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Updated: Jun 17, 2026
Systemic Bacterial Infection and Immune Defense Phenotypes in Drosophila Melanogaster
Published on: May 13, 2015
The Drosophila Baramicin polypeptide gene protects against fungal infection
Mark Austin Hanson1, Lianne B Cohen2, Alice Marra1
1Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
Abstract:
The fruit fly Drosophila melanogaster combats microbial infection by producing a battery of effector peptides that are secreted into the haemolymph. Technical difficulties prevented the investigation of these short effector genes until the recent advent of the CRISPR/CAS era. As a consequence, many putative immune effectors remain to be formally described, and exactly how each of these effectors contribute to survival is not well characterized. Here we describe a novel Drosophila antifungal peptide gene that we name Baramicin A. We show that BaraA encodes a precursor protein cleaved into multiple peptides via furin cleavage sites. BaraA is strongly immune-induced in the fat body downstream of the Toll pathway, but also exhibits expression in other tissues. Importantly, we show that flies lacking BaraA are viable but susceptible to the entomopathogenic fungus Beauveria bassiana. Consistent with BaraA being directly antimicrobial, overexpression of BaraA promotes resistance to fungi and the IM10-like peptides produced by BaraA synergistically inhibit growth of fungi in vitro when combined with a membrane-disrupting antifungal. Surprisingly, BaraA mutant males but not females display an erect wing phenotype upon infection. Here, we characterize a new antifungal immune effector downstream of Toll signalling, and show it is a key contributor to the Drosophila antimicrobial response.
Insights
Fruit flies produce immune peptides to fight microbes. Researchers identified a new antifungal peptide gene, Baramicin A (BaraA), crucial for combating fungal infections and enhancing survival.
Area of Science:
- Immunology
- Genetics
- Entomology
Background:
- Fruit flies (Drosophila melanogaster) combat microbial infections using secreted effector peptides.
- Investigating short immune effector genes was challenging until the CRISPR/Cas era.
- Many putative immune effectors are uncharacterized, limiting understanding of their role in survival.
Purpose of the Study:
- To describe a novel Drosophila antifungal peptide gene, Baramicin A (BaraA).
- To characterize the function and immune role of BaraA.
- To investigate the contribution of BaraA to survival against fungal pathogens.
Main Methods:
- Gene identification and characterization of Baramicin A (BaraA).
- Analysis of BaraA expression patterns in different tissues.
- Functional assays using BaraA knockout and overexpression fly models.
- In vitro synergistic antifungal activity assays.
Main Results:
- A novel antifungal peptide gene, Baramicin A (BaraA), was identified in Drosophila.
- BaraA is immune-induced downstream of the Toll pathway, primarily in the fat body.
- Flies lacking BaraA exhibit susceptibility to Beauveria bassiana, while overexpression confers resistance.
- BaraA-derived peptides show synergistic antifungal activity with membrane-disrupting agents.
- BaraA mutant males display an erect wing phenotype upon infection.
Conclusions:
- Baramicin A is a novel antifungal immune effector in Drosophila.
- BaraA plays a significant role in the fruit fly's antimicrobial defense against fungi.
- BaraA functions downstream of Toll signaling and contributes to host survival.
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