Fruit flies develop specific defenses against common bacteria; may explain human susceptibility to infection


Representative photo: iStock.

Bacteria in their food and environment shape the immune system of fruit flies, the study notes

Representative photo: iStock.

The immune system of fruit flies develops certain genes that can fight common bacteria found in food, according to a new study.

Bacteria such as Acetobacteria found in fruit can harm flies once they leave the intestines and reach the bloodstream. However, several species of flies have evolved a specific peptide (strings of compounds that combine to form proteins) that can fight off acetobacter, notes the study published in the journal Science on July 21, 2023.

The findings are crucial as the evolutionary process of fruit flies could help explain human susceptibility to certain diseases, noted researchers from the Swiss Federal Institute of Technology and the University of Exeter.

How our bodies resist infection is complex. But this kind of research helps us see our immune systems in a new light, said Mark Hanson of the University of Exeter.

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“I hope it leads us to wonder why our immune systems are made the way they are. This can help us fight infections, including infections that are resistant to antibiotics,” she added.

The bacteria in their food and environment shape the immune system of fruit flies. These flies have evolved two peptides to defend a single bacterial species that affects them.

Some of these peptides are common in some species. Several species of flies have evolved a particular peptide (diptericin B) to control acetobacter, the study added.

“This peptide is the silver bullet that kills this specific bacterium. Without it, flies are extremely vulnerable because acetobacter is so common in rotten fruit.”

Food and the environment shape the animal “microbiome,” the group of microbes that live in an organism. “Our study shows how immune systems evolve in response to this, to control common bacteria that might otherwise cause harm,” Hanson said.

‘Studies like this yield fundamental observations about life, and these in turn may have crucial applications in the world around us,’ he added.

While this study states how fruit flies defend foodborne bacteria, a 2021 study explained how these flies respond to food poisoning. The study explains how olfactory responses keep them from consuming the food that caused a previous infection, in the same way that we keep ourselves from eating the food that caused food poisoning.

Glial cells and neurons in the fly’s brain communicate, dampening the sense of smell and protecting the animals from re-consuming the pathogen after an intestinal bacterial infection, notes the study published in the journal Nature.