How antibodies in the immune system target and attack certain viruses, especially the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the pathogen that causes coronavirus disease (COVID-19) Still unknown.
In a new study recently published in the journal Science, A team of researchers in the United States have discovered most of the antibodies that circulate in the blood target areas of the virus. Spike protein Outside the receptor binding domain (RBD), the portion of the spike that directly binds to human cell receptors.
The team found that the SARS-CoV-2 antibody covered the entire peaplomer, including an umbrella-like arc and stem.
The molecular composition and binding epitope of immunoglobulin G (IgG) antibody that circulates in plasma after SARS-CoV-2 infection is still unknown.
Past studies have focused on a group of antibodies that target RBD, a major region of coronavirus peplomer. Scientists have studied these antibodies because RBD is part of the virus that attaches directly to the angiotensin converting enzyme 2 (ACE2) receptor expressed in human host cells, a mechanism that promotes viral invasion. ..
The SARS-CoV-2 spike external domain (S-ECD) folds into a multi-domain structure that contains RBD, which is essential for virus infectivity and the adjacent N-terminal domain (NTD).
Humoral immunity against spiked glycoproteins may provide protection and is a major antigenic target for current vaccines and monoclonal antibodies (mAbs). However, the identity, abundance, and clonality of the IgG plasma antibody repertoire and its targeted epitopes remain unclear.
To characterize the IgG repertoire, the team collected blood samples during the early convalescent period of four patients with COVID-19. These patients experienced only mild symptoms and showed plasma virus neutralizing titers.
Researchers have found that approximately 84% of antibodies in the blood target region beyond RBD act like a blanket over the entire peplomer. The immune system detects the entire peaplomer and attempts to neutralize it.
Most of the antibodies that were not directed to the detected RBD targeted NTDs and neutralized the virus in cell culture. Because NTDs are primarily part of the frequently mutated peplomer, developing vaccines and drugs that target this area can stop an ongoing pandemic.
Frequent mutations in the SARS-CoV-2 peplomer can impair the immune system’s ability to quickly detect and neutralize the virus. Researchers have noticed that there is competition between the virus and the body’s immune system. The body develops a standard immune response to the virus, which competes to mutate to evade the immune system. This process of mutual evolution is described as a biological arms race.
Studying how antibodies target and attack viruses is important for developing more powerful and effective vaccines and treatments.
In a nutshell, researchers have revealed that: Convalescent plasma The IgG response to SARS-CoV-2 is oligoclonal and focuses on the RBD region.This is strongly included Neutralizing antibody Against NTD.
Anti-NTD antibodies dominate in some people and can affect levels of contribution to defense.
Our findings that mutations present in circulating SARS-CoV-2 mutants may impair or eliminate binding and neutralization by public anti-NTD antibodies have led to the mechanism of viral escape in a subset of the population. It could be composed, “the researchers said in a study.
“These data show that’public’NTD-oriented and other non-RBD plasma antibodies are prevalent and affect SARS-CoV-2 protection and antibody escaping,” they conclude. I did.
The COVID-19 pandemic continues to cause havoc around the world. To date, approximately 154.46 million people have been infected with SARS-CoV-2. Of these, 3.23 million died from the infection and about 91 million recovered.
The United States, India, and Brazil have the highest number, with 32.51 million, 20.66 million, and 14.85 million, respectively.
The death toll is over 578,000 in the United States, 411,000 in Brazil and 226,000 in India.
Studies have shown that approximately 84% of antibodies in plasma target the non-RBD epitope of the SARS-CoV-2 peplomer.
Source link Studies have shown that approximately 84% of antibodies in plasma target the non-RBD epitope of the SARS-CoV-2 peplomer.