Researchers have identified an antibody that is highly protective at low doses against a wide range of variants of the SARS-CoV-2 virus which causes COVID-19.
The findings, posted as a pre-proof in the journal Immunity, could help develop new antibody-based therapies that are less likely to lose their potency as the virus mutates.
바카라 웹사이트The new antibody attaches to a part of the virus that differs little across the variants, meaning that it is unlikely for resistance to arise at this spot, the researchers said.
바카라 웹사이트"Current antibodies may work against some but not all variants," said study senior author Michael S Diamond, a professor at Washington University School of Medicine in St Louis, US.
바카라 웹사이트"The virus will likely continue to evolve over time and space. Having broadly neutralising, effective antibodies that work individually and can be paired to make new combinations will likely prevent resistance," Diamond said.
바카라 웹사이트The SARS-CoV-2 virus uses a protein called spike to attach to and invade cells in the body's respiratory tract.
바카라 웹사이트Antibodies that prevent the spike protein from attaching to cells neutralise the virus and prevent disease.
바카라 웹사이트Many variants have acquired mutations in their spike genes that allow them to evade some antibodies generated against the original strain, undermining the effectiveness of antibody-based therapeutics.
바카라 웹사이트To find neutralising antibodies that work against a wide range of variants, the researchers immunised mice with a key part of the spike protein known as the receptor-binding domain (RBD).
바카라 웹사이트They then extracted antibody-producing cells and obtained 43 antibodies from them that recognise RBD.
바카라 웹사이트The team screened the 43 antibodies by measuring how well they prevented the original variant of SARS-CoV-2, that emerged in 2019, from infecting cells in a dish.
바카라 웹사이트Nine of the most potent neutralising antibodies were then tested in mice to see whether they could protect animals infected with the original virus from disease.
바카라 웹사이트Multiple antibodies passed both tests, with varying degrees of potency, according to the researchers.
바카라 웹사이트They selected the two antibodies that were most effective at protecting mice from disease and tested them against a panel of viral variants.
바카라 웹사이트The panel comprised viruses with spike proteins representing all four variants of concern -- Alpha, Beta, Gamma and Delta -- two variants of interest (Kappa and Iota), and several unnamed variants that are being monitored as potential threats.
바카라 웹사이트The researchers found that one antibody, SARS2-38, easily neutralised all the variants, a humanised version of SARS2-38 protected mice against disease caused by two variants: Kappa and a virus containing the spike protein from the Beta variant, they said.
바카라 웹사이트The Beta variant is notoriously resistant to antibodies, so its inability to resist SARS2-38 is particularly remarkable, the researchers noted.
바카라 웹사이트Further experiments pinpointed the precise spot on the spike protein recognised by the antibody, and identified two mutations at that spot that could, in principle, prevent the antibody from working.
바카라 웹사이트However, these mutations are rare in the real world, the researchers said.
바카라 웹사이트They searched a database of nearly 800,000 SARS-CoV-2 sequences and found escape mutations in only 0.04 per cent of them.
바카라 웹사이트"This antibody is both highly neutralising (meaning it works very well at low concentrations) and broadly neutralising (meaning it works against all variants)," said Diamond.
바카라 웹사이트"That's an unusual and very desirable combination for an antibody. Also, it binds to a unique spot on the spike protein that isn't targeted by other antibodies under development. That's great for combination therapy," the scientist explained.
바카라 웹사이트The researchers said this antibody can be combined with another one that binds somewhere else to create a combination therapy that would be very difficult for the virus to resist.
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