RESUMO
OBJECTIVE: To establish a simple, fast and accurate double antigen colloidal gold immunochromatographic technique for detecting Mycobacterium tuberculosis antibody from tuberculosis patients. METHODS: The fusion protein ESAT-6-16-38 was constructed by using gene cloning technique for the 6, 16 and 38 kDa early secreted antigenic target from Mycobacterium tuberculosis. The ESAT-6-16-38 fusion protein was marked to colloidal gold to establish the double antigen colloidal gold immunochromatographic assay. Serum samples from 163 patients with tuberculosis, including 57 sputum-positive cases, 64 sputum-negative cases, and 42 cases with extrapulmonary tuberculosis, were collected during 2007 and 2009 from the Disease Prevention and Control Center of Deqing County. In addition, 573 controls (224 healthy volunteers, 217 patients with acute pneumonia and bronchitis, 132 patients with paragonimiasis) were recruited for comparison. Mycobacterium tuberculosis specific antibodies were detected by using immunochromatographic and protein chip technique. Detection rate was compared with Chi-square test. RESULTS: Among the 163 tuberculosis patients, the positive rates of immunochromatographic detection and protein chip were 73.0% (120/163) and 72.4% (118/163) respectively; the difference was not statistically significant (χ()2 = 0.062, P > 0.05). Among the 573 controls, the negative rates of immunochromatographic detection and protein chip were 93.9% (538/573) and 92.0% (527/573) respectively; the difference was not statistically significant (χ()2 = 0.635, P > 0.05). There was no cross reaction in the paragonimiasis patients. The positive rate of the immunochromatographic assay was as high as 87.7% (50/57) in the sputum-positive patients. CONCLUSIONS: The double antigen immunochromatographic technique is an easy to operate, rapid, highly sensitive, specific, and reproducible method for the detection of Mycobacterium tuberculosis antibodies.
