Green fluorescent protein as a reporter in rapid screening of antituberculosis compounds in vitro and in macrophages

The development of new drugs against Mycobacterium tuberculosis is impeded by slow growth and highly infectious nature of the organism that warrants t he need to work under highly stringent biosafety conditions. These problems can be overcome by use of reporter genes and surrogate strains. A strain o f rapidly growing IM. aurum has been recommended as test organism to screen inhibitors of mycobacteria to preselect compounds for progression into tes ting against M. tuberculosis. We have investigated the application of recom binant M. aurum expressing green fluorescent protein in rapid screening of antituberculosis compounds in vitro and in infected macrophages. Recombinan t M: aurum[pGFM-11] expressing green fluorescent protein was constructed. T he assay is based on measurement of fluorescent intensity at 509 nm. A good correlation was found between fluorescence and growth. Fluorescence of rec ombinant IM. aurum was inhibited in vitro within 8 to 24 h by frontline ant imycobacterial drugs at their reported MICs whereas inhibition in infected macrophages was observed in 72 h. Therefore green fluorescent reporter syst em provides a convenient screen to test antimycobacterial compounds that ar e active in vitro and within infected macrophages. (C) 1998 Academic Press.