New IgY Antibody Detects Drosophila Insulin-Like Peptide 2 in Fly Brains

Researchers have generated and validated a polyclonal IgY antibody capable of detecting endogenous Drosophila melanogaster insulin-like peptide 2 (DILP2) in fly tissues, addressing a long-standing bottleneck in the study of insulin signaling in one of biology’s most important model organisms. The work, published as an open access article in BMC Molecular and Cell Biology, describes the cloning, bacterial expression, and immunological evaluation of recombinant DILP2, culminating in an antibody that specifically labels the insulin-producing cells of the adult fly brain.

Insulin signaling sits at the heart of metabolism across the animal kingdom, and disruptions to its pathways are implicated in metabolic, cardiovascular, neurodegenerative, and reproductive pathologies. Because the insulin pathway is evolutionarily conserved, Drosophila melanogaster serves as a powerful model for studying insulin-dependent glucose regulation. Among the fly’s insulin-like peptides, DILP2 is highly similar to human insulin in conserved sequence and structure; human insulin is a key regulator of carbohydrate storage and glucose homeostasis, which makes DILP2 a central focus of functional studies. Yet despite the use of anti-DILP2 antibodies in various studies, the limited availability of specific antibodies has constrained detailed functional and histological work on this peptide.

To build a new reagent, the team cloned the dilp2 gene into the pET-21a vector and expressed the recombinant protein in Escherichia coli. In this bacterial expression system, the recombinant DILP2 accumulated predominantly as inclusion bodies. This technical detail turned out to matter more than a routine expression note might suggest, because the physical state of the antigen shaped the immune response that followed.

The researchers immunized hens under two conditions: one with inclusion body-derived DILP2 and one with refolded DILP2. The two preparations produced markedly different antibody responses. Although the single hen immunized with inclusion body-derived DILP2 showed a higher total IgY level, detectable antigen-specific antibodies were obtained only following immunization with the refolded protein. In other words, a higher total IgY level did not translate into a detectable, target-specific reagent; the findings suggest that the structural state of recombinant antigens may influence the generation of antibodies capable of recognizing endogenous targets.

The resulting IgY-DILP2 antibody from this study specifically labeled the insulin-producing cells, or IPCs, in the adult fly brain, the neuroendocrine cells where DILP2 is naturally produced.

Validation went further using a previously characterized dUCH-knockdown model, a genetic system in which changes in endogenous DILP2 immunoreactivity had already been reported. The new antibody reproduced those previously reported changes: a significant reduction in the number of DILP2-positive IPCs accompanied by increased DILP2 fluorescence intensity in the axonal bundles.

Specificity testing also extended to potential cross-reactivity with the fly’s other insulin-like peptides. No detectable IgY-DILP2 immunoreactivity was observed in the midgut, a tissue where other DILPs are expressed, providing further evidence against detectable cross-reactivity with endogenous DILP3 and DILP5 under the experimental conditions used.

The antibody was not without limits. It effectively detected endogenous DILP2 by immunofluorescence but failed to detect it by Western blot analysis of fly brain extracts. The authors suggest this may reflect differences in antigen conformation between the two assay formats and/or the low abundance of endogenous DILP2 in whole-brain samples.

The authors conclude that the study describes the generation of a polyclonal IgY antibody capable of detecting endogenous DILP2 in Drosophila tissues, and that the findings suggest the structural state of recombinant antigens may influence the generation of antibodies capable of recognizing endogenous targets. They also acknowledge a notable limitation: the immunization comparison relied on a single hen per condition, which limits how much can be generalized about the differences between inclusion body-derived and refolded antigen preparations.

Subject of Research: Generation and validation of a polyclonal IgY antibody for detecting endogenous Drosophila insulin-like peptide 2

Article Title: Generation and validation of polyclonal IgY antibodies for detection of endogenous Drosophila melanogaster insulin-like peptide 2

Article References: Le, H. K., Nguyen, H. T.-K., Dao, L. M., Mai, T. T.-T., Nguyen, V. Q., Hoang, T. T., & Dang, T. T.-P. (2026). Generation and validation of polyclonal IgY antibodies for detection of endogenous Drosophila melanogaster insulin-like peptide 2. BMC Molecular and Cell Biology. https://doi.org/10.1186/s12860-026-00601-y

Image Credits: AI Generated

DOI: 10.1186/s12860-026-00601-y

Keywords: Drosophila melanogaster, DILP2, IgY antibodies, insulin signaling, inclusion bodies, protein refolding, immunofluorescence, antibody validation, insulin-producing cells, cross-reactivity, Western blot, BMC Molecular and Cell Biology