A new Mycobacterium tuberculosis smooth colony reduces growth inside human macrophages and represses PDIM Operon gene expression. Does an heterogeneous population exist in intracellular mycobacteria?

► Two MTB colony phenotypes appear only after infection of human macrophages. ► The smooth phenotype lacks the outermost capsule but retain its AFB feature. ► The smooth phenotype grows less in human macrophages than wild type. ► The new MTB colony dramatically represses gene expression while inducing mprA gene. ► MTB intracellular population might become heterogeneous to face host's response.