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,” 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 biotech 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 period of time.
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.