RNA extraction-free CRISPR-based SARS-CoV-2 detection in viral transport medium and dry swab-a comparative analysis:...

CRISPR-Cas-based methods have shown high efficacy in detecting SARS-CoV-2. Amidst the Covid-19 pandemic, numerous studies have explored SARS-CoV-2 detection methods without the need for RNA extraction, aiming to reduce cost and processing time. Here, we assessed a CRISPR-based SARS-CoV-2 detection method's ability to detect the virus in viral transport medium (VTM). Swabs obtained from Covid-19 positive patients and stored in two Indian brands of VTM were examined alongside dry swab samples. The samples underwent proteinase -K treatment followed by heat incubation. The released nucleic acids were tested by RT-LAMP and CRISPR-based detection. We conclude that SARS-CoV-2 can be detected in VTM of two commercial preparations as well as dry swab samples without RNA extraction and purification. COVID detection was found to be more efficient for dry swab samples compared to VTM samples. The work flow described in this paper can be extended to other respiratory diseases.