Virus titers in the nasal mucosa, lungs, submandibular glands, saliva, plasma, spleen, liver and kidneys. These tissues were collected from mice upon oronasal inoculation with either a low (104TCID50/mouse, left column) or a high (106TCID50/mouse, right column) inoculation dose. Virus titers (log10 TCID50/g or log10 TCID50/mL) were measured by titration. Open circles represent HaNa1-infected mice and closed circles represent Smith-infected mice. The detection limit for the titration (102.1 TCID50/g) is shown by the horizontal dotted line.