Rapamycin Modulates Influenza Infection

Six-week-old C57BL/6 mice (Jackson Laboratories) were treated intraperitoneally (i.p.) daily (d) for the duration of the experiment with 500 μL of phosphate-buffered saline (PBS) containing 12 μg (high dose) or 1.5 μg (low dose) rapamycin (Rapamune oral solution, 1 mg/mL sirolimus; Pfizer) as described previously (1 (link),11 (link),17 (link)). Three days after treatment was initiated, mice were inoculated intranasally (i.n.) with 1.5 LD₅₀ of A/Puerto Rico/8/1934 (A/PR8) (H1N1) under avertin anesthesia (Supplementary Fig. S1A; Supplementary Data are available online at www.liebertpub.com/vim). Mice were monitored daily postinoculation for morbidity (weight loss) and mortality. All mice that lost 25% or greater body weight as determined by preinfection weight were humanely euthanized as per CDC-IACUC guidelines. Lungs were collected 6, 9, and 12 days and sera were collected 2 and 5 weeks postinoculation. Five to six weeks later, mice were challenged with a heterosubtypic virus, A/Hong Kong/1/68 (A/HK68) (H3N2), at 5 LD₅₀. All animal research conducted in this study was approved by the CDC-IACUC and was conducted in an AAALAC-accredited facility.