Antiviral microflora
Intestinal microflora proved to be important for protection against influenza
Sergey Vasiliev, Naked Science
The bacterial population of the intestine plays a huge role in protecting the body from pathogens. And we are talking not only about infections affecting the gastrointestinal tract, but even about the flu, which attacks the respiratory tract. An international team of scientists demonstrated this in experiments with laboratory mice, which are described in an article published in the journal Cell Reports (Bradley et al., Microbiota-Driven Tonic Interferon Signals in Lung Stromal Cells Protect from Influenza Virus Infection).
Interferons play a key role in the antiviral defense of our body. Alpha- and beta-interferons (IFNa and β) of type I are embedded in many signaling pathways that are "tuned" extremely precisely in order to trigger protective mechanisms at the right moment, but not to turn them on unnecessarily, so as not to cause damage associated with chronic inflammation. At the same time, the mechanisms of triggering and action of IFNa/β remain poorly understood.
To investigate them, the scientists used GM mice with innate enhanced expression of the IFNAR1 receptor, which is affected by IFNa/β interferons. Such animals showed increased resistance to viral infections, and when they had the flu, they tolerated it more easily and recovered faster. Their survival rate was about 80 percent.
However, all these benefits disappeared as soon as the mice were treated with antibiotics. The changes in the intestinal microflora caused by this led to a decrease in the activity of interferons in the lining cells of the lungs, so that the mortality rate for influenza infection was about 2/3 of the animals.
At the same time, fecal transplantation with the restoration of healthy microflora restored their ability to resist the influenza virus.
"Inappropriate use of antibiotics leads not only to the appearance of bacteria resistant to them, to the death of intestinal commensal microbes that are useful and protect us, but also makes the body more susceptible to viral infection," the authors summarize. They add that this may also apply to farm animals, which often receive antibiotics as a "preventive measure" and in fact become only an easier target for viruses.
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