Evaluation of Mycobacterium tuberculosis fusion protein with ELISA in serological diagnosis

Objective To study on applied value of recombinant ESAT6-38kDa-16kDa fusion protein in serological diagnosis of tuberculosis(TB) and to compare the results to imported protein lipoarabinomannan(LAM) and tuberculosis protein chip system.Methods Using ESAT6-38kDa-16kDa fusion protein and imported LAM protein as antigen and staphylococcal protein A linked to horseradish peroxidase (SPA-HRP) as the antibody,the serum of pulmonary tuberculosis patients,extrapulmonary tuberculosis patients and normal human were detected with indirect enzyme-linked immunosorbent assay(ELISA) then the value in serodiagnosis of TB were assessed.Results The indirect ELISA method for the detection of TB specific antibody in serum was established,with the optional antigen concentrations of 1 μg/mL and 0.5 μg/mL for ESAT6-38kDa-16kDa and ManLAM,and optimal serum and SPA-HRP dilution of 1:100 and 1:4000.The sensitivity and specificity of the assay were 76.9% and 89.2%,respectively.There was no significant difference in comparison with the results of LAM (P > 0.05).There was no significant difference in the positive and negative coincidence rate of the method in comparison with tuberculosis protein chip system based on the detection of 68 serum samples of pulmonary tubercuosis patients(χ²=0.018,P > 0.05).Conclusion This recombinant fusion protein may be used as an effective antigen in serodiagnosis of TB and helpful in developing new specific diagnostic test.