Virus Variants Can Elude Antibodies, Suggesting Need For COVID Vaccine Booster Shots
Some coronavirus variants are able to dodge infection-fighting antibodies, researchers at Washington University have found.
Although the antibodies tested prevent the original virus from infecting cells, the study finds three fast-spreading variants have mutations that can help them evade these immune cells.
As these new iterations of the virus become more widespread, scientists are racing to understand the possible implications for COVID-19 vaccines and treatments.
The Washington University study highlights a troubling trend: While some antibodies remained effective, it generally took more of them to quash the new variants compared to the original virus. The results, along with a growing body of research worldwide, suggest vaccines and treatments may need to be updated in the future.
Like all viruses, the coronavirus accumulates tiny copying errors, or mutations, as it replicates inside cells. Most are minor, but occasionally, a mutation will make the virus more contagious or help it elude immune responses. When these rare mutations do arise, they can spread rapidly.
“This virus is changing over time,” said Michael Diamond, professor of medicine at Washington University and study co-author. “And my suspicion is that this will continue.”
Coronavirus variants, viruses that share the same set of inherited genetic mutations, have sprung up around the globe in recent months. These variants have a slew of mutations, including in the tiny, prong-like projections known as spike proteins that allow the virus to enter human cells.
Because immune cells bind to the spike protein, scientists used it as a type of template for designing vaccines and mass-produced, synthetic immune cells known as monoclonal antibodies. They’re now feverishly working to understand if certain mutations in the variants could undermine future efforts to control the virus.
“For many of these antibodies, we have a huge amount of data on exactly how they bind to the spike protein,” Diamond said. “So when new variants begin to emerge, we can already predict, ‘That antibody might have a problem, we need to test it.’”
Putting antibodies to the test
The Washington University team tested three variants first identified in the U.K., South Africa and Brazil against a panel of neutralizing antibodies in the lab, which latch on to the virus and keep it from infecting cells.
Some were lab-made antibodies used to treat COVID-19, while others were collected from the blood of patients who had recently recovered from the illness or received the Pfizer vaccine.
A number of the antibodies tested were still able to successfully bind to the virus variants. But depending on which antibody was used, it took about three to 10 times more of the immune cells to wipe out the variants identified in Brazil and South Africa.
Still, these antibodies are not the only way the immune system controls viruses, said Washington University graduate student and co-author Rita Chen.
“You potentially have other arms of immunity that could keep you from getting sick or developing severe disease,” Chen said. Some components of the immune system, such as T-cells, weren’t included in the study, she added, but “could confer protection if you were infected with a variant.”
Beyond putting antibodies to the test, the team tried to narrow down which of the many mutations might help the variants elude the immune system by creating a suite of viruses, each with a single mutation.
“New mutations crop up all the time,” Chen said. “But the question leading into this study was, which mutations in these new variants actually matter?”
As it turns out, a single mutation matters quite a bit.
One minuscule change on the variants’ spike protein, known as E484K, played a major role in whether or not antibodies were effective against the variants first identified in South Africa and Brazil.
Other researchers have identified this mutation as an important one, and it’s been found in other variants that are antibody-resistant, including a version circulating in New York and another in Oregon.
While it’s unclear whether these variants will pose new threats to public health or undermine vaccines, Diamond said, it’s critical to continue monitoring their spread and evaluating how they interact with antibodies.
“All of these studies, our study and others, say, ‘Hey, we really need to watch this,’” Diamond said. “And while we're watching it, we should start the process of a backup plan,” by developing booster shots and tweaking COVID-19 antibody treatments.
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