design: Female C57BL/6 mice (68 weeks) were housed under SPF conditions and randomized (IACUC-approved). For this group, animals received Triacsin C (0.05 mg in PBS, intraperitoneal; 500 L) on one day before mock infection, and were mock-infected intranasally with sterile PBS (50 L). Animals were observed for 5 days post-procedure. On day 5, whole blood was collected by cardiac puncture into EDTA tubes for RNA extraction, providing a drug-only control without viral challenge. rRNA/globin-depleted RNA-seq libraries (NEBNext Ultra II; QIAGEN FastSelect HMR+Globin) were sequenced on an Illumina NovaSeq (2150 bp, paired-end)