A new sudy revealed that protective B cell responses to the SARS-CoV-2 spike protein remain stable and continue to evolve over a 5-month period post-infection. This is contrary to the previous hypotheses made by some researchers.

For the study, the researchers examined B cells and more than 1,000 different monoclonal antibodies from eight patients with Covid-19.

Their findings suggested that B cells protect from Covid-19 months after the infection. However, a large proportion of the neutralizing antibodies generated from these long-lasting B cells did not efficiently recognize various emerging SARS-CoV-2 variants from Brazil and South Africa.

The authors believe that their study will help other scientists to design future Covid-19 vaccines that work to prevent viral evolution. The vaccines should also stimulate better neutralizing antibody and B cell responses against emerging SARS-CoV-2 variants.

In the study, Mrunal Sakharkar and the team profiled spike protein-specific B cell and antibody responses in eight patients with mild and severe Covid-19 over five months.

They found a significant decline in neutralizing antibody levels in the blood over time. However, levels of spike protein-specific memory B cells remained stable or even increased during the same time frame.

Over the course of 120 days, monoclonal antibodies isolated from these B cells underwent increased somatic hypermutation, binding affinity, and neutralization potency - all signs of persistent B cell activity.

Notably, a large proportion of the neutralizing antibody response did not efficiently recognize emerging SARS-CoV-2 variants from Brazil and South Africa. These mutations harbour amino acid positions 417 and 484 of the spike protein.

The authors suggested careful monitoring of circulating SARS-CoV-2 variants so as to determine how these mutations impact vaccine-induced immunity.

The findings of the study were published in the journal American Association for Advancement of Science (AAAS).

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