FIG. 2.

MNV-1 is infectious at low doses. (A) 129SvEv mice were inoculated perorally with the indicated doses of MNV-1 at 5 to 6 weeks of age. At the postinfection times indicated, animals were perfused, organs were harvested, and viral burdens were determined by plaque assay. A minimum of three mice were analyzed for each dose and each time point. For clarity, high-dose (10³ to 10⁷ PFU) and low-dose (10 and 100 PFU) groups are shown in separate graphs. (B) 129SvEv mice were infected with the indicated doses of MNV-1 or mock infected at 5 to 6 weeks of age. At 6 weeks postinfection, serum was collected and analyzed for virus-specific IgG or IgA by enzyme-linked immunosorbent assay.