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Open Access Research article

Evaluation of the clinical value of ELISA based on MPT64 antibody aptamer for serological diagnosis of pulmonary tuberculosis

Changtai Zhu12, Jinming Liu3, Yang Ling1, Hua Yang2, Zhonghua Liu2, Ruijuan Zheng2, Lianhua Qin24* and Zhongyi Hu24*

Author Affiliations

1 Department of Medical Laboratory, Changzhou Tumor Hospital Soochow University, Changzhou, 213001, China

2 Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, 200433, China

3 Department of Respiratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, 200433, China

4 Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, No. 507 Zhengmin Rd, Shanghai, 200433, People's Republic of China

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BMC Infectious Diseases 2012, 12:96  doi:10.1186/1471-2334-12-96

Published: 20 April 2012

Abstract

Background

Presently, tuberculosis (TB) poses a global threat to human health. The development of reliable laboratory tools is vital to the diagnosis and treatment of TB. MPT64, a protein secreted by Mycobacterium tuberculosis complex, is highly specific for TB, making antibody to MPT64 a reagent specific for the diagnosis of TB.

Method

Antibody to MPT64 was obtained by a combination of genetic engineering and immunization by the system evolution of ligands by exponential enrichment. A high-affinity aptamer of antibody to MPT64 was selected from a random single-stranded DNA library, and a sandwich ELISA method based on this aptamer was developed. This ELISA method was used to detect TB in 328 serum samples, 160 from patients with pulmonary TB (PTB) and 168 from non-tuberculous controls.

Results

The minimum limit of detection of the ELISA method was 2.5 mg/L, and its linear range varied from 10 mg/L to 800 mg/L. Its sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and area under the curve, with 95 % confidence intervals, were 64.4 % (56.7 %–71.4 %), 99.4 % (96.7 %–99.9 %), 108.2 (15.3–765.9), 0.350 (0.291–0.442) and 0.819 (0.770–0.868), respectively. No significant difference in sensitivity was observed between sputum smear positive (73/112, 65.2 %) and negative (30/48, 62.5 %) individuals.

Conclusions

This sandwich ELISA based on an MPT64 antibody aptamer may be useful for the serological diagnosis of PTB, both in sputum smear positive and negative patients.

Keywords:
MPT64 antibody; System evolution of ligands by exponential enrichment (SELEX); ssDNA; Aptamer; Tuberculosis