1. Development of a POC test for TB based on multiple immunodominant epitopes of M. tuberculosis specific cell-wall proteins.
- Author
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Gonzalez JM, Francis B, Burda S, Hess K, Behera D, Gupta D, Agarwal AN, Verma I, Verma A, Myneedu VP, Niedbala S, and Laal S
- Subjects
- Cell Wall immunology, Endemic Diseases prevention & control, Humans, Immunodominant Epitopes chemistry, Mycobacterium tuberculosis immunology, Point-of-Care Systems, Sensitivity and Specificity, Serum Albumin, Bovine chemistry, Tuberculin Test economics, Tuberculosis, Pulmonary blood, Tuberculosis, Pulmonary immunology, Tuberculosis, Pulmonary microbiology, Bacterial Proteins immunology, Immunodominant Epitopes isolation & purification, Mycobacterium tuberculosis metabolism, Tuberculin Test methods, Tuberculosis, Pulmonary diagnosis
- 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.
- Published
- 2014
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