Human immune systems have been in the war for a very long time and perhaps have evolved ways of dealing with viral variants, since most viruses mutate.
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Your Immune System Evolves to Fight Coronavirus Variants - Scientific American
Your Immune System Evolves to Fight Coronavirus Variants
Antibodies can change to counter new forms of the shape-shifting virus, research hints
A lot of worry has been triggered by discoveries that variants of the pandemic-causing coronavirus
can be more infectious than the original. But now scientists are starting to find some signs of hope on the human side of this microbe-host interaction. By studying the blood of COVID survivors and people who have been vaccinated, immunologists are learning that some of our immune system cells—which remember past infections and react to them—might have
their own abilities to change, countering mutations in the virus. What this means, scientists think, is that the immune system might have evolved its own way of
dealing with variants.
“Essentially, the immune system is trying to get ahead of the virus,” says Michel Nussenzweig, an immunologist at the Rockefeller University, who conducted some recent studies that tracked this phenomenon. The emerging idea is that the body maintains reserve armies of antibody-producing cells in addition to the original cells that responded to the initial invasion by SARS-CoV-2, the virus that causes COVID. Over time some reserve cells mutate and produce antibodies that are better able to recognize new viral versions. “It’s really elegant mechanism that that we’ve evolved, basically, to be able to handle things like variants,” says Marion Pepper, an immunologist at the University of Washington, who was not involved in Nussenzweig’s research. Whether there are enough of these cells, and their antibodies, to confer protection against a shape-shifting SARS-CoV-2 is still being figured out.
Last April, when the pandemic was reaching its first peak in New York City, Nussenzweig and his colleagues sprang into action and began collecting the blood of COVID survivors. There were disturbing early reports of reinfection and waning antibodies, and the scientists wanted to understand how long the immune system could sustain its ability to respond to the novel threat. They took blood samples from people who had been hit by SARS-CoV-2 one month after the infection and then again six months later. What the scientists found was somewhat encouraging. Blood collected at the later date did have lower levels of circulating antibodies, but that made sense because the infection had cleared. And levels of the cells that make antibodies, called memory B cells, remained constant or even increased in some people over time. After an infection, these cells hang around in the body’s lymph nodes and maintain the ability to recognize the virus. If a person gets infected a second time, memory B cells activate, quickly produce antibodies and block the virus from creating a second serious infection.
In a follow-up test, the Rockefeller scientists cloned these reserve B cells and tested their antibodies against a version of SARS-CoV-2 designed to look like one of the new variants. (The experimental virus lacked the ability to replicate, which made it safer to use in the lab.) This virus had been genetically engineered to have specific mutations in its spike protein, the part of the coronavirus that attaches to human cells. The mutations mimicked a few of the ones currently found in the variants of concern. When researchers tested the reserve cells against this mutated virus, they saw some cells produced antibodies that glommed on to the mutated spike proteins—even though these spikes were different than those on the original virus. What this means is that the antibodies had changed over time to recognize different viral features. The research was published in
Nature in January. “What the paper shows us is that, in fact, the immune response is evolving—that there’s some dynamic changes over this period of time,” Nussenzweig says.
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