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Review 2: "Development of a Simple and Highly Sensitive Virion Concentration Method to Detect SARS-CoV-2 in Saliva"

The reviewers found the hypothesis to be sound and the data reliable. However, they raised concerns about the practicality of using 12ml saliva samples, which is a large volume and not attainable for many patients.

Published onJun 06, 2024
Review 2: "Development of a Simple and Highly Sensitive Virion Concentration Method to Detect SARS-CoV-2 in Saliva"
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key-enterThis Pub is a Review of
Development of a simple and highly sensitive virion concentration method to detect SARS-CoV-2 in saliva
Development of a simple and highly sensitive virion concentration method to detect SARS-CoV-2 in saliva

Abstract 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.

RR:C19 Evidence Scale rating by reviewer:

  • Potentially informative. The main claims made are not strongly justified by the methods and data, but may yield some insight. The results and conclusions of the study may resemble those from the hypothetical ideal study, but there is substantial room for doubt. Decision-makers should consider this evidence only with a thorough understanding of its weaknesses, alongside other evidence and theory. Decision-makers should not consider this actionable, unless the weaknesses are clearly understood and there is other theory and evidence to further support it.


Review: The article quickly goes over a pre-purification technique for saliva samples. It is well-written, and the data is fine but incomplete.

Issues to be addressed:

  • Overall, there is very little data, only one experiment and there appear to be no replicates.  Can they show what impact different amounts of time or concentrations make on the output for example?

  • The 'standard method' listed is somewhat artificial since many articles have come out in the last four years that have provided ways to concentrate and get better sensitivity for these exact tests.  It would be important to compare to a modern state-of-the-art method, rather than to a completely vanilla prep

  • It appears that the authors are comparing a large volume input (12ml) to their new method to a small volume (50uL) input to the "standard" method. This could be trying to test the idea of pooling multiple samples, but it is still better to compare the methods in a more direct way with identical input

  • Data Figures should be included that, perhaps, show the full raw data, such as the amplification curves.  Only including the summary data as tables doesn't allow the data to be evaluated by the readers

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