A bidirectional brain-fat body axis for pathogen avoidance.

A bidirectional fat body-brain pathway in Drosophila melanogaster mediates pathogen avoidance through immune detection and neural signaling.

• Why it matters: Understanding how immune responses influence behavior is crucial for revealing survival strategies against pathogens, yet the mechanisms linking immune detection to behavioral changes are largely unknown.
• What they did: The study identified immune receptors and antimicrobial peptides in both fat body and neurons, showing that pathogen sensing activates octopaminergic neurons, which trigger dopamine release in the fat body, ultimately driving avoidance behavior via mushroom body neurons.
• The result: This work uncovers a novel immune-to-brain communication loop that links immune activation to behavioral adaptation, providing insights into how innate immune responses can modulate behavior to improve survival during infection.