Hyderabad

CSIR-CCMB’s dry swab RT-PCR test method gets more validation

CSIR-CCMB’s novel ‘Dry Swab’, extraction-free direct RT-PCR testing method, which has reduced the time taken for the COVID test result to be declared, got further validation with another study highlighting the ‘immense’ value of the method in the detection of any kind of variant, better sensitivity and illuminating more ‘scientific dimensions’.

Published by the Indian Academy of Sciences, Journal of Biosciences, in the latest issue, the “Temporal Stability and Detection Sensitivity of Dry Swab Diagnosis” of SARS-CoV-2 by scientists C.G. Gokulan, Uday Kiran, Santosh Kumar K and Rakesh Mishra of CSIR-CCM, Academy of Scientific and Innovative Research (AcSIR), Ghaziabad and Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt (Germany), discussed more advantages and scope for commercialisation as it can increase lab throughput by three-folds.

Challenges like reagent shortage, limited human resources and high transmission rate can be handled in a better manner to contain the infection and better allocation of medical resources, as it can quickly diagnose and control the spread. The study on temporal stability of two strains of SARS-CoV-2 at two different temperatures indicates that for shorter distance transportation, cold chain can be avoided and the dry swab samples with low viral load also is stable at RT for 24 hours.

In case of high sample surge, the swabs can be stored at 4°C for up to 3 days without compromising the detection sensitivity. The method is expected to hold similar advantages in case of other emerging variants of SARS-CoV-2 as indicated by multiple sewage surveillance and sequencing studies, it said.

This suggests that while the virus variants could be different with respect to the rate of infection and eliciting immune response, they are generally stable for longer time in different conditions. Throughput of dry swab-based sample processing could be further increased by collection of samples directly into tubes containing the ‘TE-P buffer’ and since no transportation is required, it would increase the turnover time drastically when thousands of samples are being tested.

“There is no loss of detection seen upon storage at RT for up to 3 or 4 days of time and results indicated that a minimum final concentration of 0.5 mg/ml of proteinase K is enough to produce results comparable to that of 2 mg/ml,” they said. This suggests tests can be increased four times and corresponding costs reduced.

Data indicates that dry swab method correlates well with the conventional method. Lesser CT values of dry swab samples in comparison to that of the VTM-RNA samples suggest better sensitivity of the method within 48 hours of time. Dry swab samples are also found to be stable at RT for 24 hours and the detection of SARS-CoV-2 RNA by RT-PCR do not show variance from VTM-RNA.

This extraction free, direct RT-PCR method holds phenomenal standing in the present life-threatening circumstances due to COVID. Thus, we propose dry swab method as a viable and economical alternative for the existing gold standard https://rdcu.be/cAJ7Q, they added.


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Printable version | Apr 30, 2022 9:42:34 pm | https://www.thehindu.com/news/cities/Hyderabad/csir-ccmbs-dry-swab-rt-pcr-test-method-gets-more-validation/article37368123.ece