The most complete picture to date sheds light on how antibodies produced in humans that effectively fight SARS-CoV-2 work to neutralize the part of the virus responsible for causing infection. In the magazine Science, researchers at the University of Texas at Austin describe the discovery, which is good news for the design of the next generation of vaccines to protect against variants of the virus or future emerging coronaviruses.
Previous research has focused on a group of antibodies that target the most obvious part of the virus’s crown protein, called the receptor-binding domain (RBD). Because RBD is the part of the thorn that attaches directly to human cells and allows the virus to infect them, it was rightly considered to be a major target of the immune system. However, by testing blood samples from four people who had recovered from SARS-CoV-2 infections, the researchers found that most of the antibodies circulating in the blood – an average of about 84% – target areas of the viral protein peak outside RBD. and, apparently, with good reason.
“We found that these antibodies painted the entire thorn, both the arch and the stalk of the thorn protein, which looks a bit like an umbrella,” said correspondent Greg Hipolito, a research associate professor at UT Austin’s Molecular Biosciences department and assistant professor of oncology at Dell University Medical School. “The immune system sees the whole jump and tries to neutralize it.”
Many of those who do not target RBD antibodies, identified by the team, act as a powerful weapon against the virus, targeting a region in part of the spike protein located in what would be the canopy of the umbrella called the N-terminal domain ( NTD). These antibodies neutralize the virus in cell cultures and have been shown to prevent a lethal version of the virus adapted to mice from infecting mice.
NTD is also part of the viral protein spike, which often mutates, especially in several variants of concern. This suggests that one of the reasons these options are so effective in evading our immune system is that they can mutate around one of the most common and powerful types of antibodies in our arsenals.
“There is an evolutionary arms race between the virus and our immune system,” said Jason Lavinder, a research associate in the McKetta Chemical Engineering Department and co-author of the new study. “We all develop a standard immune response to this virus, which involves targeting this one site and which puts selective pressure on the virus. But then the virus also exerts its evolutionary power, trying to change around our selective immune pressure.”
Despite these SARS-CoV-2 maneuvers, the researchers say that about 40% of the circulating antibodies are directed to the stem of a protein called the S2 subunit, which is also a part that the virus doesn’t seem to be able to change easily.
“It’s reassuring,” Hipolito said. “This is an advantage that our immune system has. It also means that our current vaccines elicit antibodies targeting this S2 subunit, which probably provides another layer of protection against the virus.”
This is also good news for designing vaccine amplifiers or next-generation vaccines against dangerous variants, and even for developing a vaccine that can protect against future pandemics from other strains of the coronavirus.
“This means that we have a strong rationale for developing a next generation of vaccines against SARS-CoV-2 or even a pan-coronavirus vaccine that targets each strain,” Hipolito said.
Researchers at UT Austin are among several in the world who are now working to develop a single coronavirus vaccine to fight infection from all coronaviruses, not just SARS-CoV-2.
Vaccine-induced antibodies may be less effective against several new variants of SARS-CoV-2: a study
“Preliminary, protective and convergent IgG recognition of SARS-CoV-2 non-RBD spike epitopes,” Science (2021). science.sciencemag.org/cgi/doi… 1126 / science.abg5268
Provided by the University of Texas at Austin
Quote: Our immune system covers the SARS-CoV-2 protein with antibodies (2021, May 4), extracted on May 5, 2021 from https://medicalxpress.com/news/2021-05-immune-blanket-sars-cov-spike – protein.html
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