Parasites of viruses drive superbug evolution

A biological process by which bacteria share their genetic material through viruses has been discovered by scientists.

The newly discovered process is found to be more versatile and complex than previously known, similar mechanisms.

This ability to share genetic material is the major driver of microbial evolution because it can transform a benign bacterium to become harmful.

The insights could aid understanding of how bacteria rapidly adapt and evolve, to become more virulent and resistant to antibiotics.

Bacteria study

A team led by the National University of Singapore (NUS) and Imperial College London, in collaboration with the Roslin Institute, discovered the new process, termed lateral cotransduction, in Staphylococcus aureus bacteria.

It is driven by DNA elements, known as S. aureus pathogenicity islands (SaPIs), which exploit and parasitise phages – viruses that attack bacteria.

Phages can act as conduits that allow genes to transfer between bacteria.

Unlike phages that sacrifice their genes to transmit bacterial DNA, SaPIs can transfer themselves intact with bacterial DNA.

This remarkable capability enables them to perpetually repeat the process, making them potent, efficient transmitters of bacterial genes.

The study demonstrates that bacteria can evolve much faster than previously understood.

The rise of superbugs has called for new ways to treat antibiotic-resistant strains, such as phage therapy, using phages to eliminate harmful bacteria. However, this finding suggests that some therapeutic phages could instead enable bacteria to evolve.

Scientists at the Roslin Institute carried out population genomic analysis of S aureus, to demonstrate the impact of lateral transduction on bacterial evolution and genome structure for the study, published in Cell.

This new insight opens up avenues of research to better understand how bacteria evolve by acquiring genes, promoting their ability to survive in different niches.

Professor Ross Fitzgerald

They (phages) could be used to destroy bacteria in the short term but end up spreading harmful genes to other cells in the long term … with this new way of understanding the evolutionary mechanisms of disease-causing organisms, it is important for therapeutic phages to be carefully vetted before they are used for therapy.

Assistant Professor John Chen

** The Roslin Institute receives strategic investment funding from the Biotechnology and Biological Sciences Research Council and it is part of the University of Edinburgh’s Royal (Dick) School of Veterinary Studies. **

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