FIG 5.

Virus attenuation in immunodeficient mice. (A and B) Groups of 6- to 7-week-old NOD-scid mice or 6- to 8-week-old IFNAR^−/− mice were infected with 10³ to 10⁵ PFU i.v. (scid mice) or 10² to 10⁵ PFU i.p. (IFNAR^−/− mice) of MVEV.wt, MVEV.C.IRES, or MVEV.IFN-β. Mice were monitored daily for a period of 28 days and morbidity and mortality were recorded. (C) At 2 days p.i., sera were collected from MVEV.C-IRES (n = 8)- and MVEV.IFN-β (n = 9)-infected IFNAR^−/− mice and viremia titers determined by plaque assay on Vero cells. Each symbol represents an individual mouse, and mean titers are indicated by a horizontal red line. The dotted line represents the detection limit of the plaque assay.