PREreview of Development and Evaluation of A CRISPR-based Diagnostic For 2019-novel Coronavirus

Tatiana Hillman

PLOS

5/10/20

Development and Evaluation of A CRISPR-based Diagnostic 2 For 2019-novel Coronavirus

(Hou et al., 2020)

PLOS Discussion:

The CRISPR-nCoV assay is convenient and greatly needed in the laboratory and in the

clinical setting. Because the CRISPR-nCoV assay does not require thermal cyclers, the time of the testing is decreased, and this assay can operate in a setting with minimal resources.

Presently, there is a demand for more testing of the 2019-nCoV virus. In some states and

counties testing is limited. Also, the current tests take a long time to produce results. The

fastidious and rapid diagnosis of 2019-nCoV may help many quarantine earlier before the

symptoms become too intense. The CRISPR-nCoV is exceptional because less instruments as thermal cyclers are required, which could help transfer the CRISPR-nCoV into the clinical setting. However, mNGS, a metagenomic test, is still needed to track any signs of genetic drift in the 2019-nCoV viral genome.

CRISPR detection of 2019-nCoV is an extremely promising assay with much potential

because it can provide tests with high sensitivity and specificity. The inclusion of CRISPR

technology increases and produces test results for 2019-nCoV with higher specificity because

Cas13a can directly target and cleave RNA, using crRNA as guide RNAs. The 2019-nCoV is a

single strand RNA virus, so the synthesized guide RNAs can bind to and guide the Cas13a

nuclease to that specific RNA sequence for cleavage.The CRISPR-nCoV assay detected RNA sequences of 2019-nCoV, fluorescent signals were produced, and then collected. The

sensitivity of CRISPR detection for 2019-nCoV was extremely sensitive during serial dilutions at many different nucleic acid concentrations.

The results of the sensitivity tests determined that 7.5 copies of 2019-nCoV were

detected in all 10 replicates, 2.5 copies were found in 6 out of 10 replicates, and 1.25 copies were in 2 out of 10 replicates (Hou et al., 2020). Specificity tests for CRISPR-nCoV were tested against DNA from human cells, microbes, human coronaviruses, and other respiratory viruses where nonetriggered false positive results. From ROC analysis 100% sensitivity and specificity results of the curves were produced from the positive 2019-nCoV test results. The ROC results are important for use of CRISPR-nCoV in the clinical setting where highly sensitive and specific tests are required. No false positives were detected from all 62 cases. Transferring the CRISPR-nCoV tests to the clinical setting has much promise and potential.

References

Hou T, Zeng W, Yang M, Chen W, Ren L, Ai J, Wu J, Liao Y, Gou X, Li Y, Wang X. Development and Evaluation of A CRISPR-based Diagnostic For 2019-novel Coronavirus. medRxiv. 2020 Jan 1.