New CRISPR-based test for COVID-19 uses a smartphone camera
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Imagine swabbing your nostrils, putting the swab in a device, and getting a read-out on your phone in 15 to 30 minutes that tells you if you are infected with the COVID-19. Now, researchers report a scientific breakthrough that brings them closer to making this vision a reality.

In a new study published in the scientific journal Cell, the team outlined the technology for a CRISPR-based test for COVID-19 that uses a smartphone camera to provide accurate results in under 30 minutes.

Not only can their new diagnostic test generate a positive or negative result, but it also measures the viral load (or the concentration of SARS-CoV-2, the virus that causes COVID-19) in a given sample.

Why this test better than RT-PCR?

Current COVID-19 tests use a method called quantitative PCR -- the gold standard of testing. However, one of the issues with using this technique to test for SARS-CoV-2 is that it requires DNA. Coronavirus is an RNA virus, which means that to use the PCR approach, the viral RNA must first be converted to DNA. In addition, this technique relies on a two-step chemical reaction, including an amplification step to provide enough of the DNA to make it detectable. So, current tests typically need trained users, specialized reagents, and cumbersome lab equipment, which severely limits where testing can occur and causes delays in receiving results.

The novel approach described in this recent study skips all the conversion and amplification steps, using CRISPR to directly detect the viral RNA.

How does it work?

In the new test, the Cas13 protein is combined with a reporter molecule that becomes fluorescent when cut, and then mixed with a patient sample from a nasal swab. The sample is placed in a device that attaches to a smartphone. If the sample contains RNA from SARS-CoV-2, Cas13 will be activated and will cut the reporter molecule, causing the emission of a fluorescent signal. Then, the smartphone camera, essentially converted into a microscope, can detect the fluorescence and report that a swab tested positive for the virus.

Accurate and Quick Results

The device accurately detected a set of positive samples in under 5 minutes. For samples with a low viral load, the device required up to 30 minutes to distinguish it from a negative test.

Source: https://gladstone.org/news/new-crispr-based-test-covid-19-uses-smartphone-camera
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