Healthcare (Commonwealth Union) – Researchers have discovered the way “pirate phages” commandeer other viruses to infiltrate bacteria, transferring new genetic material capable of carrying dangerous traits.
Scientists from the Imperial College London have shown the mechanism by which bacteriophages exploit other viruses to penetrate bacterial cells and replicate—a method akin to microbial piracy—which could eventually be applied for medical uses.
The study appears in the journal Cell, highlighting a key pathway through which bacteria gain new genetic information, including characteristics that can improve their virulence or antibiotic resistance. The researchers of the study indicate that this insight might also open doors to novel strategies to combat antimicrobial resistance (AMR) and develop speedier diagnostic methods.
Bacteriophages, or phages, are described as viruses that infect and destroy bacteria. Among the most numerous entities on the planet, phages are generally highly specialized, with each type typically focusing on a single bacterial species. The researchers pointed out that their structure is similar to a small syringe, with a DNA-packed “head” and a tail tipped with spiky fibers that link with the bacteria and inject their genetic material.
A vital factor is that, phages are susceptible to parasites as well. They can be hijacked by small genetic elements referred to as phage satellites, which make use the phage’s own genetic machinery to replicate and spread.
In a recent study, researchers at Imperial explored a potent group of phage satellites known as capsid-forming phage-inducible chromosomal islands (cf-PICIs). These genetic elements have the ability to transfer genes linked to antibiotic resistance and virulence and are present in more than 200 bacterial species. This mechanism is still unknown.
Originally identified by the team in 2023, cf-PICIs can assemble their own capsids—the “heads” of viruses—but lack tails. This means that, on their own, they generate non-infectious particles and cannot independently infect phages. In their latest research at Imperial’s Centre for Bacterial Resistance Biology, scientists uncovered the missing link: cf-PICIs hijack tails from unrelated phages, forming hybrid “chimeric” viruses. These chimeras carry cf-PICI DNA inside their capsids but have tails derived from other phages.
A vital factor is that some cf-PICIs can appropriate tails from completely different phage species, significantly making the range of bacteria they can infect more. Taking into account the fact that the tail is responsible for which bacteria a virus can target, this form of microbial piracy makes it possible for cf-PICIs to invade new bacterial species, shedding light on why they are so widespread in nature.
The researchers of the study point out that these findings have an exciting scientific potential. By understanding and potentially harnessing this molecular hijacking, it may be possible to engineer satellites to combat antibiotic-resistant bacteria, penetrate stubborn bacterial defenses such as biofilms, and even create advanced diagnostic tools.
“These pirate satellites don’t just teach us how bacteria share dangerous traits,” said Dr Tiago Dias da Costa, from Imperial’s Department of Life Sciences. “They could inspire next-generation therapies and tests to outmanoeuvre some of the most difficult infections we face.”
The Imperial research team has secured patents to advance this discovery and is preparing to test how the technology could be applied in practice.
Professor José Penadés, of Imperial’s Department of Infectious Disease, indicated that in their initial studies, they uncovered these unusual genetic elements, which behave like parasites of other parasites. He indicated that they now understand that these mobile genetic elements can build capsids and swap ‘tails’ from different phages to insert their own DNA into bacterial cells and it’s a clever twist of evolution, but it also reveals more about how antibiotic resistance genes spread through a mechanism known as transduction.
Dr. Dias da Costa stated that their experiments provide deeper insight into a vital pathway of gene exchange in bacteria. By harnessing and redesigning cf-PICIs, we may gain a powerful new approach in tackling antimicrobial resistance.
