COMPARISON OF CELLULAR AND EXTRACELLULAR PROTEINS EXPRESSED BY VARIOUS ISOLATES OF MYCOBACTERIUM-PARATUBERCULOSIS AND OTHER MYCOBACTERIAL SPECIES

Protein expression profiles of 10 isolates of Mycobacterium paratuberc ulosis, M avium 18 (formerly M paratuberculosis 18), and 1 isolate eac h of M avium serotype 2, M avium serotype 8, and M bovis BCG were exam ined. Protein expression profiles of M paratuberculosis and M avium we re similar. However, two-dimensional gel analysis of [S-35]methionine- labeled cellular proteins resolved 4 proteins, with molecular mass of 28,000, 32,000, 32,000, and 42,000 daltons, which were expressed in gr eater amounts in M paratuberculosis than in M avium. Two proteins, wit h molecular mass of 43,000 and 60,000 daltons, were identified, which were expressed in greater amounts in M avium than in M paratuberculosi s. Immune (western)-blot analysis, using antiserum from 2 cows clinica lly infected with M paratuberculosis as the primary antibodies, sugges ted that the 42,000-dalton protein may be specific for M paratuberculo sis. Comparison of protein expression profiles may be useful as a tool for differentiating isolates of M paratuberculosis. Sodium dodecyl su lfate-polyacrylamide gel electrophoresis of [S-35]methionine-labeled e xtracellular proteins revealed variability among the isolates. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of [S-35]methionine -labeled cellular proteins divided the M paratuberculosis isolates int o 2 groups on the basis of a difference in the amount of expression of a 28,000-dalton protein. This information may be useful in epidemiolo gic studies.