M. tb Rv3339c (ICD-1) and Rv0066c (ICD-2) are expressed at the protein level. Antibody response to M. tb ICD-1 and ICD-2 was determined by ELISA. Sample representation of ten M. tb patient sera out of 125 showing high immunogenic response when compared with healthy controls. Y axis represents absorbance values at 492λ and X axis represents random patient sera tested for M. tb ICD-1 and ICD-2 antigenic response. 1 – 10, antigen ICD-1; 11 – 20, antigen ICD-2; 21 – 25, Healthy controls for ICD-1; 26 – 3, Healthy controls for ICD-2. Inset: Affinity purification of M. tb ICD-1 and M. tb ICD-2. The different lanes are: lanes 1: M. tb ICD-1; lane M: protein molecular size markers (200 kDa, 116 kDa, 97 kDa, 66 kDa, 45 kDa, 31 kDa and 21.5 kDa); lanes 2: M. tb ICD-2.