IL1B and Zika virus infectious disease: Notably, when we measured IL-1β+ populations of ZIKV+ versus ZIKV– for both microglia and macrophages, IL-1β + population of ZIKV+ macrophages but not ZIKV+ microglia, was significantly increased by ZIKV infection, indicating that ZIKV-infected macrophages are the source of IL-1β in the brain (Fig. 5F and G).