Screening and Assessing 11 Mycobacterium tuberculosis Proteins as Potential Serodiagnostical Markers for Discriminating {TB} Patients from {BCG} Vaccinees

摘要

Purified protein derivative (PPD) skin tests often yield poor specificity, so that to develop new serological antigens for distinguishing between Mycobacterium tuberculosis infection and Bacille Calmette-Guerin (BCG) vaccination is a priority, especially for developing countries like China. We predicted the antigenicity for selected open reading frames (ORFs) based on the genome sequences of M. tuberculosis {H37Rv} and M. bovis BCG, as well as their functions and differences of expression under different stimulus. The candidate {ORFs} were cloned from {H37Rv} sequences and expressed as recombinant proteins in Escherichia coli. We studied the serodiagnostic potential of 11 purified recombinants by using enzyme-linked immunosorbent assay (ELISA) and involving a cohort composed of 58 {TB} patients (34 males and 24 females), 8 healthy volunteers and 50 PPD-negative individuals before and after {BCG} vaccination. For all the 11 antigens, the median {OD} values for the sera from {TB} patients were statistically significantly higher than those for PPD-negative individuals before or after {BCG} vaccination (P<0.01). They had at least 92% specificity in healthy controls and six seroantigens (Rv0251c, Rvl973, Rv2376c, Rv2537c, Rv2785c and Rv3873A) were never reported with seroantigenicities previously. Thus the approach combining comparative genomics, bioinformatics and {ELISA} techniques can be employed to identify new seroantigens distinguishing M. tuberculosis infection from {BCG} vaccination.