There are still many people who have never been infected with Covid-19. In some cases, despite close contact with infected people. How is that possible? First of all, immunity is very individual and varies from person to person. Several studies also provide information on this.
Study: Special gene variant protects against corona symptoms
In the USA, researchers have found an explanation for why some people only become infected with corona asymptomatically. Jill Hollenbach from the University of California in San Francisco and her team suspect that these people have a special variant of the genes that encode the “human leukocyte antigen” – HLA for short.
In the Study According to the researchers mdr.de discovered that people with the HLA-B15 mutation can produce messenger substances that help the so-called “killer T cells” to recognize Sars-CoV-2 even if the immune system has never had contact with the virus before. The T cells can then fight a protein building block in the virus that also occurs in a similar form in the common cold coronaviruses. This is why those affected are said to have cross-immunity mediated by HLA-B15.
For the study, Hollenbach and her team were able to access the data of around 30,000 bone marrow donors. Of these, 1,428 people had tested positive for Covid-19 at least once by April 2021 – i.e. before the corona vaccination was available. 136 people had remained symptom-free for at least two weeks despite a positive corona test.
In the group without symptoms, the researchers found the HLA-B15 mutation in around 20 percent, while in the group with symptoms only 9 percent carried the gene. The study therefore concludes that the immune system of people with the gene mutation can probably eliminate the viruses more quickly. According to mdr.de The mutation also seems to be able to compensate for known risk factors such as obesity, previous illnesses and old age.
According to Hollenbach and her team, the results of the study “have important implications for understanding early infection and the mechanisms underlying early viral defense.” Therefore, the study, which will be published on July 19, 2023 in the journal Nature published, will provide a basis for “refining vaccine development and therapeutic options in early disease”.
Corona study: Researchers find protein that protects against infection
Researchers from Australia have discovered a protein that could explain the corona immunity of some people. The group published their results on February 9, 2023 in PLOS Biology journal published. Genomics professor Greg Neely, Dr. Lipin Loo and Matthew Waller have discovered the protein LRRC15 (leucine-rich repeat-containing protein 15), which adheres to Sars-CoV-2 in the lungs like Velcro and thus incapacitates the virus. Specifically, LRRC15 docks onto the spike protein of Sars-CoV-2 and thus prevents other cells from being infected.
In their study, the researchers examined the lungs of people who had died from Covid-19 or other diseases. Particularly large amounts of the new protein were found in the lungs of patients with severe corona cases. The British The Guardian The researchers said that LRRC15 was not detectable in humans before a corona infection. Therefore, Greg Neely, Lipin Loo and Matthew Waller assume that the protein is part of a new immune barrier that protects against severe Covid-19 courses and activates the body’s immune response. Why did the patients die anyway? According to the researchers, LRRC15 production may have started too late or produced too small amounts to help.
A study from London supports the researchers’ theory. Blood tests showed higher levels of the protein in patients with a mild course of corona than in people with a severe course. The researchers from Australia now hope that new drugs can be developed based on LRRC15 that block viral infections.
Corona study: Some people are resistant to Corona
Other studies have also examined the immunity of some people. One of the most important findings: some people are simply resistant to the coronavirus. This was discovered by British researchers and published in a study in the journal Nature which was published in November 2021. T cells play a major role in this.
These are white blood cells that recognize foreign structures and can represent the acquired immune system. When examining 58 hospital employees, the research team led by Leo Swadling apparently found a connection between corona infections and T cells. Although these hospital employees have a high risk of infection, they did not become infected. 20 of the people had an increased level of T cells, and in 19 the researchers discovered an immune protein called IFI27.
Immune protein IFI27 as an important indicator of a corona infection
The immune protein IFI27 is said to indicate that the person in question has already had contact with the coronavirus. At least that is what the British researchers claim to have found out. They have the theory that in such a case an infection occurred, but was aborted by an immune reaction of the body. The researchers believe that a possible reason is a rapid fight against the virus by T cells. This means that Covid-19 cannot or hardly multiply in the body.
As a result, the test subjects avoided a corona infection because it was aborted. However, according to the researchers, the T cells could also indicate a corona infection other than Covid-19. This could, for example, be a cold that occurs seasonally.
Corona resistance is linked to T cells
In January 2022 Another study appeared in Naturewhich deals with the exciting question of why some people seem to be immune to corona. Researchers at Imperial College London confirmed the importance of T cells – and also found evidence for the effectiveness of cross-immunity. “Our results suggest that cross-reactive memory T cells protect people without prior contact with SARS-CoV-2 from such an infection,” the scientists summarize their study. For this, they examined 52 people who had proven contact with the coronavirus, but only half of whom had been infected. Blood samples revealed interesting findings:
“Our study provides the clearest evidence to date that T cells caused by cold coronaviruses have a protective function against SARS-CoV-2 infection,” explained Ajit Lalvani, senior author of the study: “These T cells offer protection by attacking proteins inside the virus and not the spike protein on the virus’s surface.” After more than two years of the coronavirus pandemic, this means that anyone who has never been infected with coronavirus is likely to have a high level of cross-reactive T cells, according to the study. At the same time, these ensure that the risk of suffering a serious course of the disease is reduced. The findings of the study are of great value in the further development of vaccines. And they show that anyone who has not yet been infected with the coronavirus probably has a good chance of staying that way.
No corona infection: Blood group can also play a role
French scientists showed in a studythat blood type can also have an influence on infection with Sars-CoV-2. According to this, the risk of infection increases if the blood types of the people involved match – as is the case with a blood donation. If the sick person and a healthy person both have the same blood type, the probability of infection increases. This is also the case if the first infected person has blood type 0 and the infected person has blood type A. In the study, however, the probability of infection decreased if the infected person has a blood type that the other person cannot tolerate when donating blood. This could also explain why people with blood type 0 have the lowest risk of infection. This is because blood type 0 is compatible with all other blood types, but can only accept donations of its own blood type.
Fighting Corona: A healthy lifestyle is also important
In addition to hereditary conditions, there are other ways to reduce the risk of corona infection. These include, for example, avoiding large crowds, using a face mask and the usual procedures that are good for your health. We have summarized six tips here that will strengthen your immune system – including against viral diseases.
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