ABSTRACT
Objective To evaluate the antigenicity of two proteins of Mycobacteium tuberculosis (M. tuberculosis), Dnak(Rv0350) and MPT83(Rv2873), in order to provide a scientific basis for immuno-logical diagnosis of tuberculosis and research on vaccines. Methods The two antigen proteins, Dnak (Rv0350) and MPT83(Rv2873), were cloned, expressed and purified using the methods of genetic recom-bination and protein purification technology. Blood samples were collected from subjects including tuberculo-sis patients ( TB) , non-tuberculosis patients with other pulmonary diseases ( non-TB) and healthy volunteers (HV). To analyze the immunological properties of the recombinant Dnak (Rv0350) and MPT83 (Rv2873) proteins, they were used as antigens to detect humoral and cellular immunity in the subjects with enzyme linked immunosorbent assay ( ELISA ) and effector T cell enzyme-linked immunospot assay ( ELISPOT ) . Results The recombinant and purified Dnak (Rv0350) and MPT83 (Rv2873) proteins of M. tuberculosis were successfully obtained and used as antigens in the detection of humoral and cellular immunity in the sub-jects. Specific antibodies ( IgG) in the serum samples of 135 TB, 56 non-TB and 94 HV were tested with ELISA. The results showed that the sensitivity, specificity and accuracy of Dnak ( Rv0350 ) protein were 77. 80％ (105/135), 56. 70％ (85/150) and 66. 67％ (190/285). Similarly, the sensitivity, specificity and accuracy of MPT83 (Rv2873) protein were 76. 30％ (103/135), 43. 30％ (65/150) and 58. 95％(168/285). Cellular immunity was tested with the levels of IFN-γproduced by effector T lymphocytes after stimulating peripheral blood monouclear cells ( PBMC) collected form subjects of 59 TB, 65 non-TB and 64 HV with Dnak (Rv0350) and MPT83 (Rv2873) protein antigens. The results showed that the sensitivity, specificity and accuracy of Dnak (Rv0350) and MPT83 (Rv2873) proteins were 66. 10％ (39/59), 62. 79％ (81/129) and 63. 83％ (120/188), and 47. 46％ (28/59), 79. 84％ (103/129) and 69. 68％(131/188), respectively. Conclusions M. tuberculosis Dnak (Rv0350) and MPT83 (Rv2873) proteins have good antigenicity and could stimulate T cells to produce stronger immune responses. The two proteins used in combination might have promising potential in the research of immunodiagnosis of tuberculosis and the development of new anti-tuberculosis vaccines.