title: An integrated surrogate model for screening of drugs against Mycobacterium tuberculosis.
abstract: OBJECTIVE
  The intracellularly surviving and slow-growing pathogen, Mycobacterium tuberculosis, adapts the host cell environment for its active and dormant life cycle. It is evident that the lack of appropriate high-throughput screening of inhibitors within host cells is an impediment for the early stages of anti-tubercular drug discovery. We aimed to develop an integrated surrogate model that enhances the screening of large inhibitor libraries.
  
  
  METHODS
  Different mycobacterial species were compared for their growth, drug susceptibility and intracellular uptake. A 6-well plate solid agar-based spot culture growth inhibition (SPOTi) assay was developed into a higher throughput format. The uptake and intracellular survival of Mycobacterium aurum within mouse macrophage cells (RAW 264.7) were optimized using 24/96-well plate formats.
  
  
  RESULTS
  Fast-growing, non-pathogenic M. aurum was found to have an antibiotic-susceptibility profile similar to that of M. tuberculosis. The sensitivity to an acidic pH environment and the ability to multiply inside RAW 264.7 macrophages provided additional advantages for employing M. aurum in intracellular drug screening methods. A selection of anti-tubercular drugs inhibited the growth and viability of M. aurum inside the macrophages at different levels.
  
  
  CONCLUSIONS
  We present a rapid, convenient, high-throughput surrogate model, which provides a comprehensive evaluation platform for new chemical scaffolds against different physiological stages of mycobacteria within the primary cell environment of the host. The results using anti-tubercular drugs validate this model for screening libraries of existing and novel chemical entities.
authors.affiliation: Mycobacteria Research Laboratory, Department of Biological Sciences,  Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX,  UK.
authors.forename: Antima
authors.initials: A
authors.lastname: Gupta
authors.forename: Sanjib
authors.initials: S
authors.lastname: Bhakta
mesh_terms: D000818:Animals; D000995:Antitubercular Agents / Q000302:isolation & purification* / Q000494:pharmacology*; D002460:Cell Line; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D057166:High-Throughput Screening Assays / Q000379:methods; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D008826:Microbial Sensitivity Tests / Q000379:methods; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000254:growth & development
chemical_list: D000995:Antitubercular Agents