Study finds viruses may have ‘eyes and ears’ on us

Washington: New research suggests that viruses use information from their environment to stay inside their hosts and “decide” when to multiply, explode, and kill host cells. Viruses exploit their ability to monitor their environment for profit. But in the future, “it could be exploited to their detriment,” says one of the authors.

A virus’ ability to sense its environment, including elements produced by the host, “adds an additional layer of complexity to virus-host interactions,” says a professor of biological sciences and senior author of the new paper. says Ivan Erill. Now the virus is exploiting that ability to profit. But in the future, “it could be exploited to their detriment,” he says.

The new research focused on bacteriophages – viruses that infect bacteria, often simply called phages. The phages in this study can only infect a host if the bacterial cell has specialized appendages called fimbriae and flagella, which help the bacteria move and mate. produces a protein called CtrA that controls when to produce A new paper shows that many appendage-dependent phages have patterns of DNA that the CtrA protein can bind to, called binding sites. Phages with binding sites for proteins produced by the host are rare, Ellil says.

Even more surprisingly, Erill and the original author of the paper, Elia Mascolo, both have PhDs. Through detailed genomic analysis, students in Erill’s lab discovered that these binding sites are not unique to a single phage, or to a single phage group. Many different types of phage had her CtrA-binding site, but they all needed to have fimbriae or flagella to infect the host. It couldn’t be a coincidence, they decided.

The ability to monitor CtrA levels “has been invented many times over the course of evolution by different phages that infect different bacteria,” says Erill. When distantly related species exhibit similar traits, it is called convergent evolution, indicating that the trait is certainly useful.

Another wrinkle in the story: The first phage for which the researchers identified a CtrA-binding site infects a specific group of bacteria called Caulobacteria.

Aurobacteria are a particularly well-studied group of bacteria because they exist in two forms. There are two forms: a “flock” form that swims freely, and a “stem” form that attaches to the surface. Flocks have cilia/flagellates, stems do not. In these bacteria, CtrA also regulates the cell cycle, determining whether cells divide equally into two of the same cell type or divide asymmetrically to generate one swarmer cell and one stalk cell. increase.

Since phages can only infect swarm cells, it is a phage’s greatest concern to break out of its host only when there are a large number of swarm cells it can infect. Caulobacteria generally live in nutrient-poor environments and are very widespread. “But when they find a good pocket of microhabitat, they become stalked cells and proliferate,” says Erill, eventually producing large numbers of swarm cells.

So, “we hypothesize that phages monitor CtrA levels that go up and down during the cell’s life cycle to know when a swarmer cell becomes a stalk cell and a swarmer factory,” says Erill. says Mr. At that point they burst the cell. Because there are a lot of infected Swarmers nearby. “

Unfortunately, the method of proving this hypothesis is labor-intensive and very difficult, so it is not included in this latest paper, but Eryl and colleagues hope to address the issue in the future. The research team finds no other plausible explanation for the multiplication of CtrA-binding sites on so many different phages that require fimbriae/flagellates to infect the host. Even more interesting is the effect on viruses that infect other organisms and even humans.

“Everything we know about phages, the evolutionary strategies they have developed, have been shown to translate into viruses that infect plants and animals,” he says. So if phages are listening to their hosts, viruses that affect humans must be doing the same.”

Several other examples of phages monitoring their environment in interesting ways have been documented, but none involving so many different phages employing the same strategy against so many bacterial hosts. there is no.

The new study “is the first extensive demonstration that phages are listening to what’s going on inside a cell, in this case, cell development,” says Eryl. Inside, he predicts. Already members of his lab have begun searching for receptors for other bacterial regulatory molecules within the phage and have found them.

The key takeaway from this study is that “viruses use cellular information to make decisions,” Eryl says. Evolution finds it and takes advantage of it. “

For example, an animal virus may want to know what types of tissues it resides in or how robust the host’s immune response to infection is to optimize strategies for survival and replication. It may be unnerving to think about all the information a virus might collect and use to make us sick, but these discoveries also pave the way for new treatments.

“If you’re developing an antiviral drug and you know that the virus is listening to certain signals, you might be able to trick the virus,” says Eril. ahead. For now, “we’re just starting to realize how actively the virus is watching us, watching what’s going on around us and making decisions based on that.” he says Erill. “It’s fascinating.”