Do You Have Covid-19 Antibodies? New Glucose Meter Can Tell You

Researchers made test strips with the SARS-CoV-2 spike protein on them. When the strips were dipped in Covid-19 patient samples, the patients' SARS-CoV-2 antibodies bound to the spike protein. 

A new glucose meter could detect SARS-CoV-2 antibodies in patient samples

Source : American Chemical Society

Covid-19 tests can determine whether a person is infected with SARS-CoV-2, but cannot assess how long one who has tested positive for the novel coronavirus is protected against reinfection. A team of researchers has recently reported a simple, accurate glucose-meter-based test incorporating a novel fusion protein. The researchers have described in a new study that consumers could someday use this assay to monitor their own SARS-CoV-2 antibody levels. The study titled "Antibody-Invertase Fusion Protein Enables Quantitative Detection of SARS-CoV-2 Antibodies Using Widely Available Glucometers" was recently published in the Journal of American Chemical Society. 

Antibodies Are A Good Indication Of Protection Against SARS-CoV-2

Though vaccines against SARS-CoV-2 and infection with the virus can guard against future infections for a while, the duration of the protection is not known exactly. A person's level of SARS-CoV-2 is a good indication of immune protection. The enzyme-linked immunosorbent assay (ELISA) is the gold standard measurement, but requires expensive equipment and specialised technicians. 

Meanwhile, glucose meters are readily available, easy to use, and can be integrated with remote clinical services. According to the statement, researchers have been adapting glucose meters to sense other target molecules, so that they can perform the dual action of detection and glucose production. 

How Does The Glucose Meter Work?

For instance, if a detection antibody in the test binds to an antibody in a patient's blood, a reaction occurs that produces glucose. This is something that the device detects very well. 

Though invertase is an attractive enzyme for this type of analysis as it converts sucrose into glucose, it is difficult to attach the enzyme to detection antibodies with chemical approaches. 

Therefore, researchers at the American Chemical Society set out 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. 

According to the study, the scientists designed and produced a novel fusion protein containing both invertase and a mouse antibody that binds to human immunoglobulin (IgG) antibodies. They found that the fusion protein bound to human IgGs and successfully produced glucose from sucrose. 

Then, the researchers made test strips with the SARS-CoV-2 spike protein on them. When the strips were dipped in Covid-19 patient samples, the patients' SARS-CoV-2 antibodies bound to the spike protein. 

Since the invertase/IgG fusion protein, and sucrose were added to the strips, it led to the production of glucose. This could be detected by the glucose meter. The scientists validated the test by performing the analysis with glucose meters on a variety of patient samples. They found that the new assay worked, along with four different ELISAs. According to the researchers, the method can also be adapted to test for SARS-CoV-2 variants and other infectious diseases.