FUT4 and HIV infectious disease: Since neutrophil population plays a protective role during HIV infection (22), we also evaluated the differentiation of neutrophils in these humanized mice by staining typical neutrophil markers CD15 and CD66b within the CD14 negative population, and we found ~4% CD14-CD15+ cells and ~3% CD14-CD66b+ cells, demonstrating the differentiation of neutrophils in the humanized mice (Supplementary Figure 2).