A simple method for SARS-CoV-2 detection by rRT-PCR without the use of a commercial RNA extraction kit

Abstract

The World Health Organization (WHO) has declared a pandemic caused by a new coronavirus named SARS-CoV-2. The growing demand for commercial kits used for automated extraction of SARS-CoV-2 RNA, a key step before rRT-PCR diagnosis, could cause a shortage of stocks that hinders the rapid processing of samples. Although the recommendation is to use automated methods for nucleic acid extraction, alternatives are necessary to replace commercial kits. However, these alternatives should be as reliable as automated methods. This work describes a simple method to detect SARS-CoV-2 from specimens collected in different preservation media. Samples were previously inactivated by heating and precipitating with a PEG/NaCl solution before rRT-PCR assays for Orf1ab, N and S genes. The new method was compared with an automated protocol of nucleic acid extraction. Both procedures showed similar analytical results. Consequently, this simple and inexpensive method is a suitable procedure for laboratory diagnosis of SARS-CoV-2 infection.

Keywords: COVID-19; PEG/NaCl; Precipitation; RNA extraction; SARS-CoV-2; rRT-PCR.

Conflict of interest statement

The authors declare that there are no conflicts of interest associated with this work.

Copyright © 2020 Elsevier B.V. All rights reserved.

Figures

Fig. 1

Comparison of average Ct values between easyMAG® extraction and PEG/NaCl precipitation for A. Orf1ab gene, B. N gene and C. S gene (*p < 0.0001, Wilcoxon test). The line inside the box plot represents the median and the box extends from lower to upper quartiles. Whiskers indicate the 90th and 10th percentiles and dots represent outliers. Mean is shown as “+”.

Fig. 2

Comparison of average Ct values for Orf1ab, N and S genes within easyMAG® extraction and PEG/NaCl precipitation (*=p