English: Eight-week-old mice were intranasally inoculated with 7,000 PFU of rSeV-luc(P-M), rSeV-luc(F-HN), or rSeV-luc(M-F*). Every 24 hours the mice were intraperitoneally injected with luciferin substrate, anesthetized with isoflurane, imaged with a Xenogen IVIS device, and then allowed to recover. Bioluminescence in one experiment is shown on day 2 (A) and day 7 (B) post-infection (p.i.) in 129/SvJ mice infected with rSeV-luc(P-M), rSeV-luc(F-HN), or rSeV-luc(M-F*). Bioluminescence in a second experiment is shown on day 2 (C) or day 7 (D) for 129/SvJ, DBA/2, BALB/c, or C57BL/6 mice infected with rSeV-luc(M-F*). The data are displayed as radiance (bioluminescence intensity) on a rainbow log scale with a range of 1×106 (blue) to 1×109 (red) photons/s/cm2/steradian. Red circles indicate regions of interest (ROI) used to calculate the total flux (photons/s) in the nasopharynx, and red rectangles indicate the ROI areas for the trachea and lungs.