Dense time-course gene expression profiling of the Drosophila melanogaster innate immune response

Abstract

Immune responses need to be initiated rapidly, and maintained as needed, to prevent establishment and growth of infections. Still, immune genes differ in both initiation kinetics and shutdown dynamics. Here, we performed an RNA-seq time course on D. melanogaster with 20 time points post-LPS injection. A combination of methods, including spline fitting, cluster analysis, and Granger Causality inference, allowed detailed dissection of expression profiles and functional annotation of genes through guilt-by-association. We identified antimicrobial peptides as immediate-early response genes with a sustained up-regulation up to five days after stimulation, and genes in the IM family as having early and transient responses. We further observed a strong trade-off with metabolic genes, which strikingly recovered to pre-infection levels before the immune response was fully resolved. This high-dimensional dataset enables the comprehensive study of immune response dynamics through the parallel application of multiple temporal data analysis methods.