Objectives: Beijing strain of Mycobacterium tuberculosis (M. tb) is characterized by a high incidence of transmission, relapse, and drug resistance. This study aimed to determine host immune responses to antigens derived from the Beijing/K strain which has been highly prevalent in tuberculosis (TB) outbreaks in South Korea. Methods: We recruited 52 TB patients and 96 healthy subjects comprising 31 individuals with latent TB infection (LTBI) and 65 TB-naïve controls based on QuantiFERON-TB Gold In-Tube (QFT-IT) tests. Blood samples were obtained for diluted whole-blood assays, multiplex bead arrays, ELISpot assays, and HLA typing. Molecular genotyping of M. tb was performed using clinical isolates. Results: Active TB and LTBI groups were differentiated by TNF-α concentrations induced by the Beijing/K strain-derived antigens, MTBK_24790 and MTBK_24800 (P < 0.001). MTBK_24800-induced IFN-γ and CXCL10 concentrations discriminated the TB-infected groups from TB-naïve controls (P < 0.001). IFN-γ-producing T cells were generated in 87.2% of TB patients in response to MTBK_24800 peptide antigens. The major immunogenic epitope was at C-terminal of the antigen, and predominantly recognized by HLA-DR4 and -DQ4. Conclusions: Measurement of IFN-γ, CXCL10, and TNF-α concentrations induced by MTBK_24790 and MTBK_24800 may contribute to improved diagnosis of TB and vaccine development in regions where the Beijing/K strain is endemic.
Bibliographical noteFunding Information:
We are grateful to our study participants and staff at Ajou University Hospital in Suwon, South Korea for their assistance. We also thank Hyejin Kim and Seungsook Sohn for their help with HLA typing, and Youngmi Kim for her aid in transferring samples for M. tb genotyping. This work was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI14C1324 ). The funders had no role in design of the study, analysis and interpretation of the data, and decision to publish the study.
© 2016 The British Infection Association.
All Science Journal Classification (ASJC) codes
- Microbiology (medical)
- Infectious Diseases