Gut Microbiota May Influence the Severity of COVID-19, RSV, and Flu

A new mouse study shows certain gut bacteria may help protect against respiratory viral infections.

A new mouse study has found that certain segmented filamentous bacteria (SFB), when naturally present or introduced into the intestinal microbiome, cause the lungs’ alveolar macrophages to disable viral infections and protect against illness.

The results show that mice were more capable of resisting serious respiratory illnesses like respiratory syncytial virus (RSV) and SARS-CoV-2, the virus that causes COVID-19, as well as influenza viruses.

Alveoli are tiny air sacs in your lungs — an estimated 480 millionTrusted Source of them — that take in oxygen and convert it to carbon dioxide.

In the presence of the segmented filamentous bacteria, macrophages resident in the alveoli somehow destroyed the pathogens directly without triggering the immune system’s larger inflammatory response.

During the study, mice were exposed both to RSV and SARS-CoV-2. In mice without segmented filamentous bacteria, alveolar macrophages became quickly depleted in the presence of the pathogens.

However, in mice with segmented filamentous bacteria, alveolar macrophages changed in two ways. First, they became resistant to the pathogens. Second, they became pathogen-neutralizers, disabling them.