Comparison of Different RNA Extraction Methods for Detection of SARS-Cov-2by RT-PCR

ABSTRACT

Background: Corona virus disease 2019 is a highly infectious disease which is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2. SARS-CoV-2 is transmitted from person to person mainly by respiratory droplets and aerosols as well as by direct or indirect contact. Aims and objective: To compare different RNA extraction methods for detection of SARSCov-2 RNA from nasopharyngeal and oropharyngeal swabs using three different methods which are based on different techniques. Material and methods: This analytical observational study was conducted in the department of Microbiology, Sawai Man Singh Medical College Jaipur, Rajasthan from December 2020 to January 2021. We selected 200 confirmed positive (extracted by Easy Mag automated system) (remnant) samples showing a wide range of different Ct values and 20 confirmed negative samples stored in Viral Transport Media VTM for this study. In order to compare quality of three extractions methods, all samples were aliquoted separately for each extraction technique. (1) Extraction by manual method (spin column base) was done by as per manufacturer’s instructions. (2) Extraction by QIA cube HT (vaccum column base) was done by as per manufacturer’s instructions. (3) Extraction by Perkins Elmer chemagic 360 (magnetic beads based). Result: A panel consisting of 200 Covid-19 positive and 20 Covid-19 negative samples were extracted by three methods (i.e. Manual column based, automated column-based and automated magnetic beads-based method). The extracted material/elutes were put for realtime RT-PCR assay for the detection of SARS CoV-2 RNA. There was no major difference seen in individual samples’ ct values between three extraction system. CONCLUSION: In conclusion, we recommended all three RNA extraction methods (i.e. magnetic beads & silica column-based) are interchangeable in a diagnostic workflow for the SARS CoV-2 by RTPCR and can be taken into account for SARS CoV-2 detection in possible future shortage of one kit or times of crisis in such pandemic time.