FIG. 3.
Cultured embryo cells from IFNAR0/0 mice support the replication of BDV. (A) Cells from wild-type (triangles) and mutant (circles) mice were infected with BDV and passaged twice weekly at a splitting ratio of 1:3. After each cell passage, a sample of cells was subjected to indirect immunofluorescence analysis in order to determine the percentage of BDV antigen-positive cells. (B) BDV infection induces IFN in mouse embryo cells. Cells from mice carrying a functional version of the IFN-inducible Mx1 gene either were left uninfected (a) or were infected with BDV (b). The cultures were fixed at 72 h postinfection and stained for nuclear Mx1 protein using a specific antiserum.