Non-sputum-based
biomarker assay is urgently required as per WHO's target product pipeline for diagnosis of
tuberculosis. Therefore, the current study was designed to evaluate the utility of previously identified
proteins, encoded by in vivo expressed mycobacterial transcripts in
pulmonary tuberculosis, as diagnostic targets for a serodiagnostic assay. A total of 300 subjects were recruited including smear+, smear-
pulmonary tuberculosis (PTB) patients,
sarcoidosis patients,
lung cancer patients and healthy controls.
Proteins encoded by eight in vivo expressed transcripts selected from previous study including those encoded by two topmost expressed and six RD transcripts (Rv0986, Rv0971, Rv1965, Rv1971, Rv2351c, Rv2657c, Rv2674, Rv3121) were analyzed for
B-cell epitopes by
peptide arrays/bioinformatics.
Enzyme-linked
immunosorbent assay was used to evaluate the antibody response against the selected
peptides in sera from PTB and controls. Overall 12
peptides were selected for serodiagnosis. All the
peptides were initially screened for their antibody response. The
peptide with highest sensitivity and specificity was further assessed for its serodiagnostic ability in all the study subjects. The mean absorbance values for antibody response to selected
peptide were significantly higher (p<0.001) in PTB patients as compared to healthy controls; however, the sensitivity for diagnosis of PTB was 31% for smear+ and 20% for smear- PTB patients. Thus, the
peptides encoded by in vivo expressed transcripts elicited a significant antibody response, but are not suitable candidates for serodiagnosis of PTB.