A recent American study found that viruses use information from their environment to decide when to stay quietly inside their host and when to reproduce, as if they are watching and hearing the environment around them.
This finding, that viruses have the ability to monitor their environment, may play a role in the development of antiviral drugs.
The study was conducted by researchers from the University of Maryland, Baltimore County, and was published in the journal " Frontiers in Microbiology" last August, and transmitted by the " Eurek Alert " website.
The researchers found that viruses use information from their environment to make a decision about the following risk: do they sit quietly inside the host cell or multiply and explode, killing the host cell.
Viruses that infect bacteria
For his part, Evan Earl, professor of biological sciences and senior author of the study, explained that the virus's ability to sense its environment, including elements produced by its host, adds another layer of complexity to the viral interaction with the host. Today, viruses are exploiting this ability to their advantage. But in the future, says Earl, "we can take advantage of that, to damage the viruses."
The new study focused on 'bacteriophages', which are viruses that infect bacteria.
Phages, according to the study, can only infect their hosts when bacterial cells have special appendages called filaments and flagella, which help bacteria move and mate.
The bacteria produce a protein called CtrA that controls when polyps form. The new paper shows that many phages have shapes in their DNA where CTRA can cleave, called binding sites.
Explosion
The researchers studied a type of bacteria called "Caulobacterales". These bacteria exist in two forms: a swarmer that swims freely, and a stalked form that sticks to the surface.
Because phages can only infect swarm cells, it is in their interest to explode (reproduce in large numbers) outside their host when there are many swarm cells available to infect.
So the researchers hypothesized that phages monitor CTRA levels, which rise and fall during the life cycle of cells, to see when a swarm cell becomes a stem cell and becomes a swarm factory. "At that point, the viruses will blow the cell, because there will be many swarms close to infection," says Earl.
Unfortunately, the method of proving this hypothesis requires a very extensive and difficult process, so this was not part of this latest paper although Earl and colleagues hope to address this question in the future.
However, the research team sees no other plausible explanation for the multiplication of CTRA-binding sites on many different phages, all of which require flagella to infect their hosts. Even more interesting, they noted, are the effects of viruses that infect other organisms, such as humans.
New treatment methods to deceive the virus
A key finding from this research, Earl says, is that "a virus uses cellular intelligence to make decisions, and if it occurs in bacteria, it is almost certain that it occurs in plants and animals."
For example, to improve its strategy for survival and reproduction, an animal virus may want to know what type of tissue it is in or how strong the host's immune response to infection is. While it can be disconcerting to think about the information viruses can collect and possibly use to make us sicker, these discoveries also open up avenues for new treatments.
"If you're developing an antiviral drug, and you know the virus is listening for a certain signal, you can probably fool the virus," says Earl.
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