Accuracy of multitarget indirect enzyme-linked immunoassay assay for detection of tuberculosis antibody

Background: Diagnosis of tuberculosis (TB) is still difficult. The development of rapid and sensitive laboratory tools for the diagnosis of tuberculosis is a priority. This study aimed to develop an indirect enzyme-linked immunoassay (ELISA) assay for detection of TB antibody and explore its diagnostic value in patients with pulmonary tuberculosis (PTB) via a multi-center clinical evaluation. Methods: The specific antigen, fusion antigen, and specific antibody peptide were obtained using molecular cloning and phage peptide library screening. An indirect ELISA assay was developed using multiple target materials. Further, the assay was validated in six institutions with clinically confirmed TB patients, non-TB patients with pulmonary disease, and healthy controls as research subjects. Results: An indirect ELISA assay was developed with 16 kD antigen, 11,488 (CFP10-MPT48-TB8.4) fusion antigen, and TB18 and pl2 as target antigens against TB antibody. The results of this multicenter study showed that the sensitivity, specificity, and the area under the receiver operating characteristic curve (AUC) of the assay were 48.25% [95% confidence interval (CI): 45.5-51.1%], 92.20% (95% CI: 90.7-93.5%) and 0.724 (95% CI: 0.707-0.741), respectively, and the cut-off value was 0.119. According to the meta-analysis, the combined ROC was 0.736 (95% CI: 0.692-0.779), I-2=83.73%. The sensitivity of the sputum-positive PTB group (culture or smear positive) was 58.75% (95% CI: 52.96-65.00%); the sensitivity in sputum-negative group (culture or smear negative) was 37.38% (95% CI: 32.71-42.52%), respectively; the sensitivity of the sputum-positive group was significantly higher than that of sputum-negative group (OR=1.57, 95% CI: 1.29-1.92, P<0.001). Conclusions: Multitarget indirect ELISA assay based on specific-TB antigen, fusion antigen, and antibody peptide is of value for the diagnosis of PTB and can be used as an auxiliary rapid diagnostic tool to improve the sensitivity of sputum-negative TB.