Viruses can ‘decide’ when to kill host cells

(ORDO NEWS) — Scientists have found that bacteriophages viruses of bacteria have a common ability to track changes that occur inside their host cell and choose when to leave it.

The results of the study may have implications for the development of new antiviral drugs.

Scientists from the University of Maryland in Baltimore (USA) have shown that viruses use information about the environment to decide when to stay inside the host cell and when to multiply and go outside, killing it.

The ability of the virus to sense its surroundings adds “another layer of complexity” to interactions with the host, the researchers said. However, it is likely that this mechanism can also be used to create antiviral drugs.

The authors of the work studied bacteriophages – viruses that infect bacteria. Many of them infect only those bacteria that have villi (drank) or flagella. Viruses enter the host cell through them.

The synthesis of these processes is accompanied by the production of the CtrA protein, and scientists have found that many bacteriophages have special patterns in their DNA – binding sites to which CtrA can attach.

These sites were not unique to one particular bacteriophage or group. It turned out that they are inherent in a huge variety of viruses that infect bacteria with flagella and / or villi.

According to the authors, this ability to track CtrA levels inside the cell appeared several times in the evolution of viruses.

The first bacteriophage in which the research team found CtrA binding sites infects the bacteria Caulobacterales . They can exist in two forms – “free-floating” and “stalked”, attached to the surface.

The first has villi, the second does not. In Caulobacterales, the CtrA protein also regulates the cell cycle, and its level indicates whether a cell will divide into two cells of the same type or two cells of different shapes.

Phages can only infect free-floating cells, and they need to leave the host cell at a time when there are many cells around to infect.

As a rule, Caulobacterales exist as single cells in a nutrient-poor medium , and when they find a place, they turn into a colony of stalked cells with a nutrient medium.

Bacteriophages monitor CtrA levels as they change throughout the life cycle of cells to find out when a free-swimming cell becomes stalked and starts producing new free-swimming cells that the virus can infect.

Scientists believe that a similar mechanism may exist in viruses that infect humans and animals. For example, to optimize its survival strategy, a virus is able to learn what tissue it is in or how strong the host’s immune response is to its presence.

The discovery also provides opportunities to create new treatments for infectious diseases.


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