rt-LAMP Assay : SCIENCE & TECHNOLOGY

rt-LAMP Assay : SCIENCE & TECHNOLOGY

NEWS: Indigenous TB test can enhance accuracy, speed up testing

WHAT’S IN THE NEWS?

The rt-LAMP assay is a low-cost, rapid molecular test capable of detecting tuberculosis DNA in under 20 minutes with high sensitivity, even at low bacterial loads. Its ease of use and compatibility with existing PCR machines make it a vital tool in India’s TB elimination strategy.

What is rt-LAMP Assay?

  • rt-LAMP stands for Real-time Loop-mediated Isothermal Amplification, a rapid molecular diagnostic technique used for DNA detection.
  • It enables real-time amplification of DNA at a constant temperature, unlike conventional PCR which requires multiple temperature cycles.
  • In the context of tuberculosis (TB) detection, rt-LAMP offers a promising low-cost and rapid diagnostic alternative to traditional methods.
  • The test has received regulatory approval from the Central Drugs Standard Control Organisation (CDSCO) and is currently awaiting validation from the Indian Council of Medical Research (ICMR).

Key Features of rt-LAMP Assay

  • Low Cost:
  • Utilises inexpensive dyes such as Syto 16, a fluorescent marker, along with cost-effective primers.
  • Reduces financial burden compared to more expensive molecular tests like GeneXpert.
  • High Sensitivity:
  • Can detect as few as 10 copies of TB DNA per microliter in a sample, making it highly useful in early-stage or low-bacterial-load TB cases.
  • One-step Amplification:
  • Unlike RT-PCR which involves three temperature cycles (denaturation, annealing, extension), rt-LAMP works at a single isothermal temperature.
  • Simplifies testing logistics and reduces machine complexity.
  • Time-Efficient:
  • With its rapid amplification capabilities, results for positive samples can be generated within 10–20 minutes.
  • Facilitates faster clinical decisions and treatment initiation.
  • High Throughput:
  • Capable of processing 96 to 384 patient samples in a single batch, making it scalable for mass screening.
  • Open-Platform Compatibility:
  • Designed as an open system, the assay can be run using reprogrammed RT-PCR machines already available in labs, reducing the need for new infrastructure.

Why is rt-LAMP Significant for India?

  • As per the WHO Global TB Report 2023, India accounts for 27% of global TB cases, making it the highest TB burden country.
  • The National Strategic Plan (NSP) for TB Elimination 2017–2025 sets the goal of eliminating TB by 2025, five years ahead of the global SDG target.
  • A key pillar of the NSP is a shift from conventional microscopy to advanced molecular diagnostics, where rt-LAMP can play a transformative role.
  • rt-LAMP provides a cost-effective, rapid, and field-adaptable alternative to existing diagnostic tools, which is critical for India’s TB elimination mission.

Limitations of Existing TB Diagnosis Methods (Smear Microscopy)

  • Low Sensitivity: Especially in patients with low bacterial loads or those with HIV co-infection.
  • Cannot Detect Drug Resistance: Smear tests provide no insight into multi-drug resistant TB (MDR-TB) or rifampicin resistance.
  • Time-Consuming and Operator Dependent: Requires manual reading under microscopes, which can vary between technicians and facilities.
  • Despite these drawbacks, smear microscopy remains widely used in India due to its low cost and infrastructure familiarity.

Other Molecular Diagnostic Tools in Use for TB in India

  • GeneXpert:
  • Cartridge-based real-time PCR that detects Mycobacterium tuberculosis and rifampicin resistance.
  • Highly accurate and automated, but costly and less scalable for rural or mass deployment.
  • Truenat:
  • Chip-based real-time PCR platform designed for point-of-care testing.
  • Portable, battery-operated, and approved by WHO for TB and rifampicin resistance detection.
  • However, still more expensive than rt-LAMP and requires cold chain for cartridges.

Conclusion

  • The rt-LAMP assay represents a major advancement in the field of TB diagnostics by combining speed, sensitivity, scalability, and affordability.
  • With India's urgent need to accelerate TB elimination, rt-LAMP can significantly enhance early detection and case notification, particularly in resource-limited and high-burden settings.
  • Integration of rt-LAMP into national diagnostic protocols, once validated by ICMR, can strengthen public health infrastructure and reduce TB transmission.

 

Source: https://www.thehindu.com/sci-tech/indigenous-tb-test-can-enhance-accuracy-speed-up-testing/article69439931.ece