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A type of virus thought to be a "mere curiosity" is plentiful in one common bacteria, and possibly others, a Monash University-led research team has found.

The discovery improves understanding of how viruses work and could mean this particular virus is also common in other types of bacteria.

in Science Advances, the study looked at bacteriophages (phages), which are viruses that infect bacteria and come in many forms.

In particular, researchers investigated telomere phages, a type of phage that until now was considered a curiosity. Only their unique DNA replication mechanism had been studied.

Senior author and Monash Biomedicine Discovery Institute Bacterial Cell Biology Lab head Professor Trevor Lithgow said nothing had been known about whether telomere phages were a benefit or burden to their host cells.

He said the study, which sequenced a Klebsiella bacteria strain associated with pneumonia, found that telomere phages were prolific.

"This is astounding," Professor Lithgow said of the finding. "For more than 20 years of intensive bacterial genomics, telomere phages had remained hidden in plain sight. We have missed an entire aspect of biology.

"Serendipitously, when we sequenced a clinical Klebsiella strain and identified a fourth telomere phage, our sequence analysis led to the realization that telomere phages are not rare curiosities but highly prevalent throughout the thousands of lineages of Klebsiella, including strains collected from waterway environments.

"Our discovery of toxins that we call 'telocins' (for telomere-phage toxins) has a potential translation as a bacterial management strategy: 'good' bacteria carrying telomere phages will kill neighboring 'bad' Klebsiella. An example of 'bad' bacteria would be antibiotic-resistant Klebsiella."

First author Sally Byers, from the Lithgow Laboratory, noted that the work was significant due to the knowledge that would come from understanding a previously unknown element of bacterial biology.

"Our finding that telomere phages are so prevalent means that they are a selective force, one that we know little about," she said. "We now want to understand how the host secretes the toxin and also understand how the toxin wheedles its way into the unsuspecting bacterial neighbors.

"While all of our work has been done in Klebsiella, we predict that yet-to-be-discovered telomere phages may be common in other species of bacteria too."