A simple glucose meter test can tell if you have antibodies
A simple glucose meter test can tell if you have antibodies

A simple glucose meter test can tell if you have antibodies

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Researchers say new glucose meter-based tests may help measure antibody levels against SARS-CoV-2. Andriy Onufriyenko / Getty Images
  • Current assays that can accurately measure antibody levels against SARS-CoV-2 – the virus that causes COVID-19 – is expensive, time consuming and requires sophisticated detection systems.
  • However, researchers have now developed a rapid and cost-effective antibody analysis that can quantify antibody levels using glucose meters commonly used to measure blood sugar levels.
  • The sensitivity of this new glucose meter-based antibody assay was similar to the current ‘gold standard’ assays, and the test could also be adapted to other medical conditions.

Researchers at Johns Hopkins University have developed a new rapid assay that can detect antibodies to SARS-CoV-2 using widely available glucose meters. This new glucose meter-based antibody assay is easier to perform and more cost-effective than current gold standard assays.

One of the co-authors of the study Dr. Jamie SpanglerProfessor at Johns Hopkins University, said: “This work presents an innovative approach to democratizing the availability of immune protection data by acquiring commercial glucometers to quantitatively measure disease-targeted antibody levels.”

Dr. Eliah Aronoff-Spencera professor of medicine at the University of California, San Diego, said: “While there are notable barriers to the development of field diagnostics using off-the-shelf glucometers, studies like these highlight a possible future where home diagnosis is just as inexpensive. and exactly as glucose detection. At this point, we want a transformation in global surveillance and personal disease detection. ”

The study appears from Journal of the American Chemical Society.

The tests to diagnose COVID-19 detect the presence of viral genetic material or proteins. In contrast, assays measuring antibodies to SARS-CoV-2 can help assess previous exposure to the virus.

These antibodies include IgG antibodies, which is the predominant type of antibodies found in the blood. IgG antibodies play a crucial role in producing an immune response against bacteria and viruses, including SARS-CoV-2.

In particular, these IgG antibodies persist for several months after a SARS-CoV-2 infection or after receiving a COVID-19 vaccine.

IgG antibody levels are predictive of the degree of protection against a symptomatic SARS-CoV-2 infection. Thus, evaluation of antibody levels in the population can help determine how long immunity to COVID-19 lasts after vaccination or a previous infection.

The emergence of new SARS-CoV-2 variants has also raised fears of declining immunity, making it crucial to assess levels of immune protection in the population. Thus, determining antibody levels against SARS-CoV-2 can help guide policy decisions about the need for booster shots.

Enzyme-linked immunosorbent assays (ELISAs) is the gold standard for measuring antibody levels. However, accurate quantification of antibody levels using ELISAs requires that blood samples be sent to specialized laboratories due to the need for expensive detection equipment. As a result, performing these assays is time consuming, expensive, and requires skilled technicians.

Although rapid ELISA tests have been developed for use in the clinic, these tests provide only qualitative information and remain expensive. Thus, there is a need for cost-effective and widely available alternatives to ELISAs that can be used by clinicians or the general public.

To overcome these limitations associated with ELISAs, researchers have developed tests which are compatible with glucose meters. Using commercially available glucose meters for antibody detection can reduce the cost of detection and the need for skilled technicians.

These tests involve antibodies or other detection molecules coupled with the enzyme invertase, which breaks down sucrose or sugar into glucose. The antibodies coupled with invertase bind to the protein of interest in a sample and produce glucose upon introduction of a sucrose solution. The amount of glucose produced is proportional to the amount of protein of interest and can be detected by a glucose meter.

However, coupling of antibodies with invertase has proved difficult. In some studies, researchers have indirectly coupled invertase with antibodies using intermediate compounds such as nanoparticles. However, such an approach can cause variation in the amount of coupling and produce inconsistent results.

Researchers at Johns Hopkins University have now developed a new assay involving antibodies directly linked to two invertase molecules. The researchers used genetically modified laboratory-grown cells to express these antibodies fused to invertase molecules.

In contrast to indirect coupling, the genetic fusion of the antibody and the invertase enzyme ensures that a uniform number of invertase molecules are attached to the antibody. These antibodies coupled with invertase can bind to all human IgG antibodies.

The new assay uses a plastic strip coated with the SARS-CoV-2 spike protein. After incubating the strip with blood samples from those with a history of COVID-19, the SARS-CoV-2 specific antibodies selectively bind to the tip proteins covering the surface of the strip.

After rinsing the strip to remove the non-specific antibodies, the strip is first transferred to a solution containing the antibody-invertase fusion protein and then to a sucrose solution.

The SARS-CoV-2 specific IgG antibodies bound to the nail protein on the strip can then be detected by the antibody-invertase fusion protein. The invertase enzyme subsequently degrades sucrose to glucose, which can be detected by a glucose meter. The assay produces glucose relative to the SARS-CoV-2-specific IgG antibodies in the blood sample.

In this study, the researchers found that the glucose meter-based antibody-invertase protein assay could accurately detect IgG antibodies to SARS-CoV-2, and its performance was comparable to commercially available ELISAs.

The antibody-invertase fusion protein recognizes all IgG antibodies produced by the human body, making this assay versatile.

“The immediate goal of this technology is to scale up production to allow broad rollout. We hope to use new data from this platform to correlate disease protection with antibody levels across a wide range of topics,” said Dr. Spangler.

The assay could be used against other conditions by coating the strip with a protein other than the wild-type SARS-CoV-2 spike protein. For example, strips coated with the tip protein from a SARS-CoV-2 variant could be used to measure antibody levels against this variant.

“We imagine that the assay we have developed can be adapted to detect antibodies against future variants of SARS-CoV-2 virus as well as against other infectious diseases. The assay can also be used to detect antibodies in connection with other conditions such as cancer. , autoimmune disorders, allergies or transplants. “
– Dr. Jamie Spangler

“This technology can offer important scientific insights and also inform decisions related to medical interventions and public health policies. In addition, the versatile nature of this platform allows it to be easily adapted to target a range of disease applications in addition to infection,” added Dr. Spangler.

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