Development of a POC test for TB based on multiple immunodominant epitopes of M. tuberculosis specific cell-wall proteins

PLoS One. 2014 Sep 23;9(9):e106279. doi: 10.1371/journal.pone.0106279. eCollection 2014.

Abstract

The need for an accurate, rapid, simple and affordable point-of-care (POC) test for Tuberculosis (TB) that can be implemented in microscopy centers and other peripheral health-care settings in the TB-endemic countries remains unmet. This manuscript describes preliminary results of a new prototype rapid lateral flow TB test based on detection of antibodies to immunodominant epitopes (peptides) derived from carefully selected, highly immunogenic M. tuberculosis cell-wall proteins. Peptide selection was initially based on recognition by antibodies in sera from TB patients but not in PPD-/PPD+/BCG-vaccinated individuals from TB-endemic settings. The peptides were conjugated to BSA; the purified peptide-BSA conjugates striped onto nitrocellulose membrane and adsorbed onto colloidal gold particles to devise the prototype test, and evaluated for reactivity with sera from 3 PPD-, 29 PPD+, 15 PPD-unknown healthy subjects, 10 patients with non-TB lung disease and 124 smear-positive TB patients. The assay parameters were adjusted to determine positive/negative status within 15 minutes via visual or instrumented assessment. There was minimal or no reactivity of sera from non-TB subjects with the striped BSA-peptides demonstrating the lack of anti-peptide antibodies in subjects with latent TB and/or BCG vaccination. Sera from most TB patients demonstrated reactivity with one or more peptides. The sensitivity of antibody detection ranged from 28-85% with the 9 BSA-peptides. Three peptides were further evaluated with sera from 400 subjects, including additional PPD-/PPD+/PPD-unknown healthy contacts, close hospital contacts and household contacts of untreated TB patients, patients with non-TB lung disease, and HIV+TB- patients. Combination of the 3 peptides provided sensitivity and specificity>90%. While the final fully optimized lateral flow POC test for TB is under development, these preliminary results demonstrate that an antibody-detection based rapid POC lateral flow test based on select combinations of immunodominant M. tb-specific epitopes may potentially replace microscopy for TB diagnosis in TB-endemic settings.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacterial Proteins / immunology*
  • Cell Wall / immunology
  • Endemic Diseases / prevention & control
  • Humans
  • Immunodominant Epitopes / chemistry
  • Immunodominant Epitopes / isolation & purification*
  • Mycobacterium tuberculosis / immunology
  • Mycobacterium tuberculosis / metabolism*
  • Point-of-Care Systems
  • Sensitivity and Specificity
  • Serum Albumin, Bovine / chemistry
  • Tuberculin Test / economics
  • Tuberculin Test / methods*
  • Tuberculosis, Pulmonary / blood
  • Tuberculosis, Pulmonary / diagnosis*
  • Tuberculosis, Pulmonary / immunology
  • Tuberculosis, Pulmonary / microbiology

Substances

  • Bacterial Proteins
  • Immunodominant Epitopes
  • Serum Albumin, Bovine