CRISPR/Cas12a-Assisted Dual Visualized Detection of SARS-CoV-2 on Frozen Shrimps

Given the possibility that food contaminated with SARS-CoV-2 might become an infection source, there is an urgent need for us to develop a rapid and accurate nucleic acid detection method for SARS-CoV-2 in food to ensure food safety. Here, we propose a sensitive, specific, and reliable molecular detection method for SARS-CoV-2. It has a mechanism to control amplicon contamination. Swabs from spiked frozen shrimps were used as detection samples, which were processed by heating at 95 degrees C for 30 s. These preprocessed samples served as the templates for subsequent amplification. A colorimetric LAMP reaction was carried out to amplify both the SARS-CoV-2 target and the MS2 phage simultaneously in one tube. MS2 phage was detected by colorimetric LAMP as the internal control, while SARS-CoV-2 was detected with a CRISPR/Cas12a system. The fluorescence results could be visually detected with an ultraviolet lamp. Meanwhile, uracil was incorporated during the LAMP reaction to provide an amplicon contamination proof mechanism. This test could detect as low as 20 copies of SARS-CoV-2 in one reaction. Additionally, the detection could be finished in 45 min. The test only needs a heating block and an ultraviolet lamp, which shows the potential for field detection.

Automated summary

Given the possibility of SARS-CoV-2 contamination in food, there is an urgent need for a rapid and accurate nucleic acid detection method to ensure food safety. In this study, we propose a sensitive and reliable molecular detection method for SARS-CoV-2. The method includes a control mechanism for amplicon contamination and can detect as low as 20 copies of SARS-CoV-2 in one reaction. The test can be completed in 45 minutes using a heating block and an ultraviolet lamp, making it potentially suitable for field detection.