8/26/2023 0 Comments Antigenic shift covid 19Notably, these antibodies are effective against many related coronaviruses. These antibodies could still effectively bind and neutralize the virus even in the presence of the mutations of interest. The researchers also tested antibodies that bind to parts of the spike protein outside of the RBS. “This work provides a structural explanation for why antibodies elicited by COVID-19 vaccines or natural infection by the original pandemic strain are often ineffective against these variants of concern,” Wilson says. Changing either amino acid would disrupt these interactions and interfere with antibody binding. Antibodies from the two main classes almost always interact with the amino acid at position 417 or 484 when binding to the RBS. They analyzed the molecular structures of more than 50 human antibodies bound to the SARS-CoV-2 spike protein. The researchers investigated why these mutations prevent antibody binding and neutralization. But the mutation at position 501 offset this effect by enhancing host cell binding. The position 417 mutation also weakened virus binding to host cells. The mutations at positions 417 and 484 prevented binding by antibodies from these classes. Most antibodies elicited against SARS-CoV-2 belong to two main classes. The research team tested how well antibodies from COVID-19 patients bound to viruses that had these mutations. The variants first identified in South Africa and Brazil share mutations in three locations in the RBS: 417, 484, and 501. This can, in turn, alter the protein’s structure and function. A mutation in the viral genome can lead to an amino acid getting replaced by one of a different type. Proteins like the SARS-CoV-2 spike consist of long chains of building blocks called amino acids that fold into a specific shape. NIH’s National Institute of Allergy and Infectious Diseases (NIAID) supported the research, which appeared in Science on May 20, 2021. Ian Wilson at the Scripps Research Institute examined how and why certain mutations protect the virus. It raises concerns that new variants could make existing vaccines less effective and draw out the pandemic. This allows the variants to partially escape the immune response produced after vaccination or prior infection. Some of these mutations render antibodies elicited against earlier virus strains less effective. Recent SARS-CoV-2 variants contain changes, or mutations, at a key site on the spike protein called the receptor-binding site (RBS). SARS-CoV-2, the virus that causes COVID-19, uses a protein called the spike protein to recognize and enter host cells. Scientists gained insights into how SARS-CoV-2 variants (blue) may escape neutralization from antibodies (yellow).
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