Integrated sample inactivation, amplification, and Cas13-based detection of SARS-CoV-2
diagnostics molecular biology
Authors: Jon Arizti-Sanz et al
Journal/ Pre-Print: biorxchiv
Key Words: Cas13a SHINE
1. Single-step detection of SASR-CoV-2 RNA with LOD 10cp/µL using fluorescence as read-out (named SHERLOCK)
2. App that uses camera of mobile phone to interpret the fluorescence read-out
3. SHERLOCK reaction optimized to detect SARS-CoV-2 RNA extracted with Heating Unextracted Diagnostic Samples to Obliterate Nucleases (HUDSON).
The authors have optimized a Cas13-based detection method for SARS-CoV-2 RNA extracted by Heating Unextracted Diagnostic Samples to Obliterate Nucleases (HUDSON) from patient saliva and nasopharyngeal swabs. Limit of detection is 10 copies (cp)/µL when using fluorescence as read-out (comparable sensitivity to RT-PCR), that can be combined with an app that provides a binary result using a picture of the tube taken with a mobile phone camera.
Impact for SARS-CoV2/COVID19 research efforts
Develop diagnostic tools for SARS-CoV2/COVID19
· In vitro study
Strengths and limitations of the paper
Novelty: Optimized for RNA extracted with HUDSON along with the app to capture the result, and generates a novel dataset.
Standing in the field: LOD of 10cp/µL is the required level of detection. Multiple Cas-based tests have been developed, but this one is optimized for use with HUDSON RNA extracts.
Appropriate statistics: yes
Viral model used: SARS-CoV-2 viral seedstocks (no reference)
Translatability: Ready to be used in the field
Main limitations: Not a novel method, simply an optimized version of SHERLOCK and HUDSON.
Although the developed method is faster and does not require specialized lab equipment, the sensitivity is slightly less that RT-PCR when comparing in NP swabs.
Authors refer to Fig 2I in text, but that fig does not exist.