Cloning, expression and immunological evaluation of a short fragment from Rv3391 of Mycobacterium tuberculosis

Tuberculosis (TB) is still one of the greatest health care problems in the world. In order to identify antigens that may be used in the serodiagnosis of active tuberculosis, a short fragment from Rv3391 (fRv3391) of Mycobacterium tuberculosis was cloned and expressed. Its molecular weight and secondary structure elements were identified by mass spectrometry and circular dichroism. And its immunological nature was also evaluated by enzyme-linked immunosorbent assay (ELISA). The fRv3391 was expressed in Escherichia coli BL21 (DE3) with the molecular weight of 42.5 kDa and the secondary structure elements 36.2% α-helix, 0.0% β-sheet, 32.6% β-turn, and 31.3% random coil. Evaluation of fRv3391 as an ELISA solid-phase antigen on a set of human sera from well-characterized TB cases and healthy subjects revealed that there was strong serum antibody reactivity to fRv3391 in many human TB patients. Taken together, a short fragment from Rv3391 of Mycobacterium tuberculosis was cloned and expressed and the ELISA results showed that the protein may be useful as an immunodominant antigen for the serodiagnosis of active TB.