WASHINGTON: Scientists have developed novel technology for a CRISPR-based Covid-19 diagnostic test that uses a smartphone camera to provide accurate results in less than 30 minutes.
According to research published in the journal Cell, the new diagnostic test can not only generate a positive or negative result, it also measures the viral load – the concentration of virus – in a given sample.
All CRISPR diagnostics to date have required viral RNA to be converted to DNA and amplified before it can be detected, adding time and complexity, the researchers said.
In contrast, the new approach skips all the conversion and amplification steps, using CRISPR to directly detect viral RNA, they said.
“One of the reasons we are excited about CRISPR-based diagnostics is the ability to get fast and accurate results where they are needed,” said Jennifer Doudna, principal investigator at the Gladstone Institutes in the US.
“This is especially useful in places with limited access to testing, or when rapid and frequent testing is needed. It could eliminate many of the bottlenecks that we have seen with Covid-19,” Doudna said.
Doudna won the 2020 Nobel Prize in Chemistry for co-discovering CRISPR-Cas genome editing, the technology behind this work.
In the new test, the Cas13 protein is combined with a reporter molecule that turns fluorescent when cut and then mixed with a patient sample from a nasal swab, the researchers said.
The sample is placed in a device that connects to a smartphone. If the sample contains SARS-CoV-2 RNA, Cas13 will become activated and cut the reporter molecule, causing the emission of a fluorescent signal, they said.
The smartphone camera, essentially turned into a microscope, can detect fluorescence and report that a swab tested positive for the virus, according to the researchers.
They say the trial could be adapted to a variety of mobile phones, making the technology easily accessible.
When the scientists tested their device on patient samples, they confirmed that it could provide a very fast turnaround time of results for samples with clinically relevant viral loads.
The research found that the device accurately detected a set of positive samples in less than 5 minutes.
For samples with a low viral load, the researchers said, the device required up to 30 minutes to distinguish it from a negative test.
According to research published in the journal Cell, the new diagnostic test can not only generate a positive or negative result, it also measures the viral load – the concentration of virus – in a given sample.
All CRISPR diagnostics to date have required viral RNA to be converted to DNA and amplified before it can be detected, adding time and complexity, the researchers said.
In contrast, the new approach skips all the conversion and amplification steps, using CRISPR to directly detect viral RNA, they said.
“One of the reasons we are excited about CRISPR-based diagnostics is the ability to get fast and accurate results where they are needed,” said Jennifer Doudna, principal investigator at the Gladstone Institutes in the US.
“This is especially useful in places with limited access to testing, or when rapid and frequent testing is needed. It could eliminate many of the bottlenecks that we have seen with Covid-19,” Doudna said.
Doudna won the 2020 Nobel Prize in Chemistry for co-discovering CRISPR-Cas genome editing, the technology behind this work.
In the new test, the Cas13 protein is combined with a reporter molecule that turns fluorescent when cut and then mixed with a patient sample from a nasal swab, the researchers said.
The sample is placed in a device that connects to a smartphone. If the sample contains SARS-CoV-2 RNA, Cas13 will become activated and cut the reporter molecule, causing the emission of a fluorescent signal, they said.
The smartphone camera, essentially turned into a microscope, can detect fluorescence and report that a swab tested positive for the virus, according to the researchers.
They say the trial could be adapted to a variety of mobile phones, making the technology easily accessible.
When the scientists tested their device on patient samples, they confirmed that it could provide a very fast turnaround time of results for samples with clinically relevant viral loads.
The research found that the device accurately detected a set of positive samples in less than 5 minutes.
For samples with a low viral load, the researchers said, the device required up to 30 minutes to distinguish it from a negative test.
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