《Medicalxpress,1月21日,Study: Omicron evades some but not all monoclonal antibodies》

  • 来源专题:COVID-19科研动态监测
  • 编译者: YUTING
  • 发布时间:2022-02-10
  • Several, but not all, of the human monoclonal antibodies used clinically to prevent patients from becoming severely ill from COVID-19 may not be protective against the omicron variant now sweeping across the United States, researchers reported Jan. 19 in the journal Nature Medicine.

    The laboratory study, led by researchers at Washington University School of Medicine in St. Louis, Missouri, tested five antibody combinations including precursor antibodies discovered at Vanderbilt University Medical Center that subsequently were optimized by AstraZeneca and which were authorized for emergency use in patients last month.

    Several antibodies, including those in clinical use by Celltrion, Regeneron and Eli Lilly, completely lost the ability to neutralize the omicron variant in cell culture, whereas the antibodies discovered at VUMC had a reduced neutralizing ability, and an antibody developed by Vir Biotechnology was minimally affected, the study found.

    "Omicron escapes recognition by several of the monoclonal antibodies that are being used for therapy," said James Crowe Jr., MD, director of the Vanderbilt Vaccine Center, whose team discovered the monoclonal antibodies later optimized by AstraZeneca into a long-acting antibody combination called Evusheld.

  • 原文来源:https://medicalxpress.com/news/2022-01-omicron-evades-monoclonal-antibodies.html
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  • 《Medicalxpress,1月7日,Omicron resistant to most monoclonal antibodies but neutralized by a booster dose》

    • 来源专题:COVID-19科研动态监测
    • 编译者:YUTING
    • 发布时间:2022-01-17
    • The Omicron variant was detected for the first time in South Africa in November 2021 and has since spread to many countries. It is expected to become the dominant variant within a few weeks or months. Initial epidemiological studies show that the Omicron variant is more transmissible than the currently dominant virus (the Delta variant). It is capable of spreading to individuals who have received two vaccine doses and to previously infected individuals. Scientists from the Institut Pasteur and the Vaccine Research Institute, in collaboration with KU Leuven (Leuven, Belgium), Orléans Regional Hospital, Hôpital Européen Georges Pompidou (AP-HP), Inserm and the CNRS, studied the sensitivity of the Omicron variant to monoclonal antibodies used in clinical practice to prevent severe forms of the disease in people at risk, as well as to antibodies in the blood of individuals previously infected with SARS-CoV-2 or vaccinated. They compared this sensitivity with that of the Delta variant. The scientists demonstrated that Omicron is much less sensitive to neutralizing antibodies than Delta. The scientists then analyzed the blood of people who had received two doses of the Pfizer or AstraZeneca vaccine. Five months after vaccination, the antibodies in the blood were no longer capable of neutralizing Omicron. This loss of efficacy was also observed in individuals who had been infected with SARS-CoV-2 within the past 12 months. Administering a booster dose of the Pfizer vaccine or a single vaccine dose in previously infected individuals led to a significant increase in antibody levels that was sufficient to neutralize Omicron. Omicron is therefore much less sensitive to the anti-SARS-CoV-2 antibodies currently used in clinical practice or obtained after two vaccine doses. The study was published as a preprint on the bioRxiv website on December 15, 2021 and in Nature on Dec 23, 2021 Initial epidemiological studies demonstrate that the Omicron variant is more transmissible than the Delta variant. The Omicron variant's biological characteristics are still relatively unknown. It has more than 32 mutations in the spike protein compared with the first SARS-CoV-2 and was designated as a variant of concern by WHO on November 26, 2021. In South Africa, the Omicron variant replaced the other viruses within a few weeks and led to a sharp increase in the number of cases diagnosed. Analyses in various countries indicate that the doubling time for cases is approximately 2 to 4 days. Omicron has been detected in dozens of countries, including France and became dominant by the end of 2021.
  • 《Medicalxpress,12月27日,Scientists identify antibodies that can neutralize omicron》

    • 来源专题:COVID-19科研动态监测
    • 编译者:YUTING
    • 发布时间:2022-01-03
    • An international team of scientists have identified antibodies that neutralize omicron and other SARS-CoV-2 variants. These antibodies target areas of the virus spike protein that remain essentially unchanged as the viruses mutate. By identifying the targets of these "broadly neutralizing" antibodies on the spike protein, it might be possible to design vaccines and antibody treatments that will be effective against not only the omicron variant but other variants that may emerge in the future, said David Veesler, investigator with the Howard Hughes Medical Institute and associate professor of biochemistry at the University of Washington School of Medicine in Seattle. "This finding tells us that by focusing on antibodies that target these highly conserved sites on the spike protein, there is a way to overcome the virus' continual evolution," Veesler said. Veesler led the research project with Davide Corti of Humabs Biomed SA, Vir Biotechnology, in Switzerland. The study's findings were published Dec. 23 in the journal Nature. The lead authors of the study were Elisabetta Cameroni and Christian Saliba (Humabs), John E. Bowen (UW Biochesmistry) and Laura Rosen (Vir). The omicron variant has 37 mutations in the spike protein, which it uses to latch onto and invade cells. This is an unusually high number of mutations. It is thought that these changes explain in part why the variant has been able to spread so rapidly, to infect people who have been vaccinated and to reinfect those who have previously been infected. "The main questions we were trying to answer were: how has this constellation of mutations in the spike protein of the omicron variant affected its ability to bind to cells and to evade the immune system's antibody responses," Veesler said. [Veesler and his colleagues speculate that omicron's large number of mutations might have accumulated during a prolonged infection in someone with a weakened immune system or by the virus jumping from humans to an animal species and back again.] To assess the effect of these mutations, the researchers engineered a disabled, nonreplicating virus, called a pseudovirus, to produce spike proteins on its surface, as coronaviruses do. They then created pseudoviruses that had spike proteins with the omicron mutations and those found on the earliest variants identified in the pandemic.