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Covid-19 Test based on CRISPR Instead of RT-PCR

The new Test for COVID-19 detection based on CRISPR Technology  confirms presence of viral DNA in samples faster and more accurately  than the RT-PCR based test kits used globally as of now.Sherlock Biosciences’s CRISPR SARS-CoV-2 Rapid Diagnostic kit with the detection time of 1 hour receives FDA Emergency Use Authorization in the United States

A new kit — based on clustered regularly interspaced short palindromic repeats (CRISPR) technology — that tests for the novel coronavirus (SARS-CoV-2) in an hour’s time and the results for which can be seen through the naked eye, is now available.

  1. The diagnostic kit received Emergency Use Authorisation by the United States’ Food and Drug Administration on May 7, 2020.
  2. The Kit has been developed by biotechnology firm Sherlock Biosciences.The Sherlock CRISPR SARS-CoV-2 kit is based on the CRISPR-based SHERLOCK (Specific High Sensitivity Enzymatic Reporter UnLOCKing) technique.
  3. It does not give false negative or false positive results and has high sensitivity and specificity, unlike Reverse Transcription Polymerase Chain Reaction (RT-PCR) and immunoassays tests.
  4. The genetic material from the Ribonucleic acid (RNA) of the virus does not need to be converted to Deoxyribonucleic acid (DNA), unlike RT-PCR based tests.
  5. This is the first time a CRISPR-based tool has been used as a diagnostic.
  6. The technology for the kit was developed by a team led by CRISPR pioneer Feng Zhang at the Eli and Edythe L Broad Institute operated by the Massachusetts Institute of Technology and Harvard University at Cambridge, Massachusetts and marketed by Sherlock.

STEPS of the CRISPR based Test :

The test for COVID-19 based on CRISPR technology  has three steps. Genetic material is extracted from the patients’ sample and is amplified using a commercially available polymerase amplification kit. This step takes around 25 minutes.

The amplified viral sample is then incubated with and detected with Cas13 (an RNA editing technique), which takes 30 minutes.

A commercially available paper dipstick is then used to confirm the presence of the virus. This confirmation can be done through the naked eye and takes around two minutes.

The test based on CRISPR for Covid-19 only needs basic equipment found in most labs.

In addition to SHERLOCK, the company is also developing its INSPECTR™ platform to create an instrument-free, handheld test – similar to that of an at-home pregnancy test – that utilizes Sherlock Biosciences’ Synthetic Biology platform to provide rapid detection of a genetic match of the SARS-CoV-2 virus.

What is CRISPR-Cas9 Technology?

CRISPR-Cas9, which is short for clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9, is a genome editing technology.

Genome editing (also called gene editing) is a group of technologies that give scientists the ability to change an organism’s DNA. These technologies allow genetic material to be added, removed, or altered at particular locations in the genome

  • CRISPR-Cas9 was adapted from a naturally occurring genome editing system in bacteria.
  • The bacteria capture snippets of DNA from invading viruses and use them to create DNA segments known as CRISPR arrays.
  • The CRISPR arrays allow the bacteria to “remember” the viruses (or closely related ones). If the viruses attack again, the bacteria produce RNA segments from the CRISPR arrays to target the viruses’ DNA.
  • The bacteria then use Cas9 or a similar enzyme to cut the DNA apart, which disables the virus.
  • The CRISPR-Cas9 system works similarly in the lab. Researchers create a small piece of RNA with a short “guide” sequence that attaches (binds) to a specific target sequence of DNA in a genome. The RNA also binds to the Cas9 enzyme. As in bacteria, the modified RNA is used to recognize the DNA sequence, and the Cas9 enzyme cuts the DNA at the targeted location. Although Cas9 is the enzyme that is used most often, other enzymes (for example Cpf1) can also be used. Once the DNA is cut, researchers use the cell’s own DNA repair machinery to add or delete pieces of genetic material, or to make changes to the DNA by replacing an existing segment with a customized DNA sequence

The medical applications of CRISPR have taken the spotlight, especially after the intense criticism that surged after a Chinese scientist revealed to the world the birth of ‘CRISPR twins’, the first humans to be born from a gene-edited embryo.

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Source-Down To Earth

 

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