CRISPR-Based Spit Test Detects SARS-CoV-2 and Variants
Researchers at the Harvard Wyss Institute and MIT have developed an inexpensive at-home test for SARS-CoV-2 and several variants, which does not require nasal swabs. The test uses a simple spit sample, and provides results that can be read using a smartphone app within an hour. With access to a 3D printer and commonly available components, the device can be created for approximately $15, and the researchers hope that it could provide a viable testing option for countries without easy access to centralized laboratories.
While vaccination campaigns have made a dent in the spread of COVID-19 in many countries, the need for testing is as urgent as ever, particularly with the rise of more transmissible variants. Vaccine hesitancy and misinformation have also formed a huge stumbling block in our fight against SARS-CoV-2, meaning that testing will be here for some time to come. While this news is gloomy, the pandemic has had some silver linings, particularly in terms of the scientific response and the acceleration of new technologies, which have been impressive to say the least.
This latest technology is no exception. Emerging from the labs of Harvard and MIT, this low-cost testing device is geared towards regions where access to sophisticated labs is not a given. “miSHERLOCK eliminates the need to transport patient samples to a centralized testing location and greatly simplifies the sample preparation steps, giving patients and doctors a faster, more accurate picture of individual and community health, which is critical during an evolving pandemic,” said Helena de Puig, a researcher involved in the study, via a Wyss Institute announcement.
No one likes inserting a nasopharyngeal swab, and the new test dispenses with this in favor of a simple spit sample. “Simple things that used to be ubiquitous in the hospital, like nasopharyngeal swabs, were suddenly hard to get, so routine sample processing procedures were disrupted, which is a big problem in a pandemic setting,” said Rose Lee, another researcher involved in the study. “Our team’s motivation for this project was to eliminate these bottlenecks and provide accurate diagnostics for COVID-19 with less reliance on global supply chains, and could also accurately detect the variants that were starting to emerge.”
The device relies on CRISPR-based technology called “specific high sensitivity enzymatic reporter unlocking” (SHERLOCK) to cut a gene in SARS-CoV-2 resulting in a fluorescent signal that can be identified using a smartphone app. The researchers have also designed the assay to recognize and identify three variants of the virus (Alpha, Beta and Gamma), but it could be adapted to include the Delta variant in future versions.
“When the miSHERLOCK project started, there was almost no SARS-CoV-2 variant monitoring happening. We knew that variant tracking was going to be incredibly important when evaluating the long-term effects of COVID-19 on local and global communities, so we pushed ourselves to create a truly decentralized, flexible, user-friendly diagnostic platform,” said Jim Collins, a third researcher involved in the project. “By solving the sample prep problem, we’ve ensured that this device is virtually ready for consumers to use as-is, and we’re excited to work with industrial partners to make it commercially available.”
Here’s a video with more about the new testing technology:
Study in journal Science Advances: Minimally instrumented SHERLOCK (miSHERLOCK) for CRISPR-based point-of-care diagnosis of SARS-CoV-2 and emerging variants
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