Development of a simple and highly sensitive virion concentration method to detect SARS-CoV-2 in saliva

Background

Controlling novel coronavirus pandemic infection (COVID-19) is a global challenge, and highly sensitive testing is essential for effective control. The saliva is a promising sample for high-sensitivity testing because it is easier to collect than nasopharyngeal swab samples and allows large-volume testing.

Results

We developed a simple SARS-CoV-2 concentration method from saliva samples that can be completed in less than 60 min. We performed a spike test using 12 ml of saliva samples obtained from healthy volunteer people, and the developed method performance was evaluated by comparison using a combination of automatic nucleic acid extraction followed by RT-qPCR detection. In saliva spike tests using a 10-fold dilution series of SARS-CoV-2, the developed method was consistently 100-fold more sensitive than the conventional method.

Conclusions

The developed method can improve the sensitivity of the SARS-CoV-2 test using saliva and speed up and save labor in screening tests by pooling many samples. Furthermore, the developed method has the potential to contribute to the highly sensitive detection of various human and animal viral pathogens from the saliva and various clinical samples.

Highlight

• A method has been developed to detect SARS-CoV-2 from human saliva with 100 times higher sensitivity than conventional methods.

• The developed method combines simple pretreatment within 60 min with conventional nucleic acid extraction and RT-qPCR.

• This method can be applied for more sensitive virus testing from individual saliva.

• This method can potentially be applied to screening more than 100 saliva samples while maintaining the equivalent detection power of conventional methods.

• The method can be adapted to improve the sensitivity of detecting various pathogens from human and animal saliva.