FIG. 1.

MNV-1 causes dose-dependent mild diarrhea in wild-type mice. (A) 129SvEv or C57BL/6 mice were inoculated perorally with the indicated doses of MNV-1 at 5 to 6 weeks of age. All mice were fasted for 18 to 20 h prior to sample collection. At 72 hpi, mice were sacrificed and all feces below the cecum was collected and scored (0, normal feces; 1, mixed stool samples containing both solid and pasty feces; 2, pasty feces; 3, semiliquid feces; 4, liquid feces) independently by two investigators. At least one investigator scored the samples blindly. The data are presented as the frequency of mice receiving a score of 1 or greater from both investigators. Raw diarrheal scores are presented in Table 1. (B and C) Groups of 129SvEv mice (10 to 40 mice per group) were inoculated perorally with the indicated doses of MNV-1 at 5 to 6 weeks of age and fasted for 18 to 20 h prior to sample collection. At 24 hpi, mice were sacrificed and all feces below the cecum was collected, scored as described above, and immediately weighed. The feces was then dried at 70°C overnight and reweighed. Wet/dry ratios were determined by dividing the initial weight by the dried weight. The P values comparing MNV-1-infected mice to mock-infected mice are 0.0091 for 10⁴-PFU infections and ≤0.0001 for 10⁷-PFU infections (B). In panel C, wet/dry ratios are separated based on their score by visual assessment of fecal consistency.