Many different types of cells are susceptible to infection by viruses, and these infected cells typically have the ability to mount an immediate immune response. Bacterial cells attacked by viruses have no method to summon outside support from the immune system, but they may mount defense mechanisms against the virus. Bacteriophages, viruses that infect bacteria, have also developed strategies to escape cellular-level immunity. Researchers have discovered more about a previously unknown chemical and an innovative technique that viruses utilize to subvert bacterial defenses. These results, published in Nature, may elucidate the cellular mechanisms that regulate the immune response to viral infection in humans.
It is possible for bacteriophages (or phages) to infect bacteria by injecting their viral genomes into the cells of their prey. As soon as that occurs, the bacterial cell is essentially turned into a factory where additional virus particles are produced and released. An infected bacterial cell will eventually perish.
The TIR molecule in bacteria may identify phage infection. When this happens, the immune system responds through TIR. Upon investigation, TIR was discovered to be a part of the immune systems of plants, animals, and microorganisms.
To date, scientists have unveiled the means through which phages avoid TIR’s deleterious effects. Tad1 is a protein found in certain phages; it may block the effects of TIR by binding to the receptor. TIR’s triggered signal may be caught by Tad1 practically instantly.
Professor Rotem Sorek of the Weizmann Institute of Science, who led the research, said, “It was as though the protein immediately absorbed the molecule, without allowing the immune system have even a glance of it.” No other virus is known to have developed such an immune-evasion mechanism.
Since the phage had successfully acquired the chemical signal, the scientists planned to use crystallography to determine its structure. Sorek said that the researchers had “help from the phage” in determining the identity of the “mystery immunological molecule.”
According to Sorek’s findings, “we found a novel mechanism that viruses may suppress immune systems that depend on signaling molecules.” These immune systems are found in the cells of animals and humans as well as microorganisms.
Studying phages and how they have developed to adapt to bacterial defense systems may provide light on the viruses that impact humans.
To that end, “we will not be astonished if viruses that infect human body employ the identical mechanism as the Tad1 we identified in phages,” Sorek said.
Weizmann Institute of Science, Nature, etc.
