Small Tweaks, Big gains: Development of Dry Swab Testing for SARS-CoV-2 Diagnosis

Published on 25 March 2023 at 23:17

COVID-19 pandemic presented an unprecedented challenge to humanity, and the governments and health agencies had to quickly devise strategies to control the disease spread. Screening people for the virus was a key step in preventing its spread, but in a populous country like India, this required technical expertise and facilities. 

The Center for Cellular and Molecular Biology (CCMB), a research institute equipped with world-class instruments, took up the responsibility to fight against COVID-19 by becoming a testing centre. The testing process involved collecting samples from patients in liquid Viral Transport Media (VTM), cataloging them with a unique CCMB code, and isolating RNA for setting up RT-qPCR to detect the viral RNA. However, the RNA isolation step was found to be a major bottleneck in the testing procedure.

To address this, the CCMB team worked on a protocol that eliminated the RNA isolation step, saving both time and cost. The protocol used a readily available and inexpensive elution buffer called Tris-EDTA (TE) buffer to extract the nucleic acid from the swab sample. The RT-qPCR results of the samples prepared by direct TE-extract were found to be comparable to RNA isolated from VTM, the gold standard method.

This method made the testing process two times faster and less expensive than the conventional method, while also minimizing the time and consumables required for packing and unpacking the samples, the risk of contamination, and the infection of the sample handling staff. Additionally, this method helped mitigate the problem of false negatives in diagnosis, which was a growing concern in contemporary studies.

The CCMB team's work has been summarized and posted on a preprint server bioRχiv, later published in Biology Methods and Protocols Journal , Oxford Academic, and a proposal for implementation of this methodology was approved by the Indian Council of Medical Research (ICMR). only possible due to the support of the entire COVID-19 Fighting Force of CCMB, who are working tirelessly to overcome the pandemic. The CCMB culture of encouraging and research-oriented atmosphere was instrumental in making this research possible.

Team: Uday Kiran, C G Gokulan, Santosh Kumar Kuncha, Rakesh K Mishra

Written by CG Gokulan, Uday Kiran and Santosh Kuncha

original article published in CCMB COVID Chronicles

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