Imaging was performed on 0, 1, 2, 3, and 6 days post-infection (DPI). Each day, four ferrets were imaged with CT and PET on hardware designed for preclinical animal studies, including microCT and microPET, respectively. Two ferrets were euthanized the each day and necropsied to obtain tissue samples for virologic and histopathologic analyses (please see study design Table 1 ). Image acquisition was conducted with a Siemens Inveon Trimodal Scanner (Siemens Preclinical, Knoxville, TN), which is a small animal imaging platform that combines microPET, microCT, and microSPECT modalities within one unit. This combination facilitated co-registration of PET and CT images as the study subject was kept in a uniform position on the scanner bed, minimizing potentially large motion artifacts as a result of repositioning the animal between each scan. The Inveon microCT scanner features a variable-focus tungsten X-ray source with an achievable resolution of 20 mm and a detector with a maximum field of view (FOV) of 8.4 cm65.5 cm. The source-to-object distance was 263.24 mm and the source-to-detector distance was 335.67 mm. The Inveon PET detector provided an axial field of view (FOV) of 12.7 cm with a spatial resolution of 1.44 mm. PET images were reconstructed using a 2D-filtered backprojection algorithm with attenuation correction provided by microCT imaging. For the microCT scan, the following imaging settings were used: two bed positions, 80 kVp, 500 mA, 500 ms exposure time, and 464 binning. After each ferret underwent microCT imaging, the bed position was reset and microPET imaging with 18F-FDG (PETNET, Louisville, KY) began immediately. For each ferret, 2 mCi of 18F-FDG was administered (i.p.) with a 60-90 min uptake period. Radioactive dose was confirmed with an Atomlab 500 Dose Calibrator (Biodex Medical Systems Inc., NY).