Nature: The body's immune system is also coping with evolution in the face of the new coronavirus mutation

For patients infected with the new coronavirus, neutral antibodies produced by the immune system are produced to protect them from infection.
but how long does the immune system's antibody activity against SARS-CoV-2 last? Will the quantity and quality of B cells decline? Can you identify new coronavirus that responds to mutations? These are still unknown.
recently, a team of researchers from Rockefeller University and mount Sinai's Icahn School of Medicine published a study in Nature entitled Evolution of antibody immunity to SARS-CoV-2, which found that patients were infected with SARS-CoV-2. After 2 6.2 months, although the body fluid and active antibodies significantly decreased, but the memory B cells in the evolution of somogenic cell super-mutation, expressed with enhanced effectiveness and resistance to RBD mutation antibodies, solibo immunity has been developing.
To study long-term antibody immunity in patients infected with SARS-CoV-2, the researchers analyzed the levels of meso-antibodies and memory B cell characteristics in 87 COVID-19 patients at 1.3 and 6.2 months after infection.
ase-linked immunosorption (ELISA) and automatic serological assays found that between 1.3 and 6.2 months, the anti-RBD (new coronavirus pyrethroid protein binding domain) and anti-N (nuclear protein) antibodies in the blood decreased significantly, and the decline of each antibody was inversely inversely related to the initial antibody level.
The use of HIV-1 prosthetic viruses containing SARS-CoV-2 prickly proteins measured plasma and activity was found to have a 5-fold decrease in the moderate antibody titration of the new coronavirus at 6.2 months compared to 1.3 months, indicating that 6 months after SARS-CoV-2 infection, there was a significant decrease in the number of moderately active antibodies in the patient's body, but were still detectable.
Memory B cells are differentiated by B cells in the immune system, the antigen has a specific recognition ability, when antigen secondary infection of the body, memory cells can directly multiply, differentiate to produce plasma cells, and produce antibodies, binding to antigens.
analysis of SARS-CoV-2 memory B cells in patients found a small but significant increase in memory B cells of IgG antibodies expressing anti-RBD in the memory B cell population between 1.3 and 6.2 months.
In addition, the researchers found that memory B cells at 1.3 and 6.2 months showed updates in monoclonal antibody species and the evolution of antibody sequences, suggesting that the immune system continued to optimize its antibody immune response to the new coronavirus between 1.3 and 6.2 months after infection.
evaluated the re reactivity of 122 representative antibodies to RBD at these two points in time and found that 115 of them were able to bind to RBD and that the EC50 (semi-maximum effect concentration) of the antibody increased significantly at 6.2 months.
how resistant are these antibodies to virus-mutant strains? The researchers measured their binding effects to the wild TYPE RBD and mutant RBD of SARS-CoV-2 and found that 83% of the antibody clones that occurred at both points in time were cloned with the mutant R at 6.2 months. The overall binding of BD increased, and the binding increase was most significant in E484 (Brazilian and South African mutation position), Q493, N439, N440 and R346 RBD mutation amino acid positions.
analysis of the meso-wide range of antibodies that bind to the mutant RBD found that, in addition to having a stronger melision force, the antibodies expressed by evolutionary memory B cells also had a higher median breadth, and some antibodies were able to mediate more than one viral variant.
Finally, the researchers analyzed that the evolution of antibodies may be through antigens in the form of immunopsytotic cells retained in the form of a filter tree protrusion cell surface for a long time, so that the B cells at the center of the birth of sombo cells super-mutation and constant selection occur, the human tissue residual low-level viral proteins may also be as antigens to further promote the evolution of antibodies.
references: s1. Evolution of antibody immunity to SARS-CoV-2