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

PURPOSE

The prevalence of () and the status of BCG vaccination may affect host immune responses to antigens. Understanding of the predominant local 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 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 (<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 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 Beijing/K strain is endemic.