A new study published in the journal “Nature” on July 19 revealed the “tip of the iceberg” of asymptomatic infections. Mutations in the genes of certain immune system molecules on the surface of cells called HLA (human leukocyte antigen) are more likely to cause no symptoms after infection, the study found.
The study found that about 20% of people infected with the new crown did not show any symptoms after testing positive for the new crown.
Why are some people “asymptomatic” after being infected with the new crown? (pixabay)
The study included nearly 30,000 participants. The researchers tested the association of five HLA genotypes with the course of the new crown, and found that a genotype of HLA-B*15:01 was most closely associated with asymptomatic infection. People with these genetic mutations were eight times more likely to remain asymptomatic after infection than those who did not.
“This genetic association is due to pre-existing T cell immunity, and we found that T cells in samples from individuals with HLA-B*15:01 were immunodominant to other respiratory coronaviruses prior to COVID-19. The derived peptide has an immune response, so that it can also produce cross-immunity against the new coronavirus.” The researcher said.
T cells are immune cells that help the body recognize and remember proteins. They build memory for the immune system so that it can respond and make antibodies if it sees the pathogen again.
HLA is divided into type 1 and type 2. The first type is divided into HLA-A, HLA-B, HLA-C; the second type is divided into: HLA-DP, HLA-DQ, HLA-DR, there are tens of thousands of variations in these typing genes. “There are more than 50,000 HLA subtypes in the population, and HLA is the most polymorphic gene in the population.
virus (pixabay)
According to the data cited by the above-mentioned experts from their institutions, HLA-B*15:01 accounts for about 2% of the Chinese population. In fact, HLA is related to many autoimmune diseases, and similar reports have been published, but this time it is related to the new crown, so it has its value.
HLA molecules stick out from the surface of certain human white blood cells, as well as cells in many other tissues of the body, and deliver fragments of the protein to the immune system so it can recognize viruses when they encounter them again.
Jill Hollenbach (Jill Hollenbach), author of the study and a professor of neurology at the Weill Institute for Neuroscience at the University of California, San Francisco, said that after cells are infected with the new coronavirus, viral proteins are translated in cells, and some protein fragments will Delivered to the cell surface, the HLA molecules grab them and retain them, making them visible to T cells.
Although there is a strong association between the HLA-B*15:01 genotype and asymptomatic infection, the researchers said this still only accounts for 20% of the proportion of asymptomatic infections, so it is not the reason why people become asymptomatic infections. only explanation.
Why are some people “asymptomatic” after being infected with the new crown? (pixabay)
“No doubt there must be other important genetic and non-genetic factors that cause some people to be infected without symptoms, but we don’t know what those factors are yet,” Holenbach said.
Likewise, genetic changes may also be partly responsible for the long-term risk of contracting the new coronavirus. Another recently published preprint study that has not yet been peer-reviewed shows that individuals with certain changes in the gene for FOXP4, a protein active in the lungs and immune system, appear to be more likely to develop long-term COVID-19.
The study found that people with a mutation in the FOXP4 gene were about 60 percent more likely to develop COVID-19 than people without the mutation. This discovery provides research clues for the potential mechanism of the new crown.
2023-07-27 09:42:54
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