A study at the Weizmann Institute of Science has revealed that viruses communicate with one another to proceed with the process of infection. Reporting in the journal Nature, Prof. Rotem Sorek and his group in the Weizmann Institute’s Molecular Genetics Department say that during an infection, viruses leave messages (by secreting small molecules) which other viruses can pick up and read, and this way, they coordinate their attack, “turning simple messages into a fairly sophisticated strategy.”
In the study, the team grew bacteria in culture and infected them with phages. They then filtered the bacteria and phages out of the culture, leaving only the smallest molecules that had been released to the medium. Later, when they grew more bacteria on the filtered medium infecting them with the same phages, they found that the new phages became dormant rather than killing the bacteria. The team also worked on to isolate the communication molecule, but it eventually led to the discovery that it was a small piece of protein called a peptide which viruses use as a medium of communication. They also found that in the presence of high concentrations of this peptide, phages chose the dormancy strategy, so they named it arbitrium, the Latin word for decision. These peptide molecules enabled each generation of viruses to communicate with successive generations by adding to concentrations of the arbitrium molecule, which helped the later viruses to count how many previous viruses have succeeded in infecting host cells, and thus decide which strategy is most preferable, that is to attack their host or to lie dormant – at any point in time.
The team also noted that the communications between phages was discovered almost by accident. “We were looking for communication between bacteria infected by phages, but we realized that the small molecules we were finding had been sent by the phages themselves,” said Sorek in a news release. “We don’t really know how viruses that infect the human body decide to go dormant. It is possible that a similar strategy to that of the phages could be used by viruses that infect us.” HIV, herpes and the number of other human viruses, face similar decisions when invading a cell.
Reference: Communication between viruses guides lysis–lysogeny decisions – Nature