Basal Expression of Interferon-Stimulated Genes Drives Population Differences in Monocyte Susceptibility to Influenza Infection

There is considerable inter-individual immunological and clinical variability upon influenza A virus (IAV) infection in humans; yet, the factors underlying such heterogeneity remain elusive. Here, using an ex vivo cellular model that captures natural human variation in the transcriptional responses of monocytes to IAV, we find significant differences in viral mRNA levels between individuals of African and European ancestry. Using single cell analyses, we show that the overall number of cells that will ultimately become infected, rather than the amount of viral transcript expression per cell, is the main driver of the higher IAV mRNA levels detected in European cells. Finally, we identify 135 genes, including the interferon-stimulated genes IFITM3, MX1, and OAS3, for which basal mRNA expression levels associate with IAV mRNA levels post infection. Our findings reveal that basal differences in activation of IRF/STAT-induced antiviral mechanisms may contribute to individual and population disparities in susceptibility to IAV infection.