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People infected with the original strain of the virus that causes COVID-19 at the start of the pandemic produced a consistent antibody response, creating two main groups of antibodies to bind to the spike protein on the outer surface of the virus. However, these antibodies do not bind well to the newer variants, a new study from the University of Illinois Urbana-Champaign has found.
Characterizing the types of antibodies the body is most likely to make to fight a natural infection is an important roadmap for vaccine design, says study leader Nicholas Wu, professor of biochemistry in Illinois. His research team published their findings in the journal Nature Communications.
“The antibody response is quite relevant to everything from understanding natural infection and how we recover from infection to designing a vaccine. The body has the ability to produce various antibody responses – it is estimated that we could make a trillion different antibodies. So when you see people making pretty similar antibodies against a particular virus, we call it a convergent antibody response, ”Wu said.“ This means we can design vaccines by trying to elicit this type of antibody response. , and this will likely improve the responsiveness of more people to the vaccine. “
The researchers extracted published articles on COVID-19 patients to obtain data on the sequence of the antibodies they produced. They focused on antibodies against the spike protein, the part of the virus that binds to receptors in human cells to infect them. The spike protein is the target of most vaccines.
They found that many antibody sequences converged into two main clusters, indicating a consistent human immune response to the virus, said graduate student Timothy Tan, the study’s first author.
“We really focused on characterizing the antibodies created in people infected with the original strain of the virus,” Tan said. “Before we started the study, variations were not much of a problem. As they emerged, we wanted to see if the common antibodies we had identified were able to bind to new variants. “
Researchers studied the ability of convergent antibodies to bind to several variants and found that they no longer bind to some. The discovery has implications for the ability of new variants to re-infect people who contracted previous versions of the virus, as well as the continued effectiveness of vaccines and the design of possible vaccine boosters, Wu said.
“Even though this antibody response is very common with the original strain, it doesn’t really interact with the variants,” Wu said. “This, of course, raises concern that the virus will evolve to escape the body’s main antibody response Some antibodies should always be effective – the body makes antibodies against many parts of the virus, not just the spike protein – but the particular groups of antibodies we saw in this study will not be too effective. “
The researchers said they would like to conduct similar studies characterizing antibody responses to delta and other variants, to see if they also produce a convergent response and how it differs from the original strain.
“We want to design vaccines and boosters, if needed, that can protect a majority of the population,” Tan said. “We expect the antibody response to these variants to be quite different. When we have more data on the antibodies of patients infected with variants, understanding the difference in the immune response is one of the directions we would like to pursue. ”
Reference: Tan TJC, Yuan M, Kuzelka K, et al. Sequence signatures of two public antibody clonotypes that bind to the binding domain of the SARS-CoV-2 receptor. Nat Common. 2021; 12 (1): 3815. doi: 10.1038 / s41467-021-24123-7
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