As SARS-CoV-2 continues to evolve, knowing your immunity—both from vaccines and infections—will become increasingly important.
Antibodies against COVID-19 are the best substitute for immunity against the disease. But they currently require a healthcare provider to order the test, which must be done at a pharmacy or doctor’s office. The sample is then sent to a laboratory for analysis – all of which takes time, making the process inconvenient and too burdensome for most people.
Johns Hopkins researchers have discovered a way to potentially make antibody testing much more affordable. They developed a method to use widely available and relatively inexpensive glucometers – small devices that read blood sugar levels from a finger prick – to detect antibodies against SARS-CoV-2.
IN paper published in June in Journal of the American Chemical Societythe research team described how they developed a way to attach antibodies to SARS-CoV-2 to sugar and then have a glucose reader measure those sugar levels, which reflect antibody levels.
“We can manipulate the contents of the test strip to see if we can better understand where this immunity comes from and how long it lasts,” said Dr. Netz Arroyo, senior author of the paper and assistant professor of pharmacology and molecular sciences at John Hopkins.
Although antibodies do not make up the entire human immune response to a virus, they are an important window into the defenses that people build. Antibodies are usually the first line of defense against the microbe, and once antibodies are generated, then other immune cells, including T cells, step in to broaden and amplify the response.
Arroyo was inspired to develop the system after remembering the 2011 paper he read as a graduate student in 2014 describing a similar system. As the pandemic unfolded in 2020, testing was slow and cumbersome, leaving public health officials blind to how much virus was circulating and how much immunity people were developing. “I immediately came up with the idea of using a glucometer,” he says.
Arroyo and other Johns Hopkins researchers set out to develop a protein that would stick to antibodies against COVID-19 and could be placed on a test strip, then create a way for a glucose meter to read the test strip. In the first version, the group used blood samples, but eventually a finger prick was enough for the test, Arroyo says. Researchers are exploring ways to make the test even more accessible by using other samples such as saliva or mouth swabs that also contain antibodies.
Another major advantage of the system is that it can be generalized to any infectious agent; scientists just need to change the target to which the sugar binds. “We wanted to implement a way that would affect not only this pandemic, but also future epidemics or pandemics,” says Arroyo.
This means the test can also be used to measure antibodies against monkeypox and provide doctors with valuable information about how well vaccine, Jynneos, works, says Arroyo. The vaccine was approved based on limited information about monkeypox in humans—and it is now it is given in a different way to increase supply – so being able to easily track antibodies in vaccinated people will give scientists a better understanding of efficacy and how quickly people become protected.
Information about immunity to SARS-CoV-2 may become more important in the coming months and years as the world learns to live with COVID-19. Understanding how long protection lasts after each infection or booster dose will help health authorities provide better advice on how often injections should be given. Because the test can also be modified to detect different variants, health experts can also get a better idea of whether people’s protection from vaccines is effective against the latest circulating variants.
To detect the antibodies, the researchers’ system now requires three steps, each of which involves treating the blood to different reactions. But researchers are working on ways to streamline the process to make it similar to the one-step process that at-home COVID-19 tests use. The university’s Office of Technology Enterprises will license the test to companies interested in developing it further.
“The goal is to better understand immunity against COVID-19 and other diseases,” says Arroyo. This type of test is “a powerful tool for monitoring what is happening in our population and can inform policy decisions.”
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