Venture Producing Covid-19 Antibody Test Kits

Scanning electron microscope image of SARS-Cov-2 virus, in orange, emerging from cells (NIAID, Flickr)

20 May 2020. A new company formed from a medical research lab is producing test kits for detecting and measuring a person’s Covid-19 antibodies. Kantaro Biosciences is a joint venture of Mount Sinai medical center and diagnostics company Renalytix AI, both in New York.

Screening for SARS-CoV-2 virus antibodies in people previously infected can help determine if a person may donate convalescent plasma with those antibodies as a treatment for others with the disease. Donations from recovered patients are being encouraged, and the Food and Drug Administration issued regulatory guidance for the use of convalescent plasma during the pandemic. Tracking the presence of antibodies can also show the spread of infections through the population and make it possible to more precisely track the course of immune responses to the virus.

A team led by Mount Sinai microbiology and virology professor Florian Krammer designed a screening test for SARS-CoV-2 antibodies using standard blood samples and analytical lab techniques. The test detects the presence of antibodies with synthetic antigen proteins aimed at proteins in two types of the virus’s spikes, the part of the virus that penetrates and infects cells, and its receptor binding domain. In addition, the test measures the concentrations of antibodies, known as titers, in a person’s blood.

Because the test uses synthetic antigen proteins, no live viral components are involved. And blood samples are analyzed with the enzyme-linked immunosorbent assay or ELISA. That assay, a system found in most licensed diagnostic labs, identifies and measures the number of antigens in blood samples.

Krammer and colleagues describe the antibody test in the 12 May issue of the journal Nature Medicine. The paper reports all blood samples from former infected patients reacted strongly in the test, and samples from non-infected patients or those with other infections gave no false-positive signals.

A FDA review of commercial antibody tests shows the Mount Sinai test has a sensitivity or true positive rate of 93 percent and a specificity or true negative rate of 100 percent. The test received emergency authorizations from New York State health authorities and FDA, and has been used by Mount Sinai to test for antibodies in blood samples that so far produced convalescent plasma treating more than 250 patients.

“Antibody testing,” says Krammer in a Mount Sinai statement, “will be critical to providing patients and governments the essential information they need to help the world economies reopen and begin to recover from Covid-19.”

Kantaro Biosciences is a joint venture of Mount Sinai and Renalytix AI Inc., also a spin-off company from Mount Sinai. Kantaro is designing disease diagnostics beginning with its SARS-CoV-2 antibody test kits. Renalytix AI is developing an algorithm-driven diagnostic test for early-stage chronic kidney disease which, as reported by Science & Enterprise in May 2019, received a breakthrough device designation from FDA.

In addition, medical test manufacturer Bio-Techne Corp. in Minneapolis agreed to begin manufacturing and distribution of Kantaro’s antibody test kits. Kantaro and BioTechne expect to produce some 10 million antibody test kits per month by July.

More from Science & Enterprise:

• Antibody Neutralizes Covid-19, SARS Viruses
• Microsoft, Biotech Examine Covid-19 Immune Response
• Biotech Gains Antibody Discovery, Manufacturing Funds
• Univ Building Single Covid-19 Diagnostic, Antibody Test
• Fast, Simple Covid-19 Antibody Test Being Developed

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