IFNG and infection: TNF-α in synergy with IFN-γ induce antimycobacterial activity of macrophages and increases its bactericidal activity.6 Till date, several polymorphisms within the promoter region of TNF-α and IFN-γ gene have been shown to be associated with susceptibility or resistance to TB in different ethnic groups.7,8,9,10 In contrast, the role of genetic variability of M. tuberculosis in the outcome of the infection remains to be uncertain.11 Most of immunological research on tuberculosis has been performed with laboratory strains i.e., H37RV and Erdman.