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How long does the coronavirus vaccine work?
How long does the coronavirus vaccine work? Science published an article reveals: may be affected by differences in age and B cell memory in tissues.
Vaccines work because there is a kind of immune cell in our body-memory B cells. When the original memory B cells are activated by an antigen for the first time, they will proliferate in a large amount.
Most of them differentiate into plasma cells (effector B cells) and produce antibodies to clear the infection, while the rest differentiate into memory cells. Memory cells can usually survive for several years or even life.
So, at the moment when the COVID-19 epidemic is spreading, how long will the COVID-19 vaccine be able to manage? How can I get sick after being vaccinated?
Recently, the Scott D. Boyd research group of Stanford University in the United States published the latest progress in the world-class academic journal “Science”, entitled “Shared B cell memory to coronaviruses and other pathogens varies in human age groups and tissues”, for these issues Provided for reference.
Researchers have found that the B-cell memory shared by coronaviruses and other pathogens differs in human age groups and tissues.
In order to study the changes of cellular immune memory in human life and across tissues, the researchers studied the specific immunoglobulin heavy chains (IGH) of 6 common pathogens, as well as volunteers who have not been exposed to Ebola virus and new coronavirus virus. Characterized.
The study analyzed a total of 12 cord blood (CB) samples, 93 blood samples from 51 children aged 1 to 3 (18 years old), 114 blood samples from healthy adults aged 17 to 87 (18 years old), and 8 deceased organ donations Convergent antigen-specific antibody genes in blood, lymph node, and spleen samples of patients.
Frequency, category switching and SHM of child and adult disease-specific convergent clones
B cell clones are generally divided into three categories:
(1) naive clones containing only unmutated IgM or IgD (unmutM/D);
(2) IgM/D with antigens, with a median SHM over 1% and no class switching members ( mutM/D);
(3) Antigenic clones (CS) with class switching members.
The results of the study showed that the frequency of IGH fusion was the lowest in cord blood samples. The fusion clones of children and adults were mostly mutM/D or CS, while in adult blood samples, Haemophilus influenzae type b (Hib) and Neisseria meningitidis Fusion clones of bacteria (NM) and respiratory syncytial virus (RSV) are mainly mutM/D clones, while pneumococcal (PP), tetanus toxoid (TT) and influenza clones are mainly CS clones. But the strange thing is that the frequency of Hib, PP, TT and RSV CS fusion clones in children is higher than that in adults, and mutant IgM or IgD are also found in these clones. The frequency of fusion clones in the blood of children is not significantly related to the time of vaccination.
Distribution of fusion B cell clones in tissues
In the analysis of blood, spleen, mediastinal lymph node (MDLN) and mesenteric lymph node (MSLN) of 8 adult dead organ donors, the frequency of fusion clones of Hib, NM, PP, TT, RSV and influenza in adult lymph nodes and spleen was higher than blood. Adult lymph nodes and children’s blood have more confluent clones, showing the different distribution of these clones in children and adults.
Previous reports suggested that specific B cells against bacterial capsular polysaccharides are enriched in the spleen, and patients with splenectomy are susceptible to infection by these bacteria. However, existing observational data show that the convergent clone frequency of Hib, NM and PP in lymph nodes is similar to or higher than that of spleen. The number of B cells in human lymph nodes is greater than that in the spleen, which indicates that the spleen is not the only savings point for these clones.
Fusion clone of SARS-CoV-2 and EBOV
In samples that did not suffer from COVID-19 disease or before the disease, the researchers found that SARS-CoV-2 fusion clones were more common in children’s blood. 37 out of 51 children had SHM with or without CS, indicating previous antigen experience. The frequency of SARS-CoV2 convergent clones in blood and lymph tissues of adults is lower than that of children, and there are few examples of CS. This shows that compared with adults, children have a higher frequency of fused B cell clones in their blood.
In conclusion, this article reveals that B cell memory differs from pathogen to pathogen. The specific cloning of polysaccharide antigens is not limited to the spleen. Adults have higher cloning frequency and category switching in lymphoid tissues than blood, while children’s blood has abundant category switching fusion clones. The results of the study emphasize the importance of early childhood B cell clonal expansion and cross-reactivity in the future response to new pathogens.
(source:internet, reference only)