Yonsei Med J.  2020 Sep;61(9):789-796. 10.3349/ymj.2020.61.9.789.

Diagnostic Potential of a PPE Protein Derived from Mycobacterium tuberculosis Beijing/K Strain

• Kim A
• Park KJ
• Kim YS
• Cho SN
• Dockrell HM
• Hur YG

• KMID: 2505379
• DOI: http://doi.org/10.3349/ymj.2020.61.9.789

Abstract

Purpose
The prevalence of Mycobacterium tuberculosis (M. tb) and the status of M. bovis BCG vaccination may affect host immune responses to M.tb antigens. Understanding of the predominant local M. tb strain and immune signatures induced by its strain-specific antigens may contribute to an improved diagnosis of tuberculosis (TB). The aim of this study was to determine immune responses to M. tb antigen which was identified from the hyper-virulent Beijing/K strain in South Korea.
Materials and Methods
Pulmonary TB patients (n=52) and healthy subjects (n=92) including individuals with latent TB infection (n=31) were recruited, and QuantiFERON-TB Gold In-Tube tests were performed. The Beijing/K-antigen specific immune signatures were examined by diluted whole blood assays and multiplex bead arrays in a setting where nationwide BCG vaccination is employed.
Results
Statistical analyses demonstrated that three [C-X-C motif chemokine (CXCL10), interleukin (IL)-6, interferon (IFN)-α] of 17 cytokines/chemokines distinguished active cases from healthy controls following stimulation with the Beijing/K-specific antigen. IFN-α also differentiated between active diseases and latent TB infection (p<0.01),and the detection rate of TB was dramatically increased in combination with IL-6 and CXCL10 at the highest levels of specificity (95–100%).
Conclusion
Our data indicate that immune signatures to the M. tb Beijing/K-specific antigen can provide useful information for improved TB diagnostics. The antigen may be developed as a diagnostic marker or a vaccine candidate, particularly in regions where the M. tb Beijing/K strain is endemic.

Keyword

Mycobacterium tuberculosis; M. bovis BCG; Beijing/K; CXCL10; IL-6; IFN-α