design: Female C57BL/6 mice (68 weeks) were housed under SPF conditions and randomly assigned to treatment groups under IACUC-approved protocols. For this group, animals received vehicle (PBS, intraperitoneal; 500 L) on day 1, day 0, and days +1 and +3 relative to infection. Mice were challenged intranasally (50 L) with a sublethal dose (0.5 LD50) of Influenza A virus H1N1 IVR-180 prepared on embryonated eggs and titrated on MDCK cells. Animals were monitored for 5 days post-infection. On day 5 post-infection, whole blood was collected by cardiac puncture into EDTA tubes for RNA extraction. rRNA/globin-depleted RNA-seq libraries were prepared (NEBNext Ultra II; QIAGEN FastSelect HMR+Globin) and sequenced on an Illumina NovaSeq (2150 bp, paired-end).