Over-the-counter COVID tests can quickly show whether you are infected with SARS-CoV-2. But if you have a positive result, there’s no equivalent at-home test to assess how long you’re protected against reinfection. In the Journal of the American Chemical Society, researchers now report a simple, accurate glucose-meter-based test incorporating a novel fusion protein. The researchers say that consumers could someday use this assay to monitor their own SARS-CoV-2 antibody levels.
Vaccines against SARS-CoV-2 and infection with the virus itself can guard against future infections for a while, but it’s unclear exactly how long that protection lasts. A good indication of immune protection is a person’s level of SARS-CoV-2 antibodies, but the gold standard measurement—the enzyme-linked immunosorbent assay (ELISA)—requires expensive equipment and specialized technicians.
Enter glucose meters, which are readily available, easy to use and can be integrated with remote clinical services. Researchers have been adapting these devices to sense other target molecules, coupling detection with glucose production. For example, if a detection antibody in the test binds to an antibody in a patient’s blood, then a reaction occurs that produces glucose—something the device detects very well. Invertase is an attractive enzyme for this type of analysis because it converts sucrose into glucose, but it’s difficult to attach the enzyme to detection antibodies with chemical approaches. So, Netzahualcóyotl Arroyo-Currás, Jamie B. Spangler and colleagues wanted to see whether producing a fusion protein consisting of both invertase and a detection antibody would work in an assay that would allow SARS-CoV-2 antibody levels to be read with a glucose meter.
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