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Immunoassays for Coronavirus Testing, Including Self-Tests, Targeted by Mologic

NEW YORK – The bulk of diagnostic testing for SARS-CoV-2 is done by laboratory-based molecular methods, but a small number of firms are pursuing development of point-of-care tests that if successful could provide easier and quicker techniques to detect the coronavirus that causes COVID-19.

Among them, Bedford, UK-based Mologic said it is developing two assays using its sensitive lateral flow immunoassay platform that may enable people to use affordable self-tests and broaden test availability.

In the context of testing for the current pandemic, the push to make lab testing available at scale is the "right thing to do, but having an alternative technology in the form of point-of-care tests to support scale up is very important," Mologic Medical Director Joe Fitchett said in an interview.

In the past week a growing list of diagnostic developers leveraging PCR technology has received Emergency Use Authorization from the US Food and Drug Administration to detect the SARS-CoV-2, the coronavirus that causes COVID-19.

While a handful of firms also announced the development of point-of-care tests, using either immunoassay or PCR technology that they intend to bring to market, Mologic is developing assays on a sensitive lateral flow platform that it has been designing for infectious diseases and with an emphasis on diagnostics for epidemics.

Mologic's engineers are developing a saliva-based assay to detect coronavirus antigens and a blood-based serology test that would detect the presence of IgG and IgM antibodies generated in response to infection. Both assays would enable the reading of test results in about 10 minutes, and clinicians, as well as nurses, would deploy them prior to their being made available for self-testing, Fitchett said.

The firm anticipates that prototype assays will be ready for validation within weeks and launched with regulatory approvals, including CE marking and World Health Organization Emergency Use Listing, after three months.

According to Mologic, its lateral flow assays are part of a development program involving its ultrasensitive platform that it anticipates could attain a sensitivity of 1 picogram per milliliter, a "thousandfold improvement in sensitivity" over its current technology.

"We've done antibody engineering on novel particles that are different from gold and consist of multiple components that can be adjusted or calibrated to boost sensitivity in a lateral flow format and on a visually read, electricity-free device," Fitchett said.

The firm recently announced that it has been awarded £1 million ($1.3 million) in funding from the UK government's Department for International Development to develop the point-of-care tests to detect the coronavirus.

Fitchett said the self-tests it is developing for use in the detection of the coronavirus builds on an existing program to develop point-of-care diagnostic tests for Ebola that also involved the UK government and Wellcome Trust. Last month, Mologic announced the launch of an accelerated program with the Institut Pasteur de Dakar to develop a low-cost, high-performance rapid diagnostic test for Ebola virus disease.

Also with the Institut Pasteur de Dakar, as part of its UK funding for a POC coronavirus test, Mologic is building a manufacturing site in DiaTropix, Senegal to validate and manufacture the new tests. It anticipates the new plant will commence operations at the end of March and that it will soon kick off test validation and later conduct manufacturing at its plant in Bedfordshire.

Fitchett said the UK funding will support regulatory approvals as well as the launch and manufacturing of its tests. However, Mologic is also looking to collaborate with US-based manufacturers and commercialization partners to take the tests through the FDA's Emergency Use Authorization process and scale up manufacturing here.

It may be three months before a coronavirus self-test is deployed. According to Fitchett, such a test could be important for SARS-CoV-2 testing, especially in the event of an anticipated prolonged duration for the outbreak. It could be deployed as a rule-in, rule-out test to speed up overall testing for those patients who are deemed, based on the self-test result, to have a higher probability of being infected with the coronavirus.

"If you can layer in the lateral flow antigen assay as a triage test, you can better prioritize what you send to the lab," Fitchett said. "That's important because clinicians are already making decisions empirically. They already are saying that suspected cases need to be isolated right away, and they are not waiting for [a PCR result] to help them do that."

Further, a point-of-care antigen test that is inexpensive and easily distributed can play a role in initiatives to track and trace transmission, he said, adding that convenience and the potential to enable broader testing where laboratory facilities are not available are other reasons an affordable lateral flow test may be more useful.

"We want to ensure that low-income countries will have access to testing" because given the lack of laboratory infrastructure in those settings, they often have the greatest need for point-of-care and self-tests, Fitchett said. Mologic also plans to make the tests available at the epicenters of the pandemic, including parts of Europe and in the US.

While its antigen point-of-care test would be deployed to directly detect the coronavirus, point-of-care serology testing will be needed for the testing of patients who have been in isolation and are recovering or have recovered from COVID-19, he said.

Antibodies detected by a serology test indicate that a person had an immune response to SARS-CoV-2. According to the US Centers for Disease Control and Prevention, serology tests are particularly important for detecting infections with few or no symptoms.

The CDC is developing a laboratory test to determine how much of the US population has been exposed to SARS-CoV-2, and the FDA recently recognized that serology tests could play a role in testing during the pandemic.

On Monday, as part of an announcement to dramatically alter its enforcement discretion over local labs and test kit manufacturers, the FDA provided recommendations for test developers "who may wish to develop serological tests for use during this coronavirus outbreak."

"We recognize that serology tests are less complex than molecular tests and are solely used to identify antibodies, which limits their effectiveness for diagnosis," the FDA said. However, the agency "does not intend to object to the distribution and use of serology tests to identify antibodies to SARS-CoV-2 where the test has been validated, notification is provided to the FDA, and warning statements are included with the tests."

Companies other than Mologic are exploring the development and launch of point-of-care assays to detect the coronavirus including Credo Diagnostics Biomedical, Mesa Biotech, and Shanghai Liangrun Biomedicine Technology

In the context of immunoassay test development, SVB Leerink analyst Puneet Souda said in a research note this week, "COVID-19 immunoassay timelines are likely to be lengthy, while performance might not be comparable to existing RT-PCR assays." He further noted that an antibody immunoassay is likely to suffer more from false positives and false negatives than an RT-PCR assay.

The public health system in the US "must adapt much better and faster to the new normal of emergency preparedness for highly infectious diseases, and new diagnostic tests must be both highly sensitive and highly specific…for SARS-CoV-2, the pandemic virus," said Gerald Kost, director of the point-of-care testing center at the University of California, Davis.

Kost recently noted in a paper published in Frontier in Public Health that geospatial strategies ─ the time, place, and space for procuring samples, and testing safely in drive through or pop-up settings ─ now dominate point-of-care testing during epidemics.

With reference to point-of-care tests being developed by Mologic and other companies, he said that it is important to note that healthcare providers of different skill levels are interfacing with the public, so the test must be highly accurate and testing highly reliable. "We do not want infected people [with false negative test results] unknowingly walking around spreading the disease," he said.