The performance of the diagnostic test was evaluated in approx 100 cerebrospinal fluid samples obtained from paediatric subjects, and for pulmonary over 300 tests have been conducted so far, said Dr. Tarun Kumar Sharma from the Centre for Biodesign and Diagnostics at Translational Health Science and Technology Institute (THSTI), Faridabad.
The diagnostic test is based on a derivative of a DNA aptamer (a small single-stranded DNA molecule that binds to a specific target molecule and is a chemical rival of antibodies) that shows high binding affinity in nanomolar range and high specificity to a TB antigen (HspX). Besides higher binding affinity, there is significantly higher load of the HspX antigen in cerebrospinal fluid samples, leading to higher sensitivity.
A rapid, point-of-care diagnostic test for TB meningitis that uses the DNA aptamer has already been adapted to a sensor format and is being evaluated on clinical samples. "It takes all of 30 minutes to get the result as we are using an electrochemical sensing platform. The test which will cost around Rs 300 only is being done in AIIMS and RML hospital in Delhi," says Prof. Tyagi.
The aptamer-based diagnostic test for TB meningitis has been patented by AIIMS and THSTI and licensed to AptaBharat Innovation Pvt Limited, a THSTI spin-off founded by Dr Sharma.
"The currently used diagnostic methods microscopy and culture of cerebrospinal fluid suffer from huge limitations in terms of poor sensitivity and long turnaround time of up to eight weeks, said the official.