Dubai, United Arab Emirates (CNN) — There are many factors that may determine how people recover after contracting the “Covid-19” virus, including the viral dose to which they were exposed, the place where the virus entered the body, nose, mouth or eyes, their age and basic health, and the genetic characteristics of the virus strain that they were infected with.
And new research explores another dimension in the mystery of how people are susceptible to this infection: genes.
A study published in the medical journal Nature on Wednesday shows that people who carry a common change in genes that code for certain immune system molecules on the surface of cells known as human leukocyte antigens were more likely to be infected with the “Covid-19” virus without any symptoms.
Another study, which was recently posted online as a pre-print before peer review and publication, found that individuals who had certain changes in genes near FOXP4, which codes for a protein active in the lungs and immune system, appeared to be more likely to develop “long-term COVID-19.”
HLAs are used to determine the compatibility of organs with patients who need transplants, and these molecules protrude from the surface of some white blood cells, as well as cells in many other tissues of the body.
Study author Dr. Jill Hollenbach, a professor of neuroscience at the University of California at Weill Neurosciences in San Francisco, explained that the job of HLA molecules is to present parts of proteins to the immune system, so that it can recognize them if they are encountered again.
In a cell that has swallowed the virus that causes “Covid-19”, some of this virus is degraded in the cell, and some parts of the protein migrate to the surface, where they are picked up by human leukocyte antigen molecules so that T cells can see them.
T cells are immune cells that help the body recognize and remember proteins. They build a memory for the immune system so it can respond if it sees the pathogen again.
There are three general groups of HLAs, and within these groups, there are hundreds of variations of these molecules.
Hollenbach noted that each molecule would specifically look for certain types of protein fragments and display them in a specific way so that T cells could see them and learn how to make antibodies against them.
Genes may also help explain why some people develop symptoms that persist and develop into “long Covid”.
For more than three years, an international group of scientists has been searching for genes that may be associated with severe Covid-19 infection.
The researchers narrowed down data from 24 studies involving nearly 6,500 people and compared it to more than a million others who were in the comparison group.
The investigation into “Long-Covid” is a by-product of that effort, led by scientists from the Karolinska Institutet in Stockholm, Sweden.
And by analyzing 11 of these studies, which involved sequencing all genes in a person’s body, and then comparing the genomes of large numbers of people, he showed that those who developed long-term Covid most likely shared DNA around a gene called FOXP4 that appears to be linked to the immune response in the cells of the small alveoli of the lungs. These cells also seem to help repair damage in the lungs.
“This particular genetic variant is interesting because it provides some insights into some of the underlying mechanisms associated with long-term COVID-19 and indicates a genetic predisposition. However, it cannot be relied upon alone to identify individuals at risk,” said Dr. Hugo Zeberg, lead study author and an evolutionary geneticist at Karolinska.
Zeberg added that genes are likely only one part of the reasons that lead to the development of “long Covid”, and there are likely to be many genes involved.
2023-07-21 11:38:13
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