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Open Access Research article

IgG, IgM and IgA antibodies against the novel polyprotein in active tuberculosis

Xiaoyan Feng1, Xiqin Yang1, Bingshui Xiu1, Shuang Qie1, Zhenhua Dai1, Kun Chen1, Ping Zhao2, Li Zhang3, Russell A Nicholson4, Guohua Wang1, Xiaoguo Song1 and Heqiu Zhang1*

Author Affiliations

1 Department of Bio-diagnosis, Beijing Institute of Basic Medical Sciences, Beijing 100850, China

2 Chaoyang District Centre for Disease Control and Prevention, Beijing 100029, China

3 Tianjin Haihe Hospital, Tianjin 300350, China

4 Department of Biological Sciences, Simon Fraser University, Burnaby, B.C V5A 1S6, Canada

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BMC Infectious Diseases 2014, 14:336  doi:10.1186/1471-2334-14-336

Published: 17 June 2014

Abstract

Background

The present study was aimed to evaluate whether IgG, IgM and IgA antibodies levels detected against a novel Mycobacterium tuberculosis polyprotein 38 F-64 F (with 38 F being the abbreviation for 38kD-ESAT6-CFP10 and 64 F for Mtb8.4-MPT64-TB16.3-Mtb8) are suitable for diagnosing active tuberculosis, and for monitoring the efficacy of chemotherapy on TB patients.

Methods

In this study, a total of 371 active TB patients without treatment were selected and categorized into S+/C+ group (n = 143), S-/C+ group (n = 106) or S-/C- group (n = 122). A series of serum samples were collected from 82 active TB patients who had undergone anti-TB chemotherapy for 0–6 months at one month interval. Humoral responses (IgG, IgM and IgA) were determined for the novel Mycobacterium tuberculosis polyprotein using indirect ELISA methods in all of serum samples.

Results

For S+/C+, S-/C+ and S-/C- active tuberculosis patients before anti-TB chemotherapy, the sensitivities of tests based on IgG were 65.7%, 46.2% and 52.5% respectively; the sensitivities based on IgM were 21.7%, 24.5% and 18.9%; and the sensitivities based on IgA were 25.2%, 17.9% and 23.8%. By combination of three isotypes, for all active tuberculosis patients, the test sensitivity increased to 70.4% with the specificity being 91.5%. After anti-TB chemotherapy, there were no significant differences between groups with different courses of anti-TB chemotherapy.

Conclusions

The novel Mycobacterium tuberculosis polyprotein 38 F-64 F represents potential antigen suitable for measuring IgG, IgM and IgA antibodies. However, the serodiagnostic test based on the 38 F-64 F polyprotein appears unsuitable for monitoring the efficacy of chemotherapy.

Keywords:
Tuberculosis; Serodiagnosis; Polyprotein