STAT1 and Increased total leukocyte count: Given that we observe high expression of IRG genes during HSPC expansion and robust enrichment of IFN- and STAT1-related genes in HSPCs of both naïve infection and WCV immunization, it can be argued that IFN influence on primitive hematopoietic cells is important in expanding bone marrow HSPCs for the promotion of leukocytosis.