Fig 1. Coomassie blue stained Bis-Tris gel showing 7 PPD preparations.

Note the striking differences in traditional production PPDs (lanes 2, 4 and 5 for example) in comparison to the alternative production method (lanes 6 and 7). Lane assignments include: 1 and 10-protein standards; 2-Lot #9801 PPD; 3-Lot 9801 at a 1:10 dilution; 4-Lot 0802; 5-Lot 0803A; 6-Lot 0902A; 7-Lot 0902B; 8-M. bovis PPD; 9 –M. avium PPD. Molecular mass standards are indicated in the left margin in kilodaltons.