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Sunday, October 11, 2020
The coronavirus is still detected in complex PCR tests. But researchers are now developing a test that is faster and cheaper. The Crispr gene scissors are used here; this year’s Nobel Prize winner also participates.
American researchers have developed a rapid test for the detection of Sars-CoV-2, which is based on the Crispr gene scissors. In a study that had not yet been peer-reviewed, the team led by Daniel Fletcher of the University of Berkeley and Melanie Ott of the Gladstone Institute managed to obtain a test result in a few minutes. With only five samples examined, the data situation is still scarce.
The method uses a short RNA molecule to find a virus gene that is unique to Sars-Cov-2. This guide RNA (crRNA) accumulates there. The virus gene is then cut out with the gene scissors itself, the Cas13 enzyme. At the same time, a reporter RNA carrying a fluorescent marker is released. This is made to shine with a laser. The released fluorescent particles can be captured with a camera. The more intense the fluorescence, the greater the number of viruses it contains.
The researchers carried out their tests with three different types of guide RNA. The virus gene was cut in several places with the Cas13 enzyme. In a longer series of experiments, they were finally able to find the most suitable combination; the sensitivity in particular varied depending on the crRNA. If the figures in the publication are confirmed, the test could detect very small amounts of 100 copies of virus per microliter.
Fast and cheap
This is less accurate than current gold standard PCR tests. However, they are time consuming, require special equipment, and take several hours to complete. Therefore, they can only be performed in laboratories.
However, according to the researchers, the new type of Crispr test only needs a small screening device that could be available in doctors’ offices or even private homes. The color reaction was recorded with a standard smartphone. According to the researchers, their test not only detects if the virus is present, but also measures how high the viral load is. This information could help doctors make treatment decisions based on each patient’s condition, said molecular biologist Max Wilson of the “journal Science” in an initial evaluation.
More studies will now investigate whether the test is really suitable for clinical use. The research team that developed the test also includes Jennifer Doudna, who, along with Emmanuelle Charpentier, received the Nobel Prize in Chemistry this year for discovering the Crispr method.
