Immune Cell Response to COVID-19 Evolve in Few Months
Date: January 20, 2021
- The COVID-19 virus has infected 78 million individuals.
- The COVID-19 virus is responsible for more than 1.7 million deaths.
- Infection is associated with development of varying levels of antibodies.
- The antibodies produced may come with neutralizing activity that can protect against infection in animal studies.
- Antibody levels decrease with time.
- During re-infection, memory B cells are called upon to produce antibodies.
- However, the nature and quality of the memory B cells has not been examined.
- Researchers reveal the humoral memory response of individuals assessed at 1.3 and 6.2 months after infection.
- Humoral immune response occurs when antibodies produced by B cells cause the destruction of extracellular microorganisms and prevent the spread of intracellular infections.
- Number of individuals in the study: 87
- Finding 1: IgM antibody concentration decrease significantly.
- Finding 2: IgG anti-SARS-CoV-2 spike protein receptor binding domain antibody decrease significantly.
- Finding 3: IgA antibody was less affected.
- Finding 4: Neutralizing activity in plasma decreases 5 times in pseudo-type virus assays.
- Finding 5: The number of receptor binding domain specific memory B cells remains unchanged.
- Memory B cells display clonal turnover after 6.2 months.
- The antibodies express by these memory B cells have greater somatic hypermutation, increased potency and resistance to receptor binding domain mutations.
- Somatic hypermutation is a high frequency alterations of a genes that affects the structure of antibody, thereby enabling the selection of B cells producing high-affinity antibodies.
- Intestinal biopsies obtained from asymptomatic individuals 4 months after the onset of COVID-19 disease revealed persistence of SARS-CoV-2 nucleic acids and immunoreactivity in the small bowel of 7 out of 14 volunteers.
- Researchers conclude that the memory B cell response to COVID-19 virus evolves between 1.3 and 6.2 months after infection.
Gaebler, C., Wang, Z., Lorenzi, J.C.C. et al. Evolution of antibody immunity to SARS-CoV-2. Nature (2021). https://doi.org/10.1038/s41586-021-03207-w https://www.ncbi.nlm.nih.gov/books/NBK10752/  https://www.sciencedirect.com/topics/immunology-and-microbiology/somatic-hypermutation
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