Chennai: Scientists at the Centre for Cellular and Molecular Biology (CCMB), Hyderabad, have found that about 50 per cent of Covid-19 positive samples tested through the standard RT-qPCR test may not yield the correct result.
The researchers found a high percentage of false negative cases while comparing the RT-qPCR with a new test method developed by the them.
CCMB has developed a new low-cost and low-tech required test for SARS-CoV-2 testing known as reverse transcription nested PCR (RT-nPCR) test.
This test does not require real-time quantitative RT-qPCR. The RT-nPCR developed by the CCMB research team has shown comparable performance to the standard RT-qPCR test. The nested PCR (RT-nPCR) approach does not depend on RT-qPCR but uses standard RT-PCR as part of an endpoint assay.
Rakesh Mishra, Director, CCMB, said, “We developed and tested an RT-nPCR protocol comprising a multiplex primary RT-PCR for amplification of four SARS-CoV-2 amplicons and a control human amplicon followed by a secondary nested PCR for individual amplicons. We also examined the use of RT-nPCR in pooled testing and in direct amplification without RNA isolation.”