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Immune defenses themselves open "doors" to coronavirus
Last reviewed: 02.07.2025

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It turns out that the immune protein promotes the formation of multiple molecular “doors” in the cells of the mucous tissue for the entry of the coronavirus.
The SARS-CoV-2 coronavirus pathogen enters the cell using its own protein component S: it covers the fatty layer of the coronavirus. This protein interacts with the ACE2 receptor, a component of many cellular structures of the human body, known as angiotensin-converting enzyme. One of the functional areas of this receptor is the control of blood pressure. However, the coronavirus was able to benefit from it: after the formation of a connection between the viral S protein and ACE2, the cell membrane is deformed, and the virus has the opportunity to dive inside it. Of course, other protein components of the coronavirus, which are in its surface layer together with the S protein, also make their “contribution”. However, the leading role still belongs to the above-mentioned S protein and the ACE2 receptor.
It turns out that the coronavirus pathogen will more easily penetrate into those cells that have a greater number of ACE2 enzyme receptors. Scientists from the Max Delbrück Center for Molecular Medicine, as well as the Charité Clinical Center, the Free University of Berlin and other research centers, have noticed that the appearance of a greater number of ACE2 protein components on the surface of cells is due to increased activity of the immune defense. When the virus enters the body, immune cells begin to produce γ-interferon. This is the main signaling protein that activates the work of macrophages and accelerates the release of toxins.
It was found that under the influence of γ-interferon, the cells of the mucous tissue produce a greater number of enzyme receptors. Thus, thanks to the immune protein, the virus manages to penetrate the cells without problems. Scientists conducted a series of studies with an intestinal organoid - that is, with an intestinal microscopic copy formed by stem cells folded into a three-dimensional structure. The intestine was chosen as one of the organs that is affected by coronavirus infection along with the respiratory system.
When γ-interferon was added to the intestinal organoid, the gene encoding the enzyme receptor was stimulated inside the cells of the mucous tissue, which in turn increased. When the coronavirus pathogen was added to the organoid, more coronavirus RNA was found inside the cells after γ-interferon entered.
Scientists admit that the severe and prolonged course of COVID-19 may be associated with the activity of γ-interferon. However, for now this is just an assumption that requires detailed clinical studies - in particular, on the real intestine inside the body. If the experts' guesses are confirmed, the next step will be the development of a method to prevent interferon "support" from the immune defense.
The information is published in the public domain on the pages of the scientific journal EMBO Molecular Medicine.