Cell-specific responses of Anopheles gambiae fat body to blood feeding and infection at single-nuclei resolution

The mosquito fat body plays key roles in metabolism and immunity, yet its cellular diversity and specialization remain poorly understood. This study analyzed 97,650 nuclei from the female Anopheles gambiae abdominal body wall at single-nucleus resolution, identifying seven major cell types. Fat body trophocytes are most abundant ( ~ 85%), with five subpopulations: basal (T1, T2), metabolically enriched (T3), immune-responsive (T4), and a vitellogenic group (T5) found only in blood-fed females. Sessile hemocytes comprise 7.4% of cells and expression of lipid biosynthesis enzymes increase in oenocytes (1.1%) after immune priming. T4 trophocytes consistently express immune genes, while various cell types respond to bacterial infection. Blood feeding induces extensive transcriptomic changes, notably upregulating vitellogenin and DNA replication genes, indicating trophocyte endoreplication and metabolic shifts. Vitellogenin mRNA was expressed in the first layer of trophocytes facing the hemolymph with apical subcellular localization. This high-resolution atlas reveals specialized trophocyte roles in mosquito immunity and reproduction.