If a subject has previously received an adequate course of therapy for either latent (9 months of isoniazid in a locale where rates of primary multi drug resistant TB infection are <5% or an acceptable alternative regimen) or active (acceptable multi drug regimen) TB infection, neither a PPD test nor a QuantiFERON-Gold®TM test need be obtained. A chest radiograph should be obtained if not done within the 3 months prior to screening. To be considered eligible for the study, the chest radiograph must be negative for active tuberculosis infection.