Coronavirus lab tests set the benchmark for accuracy, and antigen testing is a quick and inexpensive alternative.
But proponents of a third type of test, developed by a Nobel Prize winner using cutting-edge CRISPR technology, say it has the potential to be all three: fast, accurate and inexpensive.
While these gene-editing technology tests are still in development and will not be ready in the United States this year as the weather cools and demand increases, research groups have recently published scientific papers. describing them as an attractive alternative as testing shortages persist in the COVID -19 pandemic.
Dr Jennifer Doudna, a researcher at the University of California at Berkeley whose pioneering work in CRISPR won a share of this year’s Nobel Prize in chemistry, said the test can be performed quickly and does not require a laboratory.
“We have a long way to go before CRISPR-based diagnostics are widely used, but I believe we will see an impact during the current pandemic,” Doudna said. “Because it is simple to tune these assays to detect other targets, the platform we are currently developing sets the stage for deploying CRISPR for rapid diagnosis in future outbreaks.”
CRISPR, or evenly spaced short palindromic repeats, is a gene-editing technology being studied for a wide range of uses, from treatments for cancer and sickle cell disease to improving food production.
In 2016, Doudna’s lab developed a way to detect RNA using this technology. Her lab collaborated with Dr Melanie Ott of the San Francisco-based Gladstone Institutes to develop an HIV test, but when the pandemic struck, researchers focused on developing a test for the coronavirus.
The test recognizes an RNA sequence in SARS-CoV-2, the coronavirus responsible for COVID-19.
In an Oct. 12 post, researchers reported that the test yielded results in five minutes and correctly identified five samples from patients with coronavirus. When used with a mobile phone to detect signals generated by the test, the technology could provide a quick and inexpensive test outside of a lab, the researchers said.in the article, which was not peer reviewed.
Scientists at the Massachusetts Institute of Technology are also refining a CRISPR-based test that can be used outside of a lab. In a letter from the New England Journal of Medicine published last month, researchers said the test was evaluated in a University of Washington lab using 202 samples with coronavirus and 200 without. The test correctly identified 93.1% of the positive samples. The test also had a specificity of 98.5%, meaning it rarely reported false positives.
Feluda, a paper CRISPRtest named after a fictitious Indian detective, has been cleared by that country’s drug regulators for a commercial launch. But it’s unclear how Indian conglomerate Tata Group plans to roll out the test in India, which only trails the United States with nearly 7.7 million cases, according to data from Johns Hopkins University.
Fast and precise tests
Gigi Gronvall, a senior researcher at the Johns Hopkins Center for Health Security, said she expects more labs to explore tests using the technology. She called it “extremely promising” because people can use the tests outside of the lab.
“It’s been a big challenge with testing in general,” said Gronvall. “People need to have their results pretty quickly, otherwise they just go on with their day and they could be contagious and not stop having contact with other people.”
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South San Francisco-based biotechnology company Mammoth Biosciences, co-founded by Doudna, is working to further develop its test and make it available to laboratories and medical providers. The company received a grant from the National Institutes of Health to accelerate its efforts.
Trevor Martin, CEO of Mammoth, said the company’s goal is to test that is both fast and accurate.
“Right now you have to make this choice: do you want something that is simple and fast or something that has the greatest precision?” Said Martin.
The most accurate laboratory tests are the molecular-based polymerase chain reaction, or PCR, which amplifies a small amount of genetic material from a nasal swab sample. Laboratories are limited in the number of PCR tests they can perform due to periodic shortages of chemical reagents and other test materials. In July, when demand exceeded labs’ ability to perform tests, consumers whose tests were routed to major labs routinely waited a week or more for results.
Antigen tests, which detect coronavirus proteins, can produce results in 15 minutes but are considered less sensitive than laboratory tests.
Martin said that the CRISPR-based tests offer “a very simple, very fast, but extremely accurate technology.”
Scale up to be cheap and accessible
Beyond technology, test developers are trying to solve another challenge – designing a test that is easy to use and inexpensive.
Dr Feng Zhang, a biochemist at MIT and a senior fellow at the Broad Institute whose lab is developing the StopCOVID test, said his team wanted to make a low-cost device that could work with a disposable cartridge. The collaborators want a test simple enough that consumers can use it at home by taking their own nasal swab.
“The challenge is figuring out how to increase production so that the cost is as low as possible,” Zhang said.
He said his staff are working to bring the test to market as soon as possible. A version of the test is already being used by a Thai hospital to screen patients.
Martin of Mammoth said that designing a test for wide use is “where a lot of things stumble.”
“It’s really good to have new technology, but you have to get it where it’s needed,” he said. “This is something that we are working on very diligently.”
Dr Sophia L. Yohe, director of the University of Minnesota’s Molecular Diagnostics Lab, said it’s unclear whether test developers will be able to streamline steps to allow for large numbers of tests.
Some early versions of CRISPR tests required the extraction and amplification of samples, similar to laboratory PCR tests, said Yohe, chair of the College of American Pathologists Personalized Health Care Committee.
“If you can only do one test at a time, even if it only takes 30 minutes, suddenly doing a thousand tests takes a long time,” she says. “So I think scalability is an issue that needs to be considered if you plan to do high volumes of testing.”
Ken Alltucker is on Twitter as @kalltucker or can be emailed to [email protected]