Group of Indian Researcher Develop the Rapid test for detection of Tuberculosis.
A group of researcher from Translational Health Science & Technology Institute, Faridabad and All India Institute of Medical Sciences, New Delhi jointly develop highly sensitive and quick detection tests for detection of TB (tuberculosis) infection in lungs and surrounding membranes. Current tests either have low sensitivity or are time consuming.
Tuberculosis is one of the world's leading infectious killers - second only to HIV/AIDS. The 2007 WHO Global TB Control Report, which will be issued on Thursday 22 March 2007, updates the current trends on the airborne disease with all the very latest data from nearly 200 countries.
The bacteria that cause TB are spread when an infected person coughs or sneezes.
Most people infected with the bacteria that cause tuberculosis don't have symptoms. When symptoms do occur, they usually include a cough (sometimes blood-tinged), weight loss, night sweats and fever.
Treatment isn't always required for those without symptoms. Patients with active symptoms will require a long course of treatment involving multiple antibiotics, TB claims more than 1 million cases in each year in India. Early detection and treatment are very important to prevent the spreading of tuberculosis, outbreaks, and development of Tuberculosis. Researcher at the Translational Health Science and Technology Institute at Faridabad and All India Institute of Medical Sciences(AIIMS), New Delhi have jointly developed highly sensitive and Quick tests for detection of tuberculosis infection in lungs and surrounding membranes.
TB is spread from one person to another through the air. When a person with TB of the lungs or throat coughs, sneezes, sings or talks, droplets containing the bacteria are released into the air. When the bacteria attack the lungs, the disease manifests itself as pulmonary form.
Too many people have undetected TB for too long; late detection of TB increases their risk of transmitting the disease to others, having poor health outcomes, or that they and their family will suffer distress and economic hardship.
Till now, detection of all forms of TB is mostly based on two principal pathways to early TB case detection. The most important is the “patient-initiated pathway”, which starts with a person with TB actively seeking care when experiencing symptoms. The second pathway - the “screening pathway” - refers to the active identification of persons with suspected TB among people who do not actively seek care for symptoms or signs compatible with TB.
The most commonly used diagnostic tool for tuberculosis is a simple skin test, though blood tests are becoming more commonplace.
The Indian researchers have now developed two DNA aptamer-based tests - Aptamer Linked Immobilized Sorbent Assay (ALISA) and Electrochemical Sensor (ECS) for detection of a bacterial protein in the sputum of suspected patient to address the shortcomings in the present testing protocol. Aptamers are single-stranded DNA or RNA (ssDNA or ssRNA) molecules. Aptamers assume a variety of shapes due to their tendency to form helices and single-stranded loops. that bind to specific molecular targets. They are known to bind the right target (which defines sensitivity) and at the same time rule out any non-specific binding to other targets (specificity).
The performance of the newly developed tests was compared with antibody-based tests in 314 sputum samples. ALISA showed 92% sensitivity while the antibody-based method was 68% sensitive. The research group used ALISA to detect a bacterial protein, HspX. This method, however, took five hours to yield results because it requires sputum immobilization which is time-consuming step. So the team made efforts to develop a simplified ECS test.
In this, aptamer was immobilized with an electrode and upon binding to HspX in the sputum sample, a drop in the electrical signal was recorded. The ECS test can be used for screening of samples in the field as it takes as less as 30 minutes to deliver results. It is highly sensitive and could detect HspX protein in 91% of the samples tested in this study. In addition, there is no need for sputum sample preparation which is a complex and time-consuming process.
Tarun sharma said "We aim to develop aptamers for detection of multiple bacterial proteins simultaneously which is expected to lead a more robust test," "The aptamer-based screening tests for pulmonary TB, pleural TB, and TB meningitis hold immense promise for a country like India, where the disease burden in high and primary health care is only a dream for many.
The group used aptamer-based test also for detection of pleural TB, the second most prevalent form of extrapulmonary TB. Early diagnosis of pleural TB is limited by availability of a sensitive and rapid test. The performance of existing DNA-based tests varies widely due to low bacterial load in pleural fluid sample. "There is no test for making a confirmed diagnosis of pleural TB. Even WHO-endorsed Gene Xpert has a poor sensitivity of 22%. On the contrary, our aptamer-based test for pleural TB has showed 93% sensitivity and is cost-effective," explained Sagarika Haldar, a member of the research team, while speaking to India Science Wire.
The researchers team were lead by Dr. Jaya Tyagi (AIIMS), Dr. Tarun Sharma and Dr. Sagarika Haldar (THSTI) and included Researcher, peoples and patient from both the institutes. The pulmonary TB results were published in journal ACS Infectious Diseases and the pleural TB results were published in Analytical Biochemistry.
Original Article taken from : Indian science wire