Study identifies antibody that protects against many variants

The researchers selected the two antibodies that were most effective at protecting mice from disease and tested them against a panel of viral variants.

Researchers at Washington University School of Medicine in St Louis have identified an antibody that is highly protective at low doses against a wide range of variants of SARS-CoV-2, the coronavirus that causes Covid-19.

Moreover, the 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 study has been published in the journal Immunity. The researchers say the findings could be a step towards developing new antibody-based therapies that are less likely to lose their potency as the virus mutates.

SARS-CoV-2, the virus that causes Covid-19, uses a protein called spike to attach to and invade cells in the body’s respiratory tract.

Antibodies that prevent the spike from attaching to cells neutralise the virus and prevent disease. Many variants have acquired mutations in their spike genes that allow them to evade some antibodies generated against the original strain. This has undermined the effectiveness of antibody-based therapeutics.

To 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). Then, they extracted antibody-producing cells and obtained 43 antibodies from them that recognise the RBD.

The researchers selected the two antibodies that were most effective at protecting mice from disease and tested them against a panel of viral variants.

The 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. One antibody, SARS2-38, easily neutralised all the variants.

Moreover, 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.

Source: Washington University School of Medicine in St Louis

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