain of M. bovis. The lungs were separated from the moribund mice 3 to 4 weeks after infection. The lungs from 640 mice were homogenized and the bacilli removed therefrom by sequential centrifugation. The supernatant was heated at 120C for 20 min and subjected to filtration and centrifugation to remove the denatured and aggregated materials. The supernatant was then fractionated with ammonium sulfate at 50%-saturation, by gel-filtration on a Sephadex G-100 column and by chromatography on a DEAE-cellulose column, The protein fraction finally obtained had a high tuberculin activity and behaved like PPD in disc electrophoresis in polyacrylamide gel.
