Discovery of a fight between two viruses within the bacterium Acinetobacter baumannii with potential therapeutic application
published on 16/01/2025
Research team led by Antonio Pérez Pulido analyze how bacteriophages compete and contribute to the understanding of the biology of antibiotic resistant bacteria.
The bioinformatics and computational biology research group of the Universidad Pablo de Olavide UPOBioinfo, which carries out its research at the Andalusian Center for Developmental Biology (CABD), has unveiled a fascinating conflict between bacterial viruses, known as bacteriophages or phages. This discovery, recently published in the journal Cell Reports, could shed light on new strategies to combat infections caused by antibiotic-resistant bacteria.
The research, focused on the bacterium Acinetobacter baumannii, has revealed how two competing viruses, which they have named PPTOP (nicknamed 'Terminator') and DgiS1, wage a battle using this bacterium as a stage. Both viruses have developed sophisticated attack and defense systems that not only allow them to fight each other, but also appear to indirectly benefit the bacterium by providing it with tools to defend itself against other viruses.
Using bioinformatics tools and employing the C3UPO supercomputer of the Pablo de Olavide University, we consulted a public database where 9000 bacterial genomes are available. By analyzing which viruses were integrated into the genome of the bacterium Acinetobacter baumannii, we discovered the battle between these two viruses,” explains UPO professor Antonio J. Pérez Pulido, principal investigator of the study.
A relevant finding in the fight against superbugs
Acinetobacter baumannii is considered a priority threat by the World Health Organization due to its resistance to all antibiotics available on the market and its role in serious hospital infections. In this context, phage therapy, a strategy that uses viruses to fight bacteria, is gaining interest. Thus, this study provides new insight into how bacteriophages interact with each other and with their host.
The 'Terminator' virus employs a CRISPR-Cas system, a highly efficient antiviral mechanism, to block infections by the DgiS1 virus. On the other hand, DgiS1 responds with mutations in its genome that make it resistant to the Terminator attack. These clashes take place in a specific region of the bacterial genome known as the “defense archipelago”, an arsenal of antiviral genes apparently mobilized by the viruses themselves.
Fight between the phages PPTOP and DgiS1 for integration into the genome of the bacterium Acinetobacter baumannii. Watercolor by Silvia Cano Martos.
Evolutionary success and clinical relevance
The UPOBioinfo team has found that the DgiS1 virus is prevalent in more than half of the analyzed genomes of A. baumannii. Interestingly, strains carrying this virus are the most frequently isolated in hospital-acquired infections, suggesting its success in this setting.
“This finding not only gives us a more detailed view of how viruses and bacteria interact in nature, but may also be key to developing new strategies against antibiotic-resistant bacteria,” says Antonio J. Pérez Pulido.
The discovery, in addition to contributing to the fundamental understanding of bacteria-virus dynamics, could pave the way towards more effective treatments against pathogenic bacteria, a critical challenge in modern medicine.
Alejandro Rubio, Andrés Garzón, Antonio Moreno-Rodríguez, Antonio J. Pérez-Pulido. Biological warfare between two bacterial viruses in a defense archipelago sheds light on the spread of CRISPR-Cas systems. Cell Reports. 2024 Dec. DOI: 10.1016/j.celrep.2024.115085
Thus press release was wiritten in collaboration with the Communication Unit at UPO.