What is the main goal of our STOPCovid technology?
We believe that the best path for re-opening society and keeping everyone safe is testing, testing, testing. Shortcomings in current testing protocols have limited our ability to expand the essential test-trace-isolate measures that are required to resume normal life. Therefore, we sought to overcome these limitations by creating a COVID-19 test with the following characteristics:
- Rapid: STOPCovid can be performed from start to finish in under 1 hour.
- Sensitive: STOPCovid can detect as little as 100 copies of viral genomic RNA, comparable to standard RT-qPCR methods.
- Simple: No complex skills or laboratory equipment are required to complete a STOPCovid test. It’s as simple as a pregnancy test.
- Low Cost: A STOPCovid can be performed for under $10 per test.
- Scalable: Simple reaction components allow for rapid manufacturing of millions of tests.
Based on previously developed SHERLOCK nucleic acid technology, STOP (SHERLOCK Testing in One Pot) can play a key role in identifying and containing new outbreaks of SARS-CoV-2 on society’s road to recovery.
How easy to use is STOPCovid?
The workflow is very simple and can be run in less than an hour with minimal hands on time as shown above.
How does STOPCovid differ to the SHERLOCK protocol released in February?
The protocol we released in February involves a couple incubation steps, multiple fluid handling steps, and laboratory equipment, limiting use of the protocol to complex labs. The new STOPCovid test is very simple and can be run in less than an hour with minimal hands on time as shown above.
How does STOPCovid work?
- Sample collection: Saliva or nasopharyngeal swab is collected into a reaction tube containing a buffer that breaks open SARS-CoV-2 viral particles, exposing its RNA (nucleic acid) for detection.
- (a). Amplification: Small amounts of viral RNA found in the sample are amplified billions of times over using a method called Loop-mediated Isothermal Amplification (LAMP). Unlike methods employed by the CDC and other PCR-based SARS-CoV-2 tests that require bulky instrumentation, LAMP does not require rapid fluctuations in temperature. (b). CRISPR detection: Amplified viral nucleic acid is recognized by Cas12b, a CRISPR enzyme. Upon recognition, Cas12b cleaves a reporter molecule, breaking a bond between two important molecular features: a FAM molecule and a biotin molecule.
- Sample addition: The amplified and detected sample is added to a lateral flow strip, and begins flowing toward the detection lines.
- Antibody reporter recognition: Antibodies (gold-coated so you can see them) at the bottom of the lateral flow strip bind to the FAM on the reporter molecule as the sample flows up the strip.
- Control line development: If the antibody in step (4) binds an intact reporter molecule, it will get stuck at the first line on the lateral flow strip. At this line is streptavidin, which attaches to the biotin on the reporter. If the biotin was cleaved off the reporter before antibody recognition, the antibody will continue to flow up the strip.
- Testing line development: Any antibody that passes over the control line in step (5) will bind to the test line. At the test line is a molecule that binds any remaining antibody that may have bound to a cleaved reporter.
- Interpreting results: If SARS-CoV-2 nucleic acid is in the sample, the CRISPR enzyme would have broken the bond between the FAM and the biotin on the reporter. Any broken reporter would cause antibodies on the lateral flow strip to bind to the second (test) line instead of the first (control). A band on the test line means the sample was COVID-positive, whereas the absence of a band on the test line means the sample was COVID-negative.
What’s the next step for the technology?
The next steps for STOPCovid are to continue validating the technology on clinical samples through our partners and to begin the process to seek regulatory approval. We will continue to update with new information as we move forward.
What are the different types of testing technologies available?
Common methods for diagnosis of COVID-19 include serology tests for detection of antibodies and RT-qPCR tests for detection of viral RNA genomes. Antibody tests, while portable and inexpensive, are not capable of detecting early disease. RT-qPCR tests are not currently able to be deployed in point of care settings for rapid and scalable diagnostics.
Are there any authorized nucleic acid point of care tests available now?
There are currently three tests, the Abbott ID NOW™ , Cepheid Xpert® Xpress, and Mesa Biotech Accula, authorized for use in point of care settings. However, these tests require specific instrumentation that is not widely available, limiting their current utility.Many other groups are working on rapid point of care nucleic acid tests, and we welcome open sharing of data and collaboration for these point of care tests.
Many other groups are working on rapid point of care nucleic acid tests, and we welcome open sharing of data and collaboration for these point of care tests.
How is STOPCovid different from lateral flow-based antibody serology tests?
Lateral flow serology tests detect the body’s immune response to infection with SARS-CoV-2. As part of this immune response, the body produces antibodies, typically within several days after onset of disease. This delay creates a critical window where a patient can be contagious, but register as COVID-19 negative by these tests, and these tests cannot be used for rapid screening in real-time.
Despite this limitation, these tests are inexpensive to produce and can be run without complex instrumentation, making them a valuable asset in broad detection. Furthermore, they can detect whether a patient was infected at a point in the past.
How is STOPCovid different from RT-PCR based diagnostics?
RT-PCR requires complex instrumentation required to rapidly change temperature (thermocycle) and accurately measure changes in absorbance and emission of light from a specific wavelength (fluorescence). STOPCovid’s underlying technology doesn’t require thermocycling or fluorescence, allowing a much simpler device (or even no device) to be used.
How is point-of-care testing relevant for re-opening society?
Point of care (POC) testing that can be done in low resource settings or at home is needed to inform whether new outbreaks are occurring and to clear people for going to work or socializing in public spaces. Lab based tests are too centralized and not rapid enough to be used in such a manner to allow people to make real-time decisions about whether to go outside or go to work. As nucleic acid based testing is the only type of test that can diagnose active infection in a highly sensitive manner (see above), we must develop and distribute nucleic acid based POC tests.
What will the cost be?
While the cost of goods for each test is low, we do not know the final cost of what this test would be in practice. We are actively working to keep the cost of the test under $10 for the user.
How do I get a kit?
Right now kits are only available to scientific or clinical collaborators. These research use only (RUO) kits can be requested using our application form. Because our test is not clinically validated or authorized by the FDA, we cannot distribute kits to the general public. We are actively engaging with regulators to bring this test to the public.
How accurate is the test?
STOPCovid has sensitivity similar to other POC tests approved under Emergency Use Authorization (EUA) shown here. Further clinical validation is required to accurately determine key performance metrics, but initial testing on a small patient cohort revealed that STOPCovid achieves 97% sensitivity and 100% specificity. We are continuing to test more samples through our clinical collaborator network and will update these metrics as we receive more data.