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Co-Diagnostics Presents Rapid Diagnostic Test For Coronavirus In San Francisco

By Allison Proffitt

March 4, 2020 | Co-Diagnostics presented their new rapid diagnostic test for COVID-19 yesterday at the Molecular Medicine TriConference in San Francisco. The Salt Lake City, Utah, diagnostics company is among the many companies working on a rapid diagnostic test for COVID-19.

Co-Diagnostics was founded in 2013 to make affordable, accurate, user-friendly real-time PCR tests for infectious disease, agriculture, cancer research, and mosquito-borne illnesses. The company’s Logix Smart family of tests are real-time RT-PCR tests that use the company’s patented CoPrimer technology to detect the presence of RNA specific to the virus in question and avoid nonspecific amplification problems. The company makes Logix Smart tests for West Nile virus, Zika virus, dengue, chikungunya, Western equine encephalitis, tuberculosis and other diseases.

In the case of the 2019-nCoV virus, Co-Diagnostics researchers began working on a diagnostic test when the World Health Organization released a diagnostic protocol  on January 17, 2020, said Masen Christsensen, senior design engineer at Co-Diagnostics. The company chose an RNA-dependent RNA polymerase (RdRp) gene and the E gene for early test design. Since then the company has focused on the RdRp marker because it shows least cross-reactivity with other species.

“The RdRp marker is looking great as far as specificity and sensitivity to the COVID-19 marker,” Christsensen said.

Christsensen explained how the CoPrimer system works. The company creates an extremely short, low melting temperature (between 5-20 degrees below the annealing temperature) primer. Such a primer would not generally be successful at binding to its target, so the company tethers it to a capture sequence, connected by a flexible polyethylene glycol leash.

“When that capture sequence binds, the primer is in artificially close proximity to its target sequence, which increases the local concentration of the primer by approximately 10,000 times,” Christsensen explained. The capture sequence and the flexible leash are cleaved, and the primer is able to consistently bind and the polymerase amplifies.

The system allows for massive multiplexing without issues of nonspecific amplification, cross-reactivity between primers, or primer-dimer issues, Christsensen told the audience. “We are able to engage in SNP differentiation at much higher efficiency than traditional primers, because this primer is so sensitive to single-nucleotide mismatches with it already being so short in the first place,” he continued. And because both the probe and the primer must bind, the system avoids cross-reactivity with closely-related species.

Co-Diagnostics has been using sequence information for the 2019-nCoV virus available on the NCBI nucleotide sequence database. “Huge thanks to those who put together public databases, otherwise the field of molecular diagnostics would be much harder!” Christsensen said.

The company remains focused on the RdRp gene instead of the nucleocapsid (N) gene that the CDC diagnostic uses, “because the resulting test can be used as a companion, as a confirmatory, or independent to the CDC test, so it’s not redundant. It just targets a different area of the genome,” Christsensen explained.

Thus far, the company’s CoPrimer regions are completely conserved across 2019-nCoV virus sequences and are differentiated from SARS and MERS viruses. “We continue to monitor as new sequences are added to the database to make sure that we are remaining as full sensitivity and fully able to detect every strain of [the] COVID-19 [virus],” Christsensen said.

The test takes about an hour from blood sample collection to results, Christsensen said. (Company literature says that the assay runtime takes less than 90 minutes and analysis less than 10 minutes.) The company has priced the kits at $7.00 per reaction. A 100-reaction kit costs $700 and a 250 reaction kit costs $1750. Test kits include LogixSmart CoPrimer MasterMix, internal positive control, and nuclease free water.

US Sales Launched Saturday

The Co-Diagnostics test became commercially available in the US on Saturday. On February 29, FDA issued guidance for diagnostics testing in labs certified to perform high complexity testing under CLIA prior to Emergency Use Authorization for Coronavirus Disease-2019 during the public health emergency. The immediately-effective guidance states that, “circumstances exist justifying the authorization of emergency use of in vitro diagnostics for detection and/or diagnosis of the novel coronavirus (2019-nCoV). Rapid detection of COVID-19 cases in the United States requires wide availability of diagnostic testing to control the emergence of this rapidly spreading, severe illness. This guidance describes an accelerated policy enabling laboratories to use tests they develop faster in order to achieve more rapid testing capacity in the United States.”

Dwight Egan, CEO of Co-Diagnostics, said the FDA guidance shuts down the typical laboratory developed test (LDT) route, but opened up the market in the US for the sale of Logix Smart COVID-19 to CLIA-certified labs. Those labs can order tests and begin their own validation, submitting their application for emergency use authorization, and immediately using the tests.

“Over the weekend the FDA of the United States open up the availability of the utilization of tests such as ours to be used by CLIA laboratories in the United States as part of their FDA submission for emergency use authorization. So they just opened it up widely for us to solve that problem,” he told the Molecular Medicine TriConference audience. “Most of our shipments to date have been worldwide; we have not been able to sell it in the United States until Saturday morning. But with the new directive from the FDA we have been able to now contact CLIA labs that still have to comply appropriately with the FDA submissions for Emergency Use, but that should facilitate greatly the ability for testing to be done in the United States.”

Co-Diagnostics started shipping Logix Smart COVID-19 tests about 10 days to two weeks ago, Egan told Diagnostics World. The company’s facility in Salt Lake City can produce 50,000 test kits per day, he said, and has a relationship with a facility in India that has a capacity of 100,000 kits per day. Egan wouldn’t share the number of kits already shipped, but said the number is “not insubstantial.”

His hope is that labs across the country will use the Co-Diagnostics test as a validator for the existing CDC test because the two measure different markers of the virus.

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