Differential expression of a unique protein by intracellular Mycobacteriumtuberculosis complex

We have investigated the changes in the protein synthesis pattern in guinea pig peritoneal macrophages following infection with virulent Mycobacterium tuberculosis H37Rv in vitro. By S-35 methionine labelling of the newly syn thesized proteins followed by ultracentrifugation, SDS-PAGE (sodium dodecyl sulphate polyacrylamide gel electrophoresis) and auto radiography, the pro tein synthesis pattern of the control uninfected macrophages and the infect ed macrophages in vitro were compared. By adding cycloheximide to the macro phage cultures, the protein synthesis of macrophages was inhibited and the protein synthesis pattern of M. tuberculosis has been analysed. We have ide ntified a mycobacterial protein of molecular weight 17 kDa which was expres sed exclusively in the cytosolic fraction of M. tuberculosis-infected guine a pig macrophages in vitro.