Antibodies against native proteins of Mycobacterium tuberculosis can detect pulmonary tuberculosis patients

Accurate point-of-care testing (POCT) is critical for managing tuberculosis (TB). However, current antibody-based diagnosis shows low specifcity and sensitivity. To fnd proper antigen candidates for TB diagnosis by antibodies, we assessed IgGs responsiveness to Mycobacterium tuberculosis proteins in pulmonary TB (PTB) patients. We employed major secreted proteins, such as Rv1860, Ag85C, PstS1,
Rv2878c, Ag85B, and Rv1926c that were directly purifed from M. tuberculosis. In the frst screening, we found that IgG levels were signifcantly elevated in PTB patients only against Rv1860, PstS1, and Ag85B among tested antigens. However, recombinant PstS1 and Ag85B from Escherichia coli (E. coli) couldn’t distinguish PTB patients and healthy controls (HC). Recombinant Rv1860 was not checked
due to its little expression. Then, the 59 confrmed PTB patients from Soetomo General Academic Hospital, Surabaya, Indonesia, and 102 HC were tested to Rv1860 and Ag85B only due to the low yield of the PstS1 from M. tuberculosis. The ROC analysis using native Ag85B and Rv1860 showed an
acceptable area under curve for diagnosis, which is 0.812 (95% CI 0.734–0.890, p < 0.0001) and 0.821 (95% CI 0.752–0.890, p < 0.0001). This study indicates that taking consideration of native protein structure is key in developing TB’s POCT by antibody-based diagnosis.