Researchers from the College of Natural and Mathematical Sciences of the University of Maryland, in Baltimore County, USA, were the first to see how two bacteriophage viruses interact and probably co-evolve.
The discovery was made using a microscope that directs electron beams at the object, writes Live Science.
“No one has ever seen a bacteriophage (or any other virus) attach to another virus“, – says Taghid de Carvalho, the lead author of the study and deputy director of the College of Natural and Mathematical Sciences of the University of Maryland.
The two viruses shown are bacteriophages or simply phages – viruses that attack bacteria. The smaller one (purple) is a satellite virus that is unable to infect and reproduce in host cells without the help of a helper virus (blue).
|INthe satellite virus (purple) is attached to the “neck” of the helper virus (blue). Photo: Tagide deCarvalho/UMBC|
“Satellite viruses rely on helper viruses to replicate their DNA after entering a cell. To coordinate their actions, the companion and helper must simultaneously infect the same the cell. For this you need to be close to them. But this image is the first time scientists have seen a companion joining a helper. It attaches to the “neck” of the virus – the place where the helper’s outer shell connects to its tail.”says the article published in the Journal of the International Society of Microbial Ecology.
The researchers made this discovery by accident while studying samples that contained companion bacteriophages that infect Streptomyces bacteria. At first, they thought the samples were contaminated because they contained large DNA sequences (expected bacteriophages) and smaller, unrecognizable sequences that didn’t match anything already known.
After further examination under a microscope, the authors discovered that the samples contained companion and helper bacteriophages. At the same time, satellites were attached to the necks of 80% of assistants. In some of the remaining helpers, the authors noticed something similar to “bite marks” – these were the consequences of their interaction, which left behind the remnants of antennae from the satellite.
“But why would a satellite grab the neck of its helper? It turns out that some satellites lack the gene necessary to integrate into the genome of bacterial host cells after entering them. Most satellite viruses can hide in the host’s DNA: and only when the right helper appears , they can reproduce”the researchers report.
To ensure that the companion-helper pair enters the host cell together, the companion attaches to the helper with a unique adaptation to its tail, the researchers found.
The researchers say the discovery could lead to new research, including the evolution of bacteriophages and how satellites attach to their helpers and how often this happens.
Iryna Batiuk, “UP. Life”
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