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Development of an accurate and rapid diagnostic method for COVID-19 using CRISPR-Cas3
―Paper test strip results are possible within 40 minutes―

Development of an accurate and rapid diagnostic method for COVID-19 using CRISPR-Cas3―Paper test strip results are possible within 40 minutes―.

medRxiv on June 2, 2020. DOI:10.1101/2020.06.02.20119875
 
Kazuto Yoshimi, Kohei Takeshita, Seiya Yamayoshi, Satomi Shibumura, Yuko Yamauchi, Masaki Yamamoto, Hiroshi Yotsuyanagi, Yoshihiro Kawaoka, Tomoji Mashimo
“Rapid and accurate detection of novel coronavirus SARS-CoV-2 using CRISPR-Cas3”
URL: https://www.medrxiv.org/content/10.1101/2020.06.02.20119875v1
A new diagnostic method for COVID-19, SARS-CoV-2, using the Japanese genome editing technology CRISPR-Cas3 (*1) has been developed that can accurately detect COVID-19 in 40 minutes. A research team working in The Institute of Medical Science, The University of Tokyo, published their method on the pre-print server medRxiv on June 2.

The new diagnostic method, named "CONAN (*2)," was the first to use CRISPR-Cas3 to detect the new coronavirus (SARS-CoV-2). The test is performed using a nasopharyngeal swab to detect viral RNA.

CRISPR-Cas3 is a genome editing tool developed in Japan that artificially cuts DNA via a multiprotein complex. It was developed in 2019 by the research team leader, Professor Tomoji Mashimo, The Institute of Medical Science, The University of Tokyo and other researchers.

CRISPR-Cas-3 is a Class 1 CRISPR system that can be programmed to target a defined gene sequence. The team used this mechanism to detect trace amounts of viral RNA found in genomic samples of patients infected with SARS-CoV-2. 

The research team found a positive concordance rate (PPA) of 90% (9/10 cases) and a negative concordance rate (NPA) of 95.3% (20/21 cases), which rivals the PCR test method in detection sensitivity and specificity. In addition, the team claimed success in detecting the presence or absence of viral RNA down to the tens-of-copies level with a test strip in only 40 minutes.
Please see the medRxiv for more details. 

(*1) CRISPR-Cas3
Many bacteria have a defense system called "CRISPR-Cas system" that resembles adaptive immunity. CRISPR-Cas3 is a CRISPR system belonging to Class 1 among CRISPR systems of bacteria and archaea. It was developed in 2019 as a domestic genome editing tool that artificially cuts DNA with a multiprotein complex.

(*2) CONAN
Cas3 Operated Nucleic Acid detectioN method. By using a mixture of CRISPR-Cas3 protein that recognizes the target sequence and a DNA probe for detection as a biosensor, it is possible to detect quickly and accurately whether or not the target sequence is present in a sample.
 

Figure: Rapid diagnostic tests against infectious diseases
 
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