Development of a concentration method for simple and sensitive detection of SARS-CoV-2 in saliva using a magnetic nanoparticle kit

Background

When diagnosing viral infections in humans and animals, the presence of virus in a sample in trace amounts that are below the analytical sensitivity of the detection system may cause false negative results and inaccurate diagnosis. We previously reported the development of a simple virion concentration technique using 12 ml large-volume samples that can dramatically improve diagnostic sensitivity by increasing analytical sensitivity by 100-fold over conventional methods. The present study was conducted to further improve the simplicity and versatility of this method. We constructed a simple and highly sensitive method for the detection of SARS-CoV-2 in human saliva after concentration using a magnetic nanoparticle conjugated with polyethylene glycol (PEG).

Results

Performance of the method was evaluated by comparing a combination of automated nucleic acid extraction and RT-qPCR or triplex RT-LAM detection in a spiked sample of 20 ml saliva collected from healthy humans. The method theoretically achieved 300-fold concentration of spiked SARS-CoV-2 in saliva, enabling 10- to 1000-fold higher analytical sensitivity for detection compared to conventional RNA extraction methods.

Conclusions

This newly developed method allows for easy and reliable concentration of the virion in less than 60 min, improving the analytical sensitivity of the SARS-CoV-2 test. Further, the method allows for easy and reliable enrichment of the virus in less than 60 min, improving the analytical sensitivity of the SARS-CoV-2 test. This method is easily used for highly sensitive virus detection from a variety of human oral fluid samples and may also be applied to rapid and labor-saving screening tests by pooling a large number of samples.