Bacteriophages-symbionts
Scientists have discovered the first "useful" viruses
The work of Barr et al. Bacteriophage adhering to mucus provide a non-host-derived immunity is published in the journal Proceedings of the National Academy of Sciences, and its summary is given by ScienceNOW (Friendly Viruses Protect Us Against Bacteria).
The reason for the study was the discovery of an unusual ratio of the concentration of bacteriophages inside and outside the mucous membrane. It turned out that, for example, the concentration of bacteriophages in saliva is significantly less than in the oral mucosa itself.
In the course of further research, the scientists found that bacteriophages are not just present in the mucosa, they attach to the sugar residues of mucopolysaccharides with the help of special proteins that resemble antibodies in structure. By regulating the composition of these substances, the host organism is able to regulate the ratio of certain phages in the mucous membranes and manage their community.
The scientists established the protective nature of the detected phages by conducting an experiment in which a solution of bacteria with bacteriophages was added to the cell culture. It turned out that bacteriophages protect the cells of the body only if the latter is able to produce mucosal polysaccharides (in control cells, this ability was turned off due to mutation).
"Phage immunity," as the authors of the study called it, is an extremely rare case of commensalism between animals and viruses. Another example of such mutually beneficial cooperation (mediated, however, by bacteria) may be the protection of aphids from riders with the help of a toxin that produces the APSE virus.
Portal "Eternal youth" http://vechnayamolodost.ru22.05.2013