Clinical Microbiology: Open Access

Serodiagnostic potential of immuno-PCR using mycobacterial antigen 85B, ESAT-6 and cord factor in pulmonary and extrapulmonary tuberculosis patients

3^rd Global Microbiologists Annual Meeting

August 15-17, 2016 Portland, Oregon, USA

Promod Mehta

Maharshi Dayanand University, India

Posters & Accepted Abstracts: Clin Microbiol

Abstract:

Rapid and accurate diagnosis of tuberculosis (TB) is essential to control the disease. A novel immuno-polymerase chain reaction (immuno-PCR; I-PCR) assay was developed for the detection of mycobacterial antigen 85B (Ag85B, Rv1886c) and its antibodies in pulmonary TB (PTB) and extrapulmonary TB (EPTB) patients and the results were compared with an analogous enzymelinked immunosorbent assay (ELISA). The amino modified reporter DNA was covalently attached with the antibody through a heterobifunctional cross linking agent succinimidyl 4-[N-maleimidomethyl]-cyclohexane-1-carboxylate (SMCC). The detection limit of Ag85B by indirect sandwich I-PCR was found to be 1 fg/mL, which were 106-fold lower than ELISA. The sensitivities of 85% and 77% with I-PCR and 77.6% and 62.5% with ELISA were observed in smear positive and smear negative PTB cases, respectively with high specificity (86-90%). On the other hand, sensitivities of 84% and 63.7% with I-PCR and 68% and 47.5% with ELISA were observed in confirmed and clinically suspected EPTB cases, respectively with high specificity (92-96%). An indirect I-PCR was also developed for the detection of circulating anti-Ag85B, anti-ESAT-6 (early secretory antigenic target-6, Rv3875) and anti-cord factor (trehalose-6,6' dimycolate) antibodies from the sera samples of PTB and EPTB patients. The detection of cocktail of anti-Ag85B, anti- ESAT-6 and anti-cord factor antibodies was found to be superior to the detection of individual antibodies. Based on the detection of cocktail of antibodies, sensitivities of 89.5% and 77.5% with I-PCR and 70.8% and 65% with ELISA were observed in smear positive and smear negative PTB cases, respectively with high specificity; whereas a sensitivity of 77.5% with I-PCR and 65% with ELISA was observed in EBTB cases. The detection of mycobacterial Ag85B and cocktail of antibodies by I-PCR in the study is likely to improve the utility of existing algorithms for TB diagnosis.

Biography :

Email: pkmehta3@hotmail.com