Viruses trick the immune system by using friendly bacteria as a disguise
Last reviewed: 20.11.2021
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Bacteria of the intestinal microflora maintain peaceful relations with our immunity. Some viruses have managed to turn this in their favor: they pass under the radar of immunity, literally riding the friendly bacteria and using them as a disguise.
It's no secret that without a bacterial microflora a person would not have lived a day. The majority of microorganisms that constantly "rent" living space in our body, pay not the first look with inconspicuous, but irreplaceable services. For example, the largest bacterial diaspora - gastrointestinal microflora - helps us digest food, supplies us with important nutritional components of our own production. In addition, the microflora helps to ward off attacks of pathogenic bacteria and helps to cleanse the body of harmful substances.
It is clear that friendly bacteria should be able to negotiate with the immune system so that it does not attack them. For thousands of years of cohabitation, our immunity has learned to distinguish bacterium-friends from bacteria-enemies. It turned out that some viruses decided to take advantage of this. In one of two articles published in the journal Science, it is said about the virus of poliomyelitis, which penetrates the body with the help of gastrointestinal bacteria; the second article "blames" in the same virus of breast cancer in mice (MMTV). In both cases, scientists eradicated bacterial microflora in mice with antibiotics, and then looked at how this affected the infectious properties of the viruses.
In the first case, poliovirus infected animals twice as badly as in the presence of bacteria. The same was shown for MMTV. Moreover, the researchers checked how the transmission of the breast cancer virus from mother to baby will occur. This virus is transmitted along with the mother's milk, but if the mother and the cub did not have any intestinal microflora, the cub showed resistance to the virus. However, it was only in the intestines of the cub that bacteria appeared, as the body was opened for the virus.
The cell wall of the bacterium is composed of lipopolysaccharide molecules, which in the case of friendly microorganisms serve as something like identity cards. The bacterium shows its "credentials" to immune cells, which triggers a chain of reactions leading to suppression of the immune response to the presence of these bacteria. So, according to the authors of the articles, the viruses literally sit on the bacteria: after covering themselves with bacterial lipopolysaccharide, they evade the immune attack.
Perhaps, similarly, the virus of poliomyelitis penetrates into the human body. True, it is unclear what to do with this: do not eradicate the preventive intestinal microflora so as not to get poliovirus!