Viruses Supercharge Superbug Evolution

Viruses can transfer large chunks of bacterial genomes—including antibiotic resistance genes—among bacteria species.

AsianScientist (Oct. 23, 2018) – Scientists in Singapore and the UK have identified a mechanism of bacterial evolution which is at least a thousand times more efficient than any currently known mechanism. The insights will help scientists better understand how dangerous bacteria can rapidly adapt and become increasingly harmful and antibiotic resistant. Their findings are published in Science.

The prolonged and widespread use of antibiotics has resulted in the development of bacteria strains that are not only resistant to commonly used antimicrobial drugs such as penicillin, but also resilient against antibiotics of last resort such as carbapenems.

From a genetics perspective, the rapid rise of antibiotic resistance can be attributed to the sharing of antibiotic resistance genes among bacteria species in a process known as genetic transduction. Bacteriophages—viruses that infect bacteria—have been implicated in facilitating the gene transduction process.

In the present study, research groups from the National University of Singapore (NUS) and the University of Glasgow, UK, have identified a significantly more efficient mechanism by which bacteriophages transfer antibiotic resistance genes among bacteria. They called the mechanism lateral transduction.

The scientists demonstrated that bacteriophages carry long stretches of the Staphylococcus aureus bacteria genome—including antibiotic resistance genes—during the DNA packaging phase of viral replication. This occurs at very high frequencies, which means that large amounts of genetic material are transferred at a high rate when these bacteriophages infect other bacteria strains. By driving rapid mutation and acquisition of new genes, the researchers believe lateral transduction is a major contributor to the development and spread of antibiotic resistance.

“Phages [viruses] are by far the most abundant biological entities on the planet, and the importance of genetic transduction as one of the principle drivers of microbial evolution has never been more apparent than with the discovery of lateral transduction,” said Assistant Professor John Chen from the Yong Loo Lin School of Medicine at NUS, who is the lead author of the study.

This research also challenges current scientific thinking, which assumes that only mobile genetic elements of viral origin, and not the bacterial chromosomes, can be transferred at high frequencies.

“Lateral transduction elevates the concept of mobile genetic elements well beyond that of defined DNA elements, by transforming sections of the genome into ‘hypermobile platforms’ that are capable of transferring any genetic element within their boundaries at incredibly high frequencies,” added Chen.

The article can be found at: Chen et al. (2018) Genome Hypermobility by Lateral Transduction.


Source: National University of Singapore.
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