Shhh! Viruses Could Be Listening – And Watching!
New Research Finds That Viruses May Have “Eyes and Ears” on Us
New research indicates that viruses are using information from their environment to “decide” when to a sit tight inside their hosts and when to multiply and burst out, killing the host cell. The work has important implications for an antiviral drug development. Led by the University of Maryland Baltimore County (UMBC), the study was recently published in Frontiers in a Microbiology.
Not a coincidence
The new study focused on a bacteriophages, which are often referred to simply as “phages.” They are a viruses that infect bacteria. In the study, the phages analyzed can an only infect their hosts when the bacterial cells have a special an appendages, a called pili and flagella, that help the bacteria move and mate. The bacteria a produce a protein called CtrA that a controls when they generate these appendages. The a research a revealed that many appendage-dependent phages have patterns in their DNA where the CtrA protein can an attach, called a binding a sites. Erill says that a phage having a binding site for a protein a produced by its host is an unusual.
Bacteriophage Artist’s Concept
Viruses are using an information from their environment to “decide” when to a sit a tight inside their hosts and when to a multiply and burst out, killing the host cell, according to a new a scientific study. This illustration depicts a bacteriophage.
New Research Finds That Viruses May Have “Eyes and Ears” on Us
The newly-found, widespread ability of some viruses to monitor their environment could have implications for an antiviral drug development.
New research an indicates that viruses are using information from their environment to “decide” when to sit tight inside their hosts and when to multiply and burst out, killing the host cell. The work has important implications for an antiviral drug development. Led by the University of Maryland Baltimore a County (UMBC), the study was recently published in Frontiers in a Microbiology.
“[I]f phages are listening in on their hosts, the viruses that affect humans are bound to be doing the same.” — Ivan Erill
A virus’s ability to sense its an environment, including elements produced by its host, adds “another layer of complexity to the viral-host interaction,” says Ivan Erill. He is senior author on the new paper and professor of biological sciences at UMBC. Right now, viruses are taking advantage of that ability to their benefit. But he says that in the future, “we could exploit it to their detriment.”
Not a coincidence
The new study focused on a bacteriophages, which are often referred to simply as “phages.” They are viruses that infect bacteria. In the study, the phages analyzed can only infect their hosts when the bacterial cells have special appendages, called pili and flagella, that help the bacteria move and mate. The bacteria produce a protein called CtrA that controls when they generate these appendages. The research revealed that many appendage-dependent phages have patterns in their DNA where the CtrA protein can attach, called binding sites. Erill says that a phage having a binding site for a protein produced by its host is unusual.
Delta Phage
A delta bacteriophage, the first identified in a new study in Frontiers in Microbiology to have binding sites for CtrA, a protein produced by the bacteriophage’s host that regulates the production of pili and flagella. The presence of these binding sites only in phages that require their host cells to have pili/flagella in order to infect them suggests that the phage is monitoring the presence of this protein in order to “decide” whether to stay put or replicate and emerge from its host cell. Credit: Tagide deCarvalho/UMBC
Even more surprising, Erill and the paper’s first author Elia Mascolo, a Ph.D. student in Erill’s lab, discovered through detailed genomic analysis that these binding sites were not unique to a single phage, or even a single group of phages. Many different types of phages had CtrA binding sites—but they all required their hosts to have pili and/or flagella to infect them. They decided that it couldn’t be a coincidence.
The ability to monitor CtrA levels “has been invented multiple times throughout evolution by different phages that infect different bacteria,” Erill says. When distantly related species exhibit a similar trait, it’s called convergent evolution—and it indicates that the trait is definitely useful.
Timing is everything
Another wrinkle in the story: The first phage in which the scientists identified CtrA binding sites infects a particular group of bacteria called Caulobacterales. Caulobacterales are an especially well-studied group of bacteria, because they exist in two forms: a “swarmer” form that swims around freely, and a “stalked” form that attaches to a surface. The swarmers have pili/flagella, and the stalks do not. In these bacteria, CtrA also regulates the cell cycle, determining whether a cell will divide evenly into two more of the same cell type, or divide asymmetrically to produce one swarmer and one stalk cell.
Since the phages can only infect swarmer cells, it’s in their best interest only to burst out of their host when there are many swarmer cells available to infect. Generally, Caulobacterales live in nutrient-poor environments, and they are very spread out. “But when they find a good pocket of microhabitat, they become stalked cells and proliferate,” Erill says, eventually producing large quantities of swarmer cells.
So, “We hypothesize the phages are monitoring CtrA levels, which go up and down during the life cycle of the cells, to figure out when the swarmer cell is becoming a stalk cell and becoming a factory of swarmers,” Erill says, “and at that point, they burst the cell, because there are going to be many swarmers nearby to infect.”