One of the elements of the immune system that protects us against infections, B cells, continue to act against SARS-CoV-2 months after infection; however, according to a study published in « Science Immunology», The derived antibodies do not recognize the mutant variants from Brazil and South Africa.
The results provide information on the dynamics, durability, and functional properties of the human B-cell response to SARS-CoV-2 infection and have implications for the design of vaccines that preferentially stimulate protective B-cell responses.
The study analyzed the B cells and more than 1,000 different monoclonal antibodies from 8 patients with covid-19 and found that, contrary to the previous hypotheses, the protective responses of B cells to the protein spike of SARS-CoV-2 remain stable and continue to evolve over a period of 5 months, much longer than the initial period of active viral replication.
The research also observed that a large proportion of the neutralizing antibodies generated from these long-lived B cells did not efficiently recognize several emerging variants of SARS-CoV-2 from Brazil and South Africa.
Laura M. Walker’s team, from biotechnology Adimab LLC, profiled spike protein-specific B-cell and antibody responses in 8 patients with mild and severe COVID-19 over five months.
As documented so far, they observed a significant decrease in the levels of neutralizing antibodies in the blood over time; Nevertheless, spike protein-specific memory B cell levels remained stable or even increased over the same time period.
In addition, the researchers found that after 120 days, monoclonal antibodies isolated from these B cells underwent increased somatic hypermutation, binding affinity, and neutralizing potency, all signs of persistent B cell activity.
The authors conclude that rigorous monitoring of circulating SARS-CoV-2 variants is required to determine variability in these protein sites to establish how these mutations affect vaccine-induced immunity.