FIG. 3.
MCMV-ΔM94 induces neutralizing antibodies and T-cell responses. (A) B6 mice were immunized i.p. with 105 TCID50 MCMV-wt (wt) or MCMV-ΔM94 (ΔM94) or mock infected (PBS). Blood was collected 12 weeks p.i., and virus-neutralizing capacity of the serum was determined using MCMV-luc. Neutralizing antibody (ab) levels of MCMV-ΔM94-immunized mice were significantly lower than antibody levels of MCMV-wt-immunized mice by two-way ANOVA testing (P = 0.04). Values represent the means plus SD of measured serum pools. RLU, relative luciferase units; BG, background. (B) After adoptive transfer of 3 × 105 OT-I CD8+ T cells (top), B6 mice (n = 5) were infected i.p. with 105 TCID50 MCMV-ova (wt-ova) or MCMV-ova-ΔM94 (ΔM94-ova) or injected with PBS. At days 3, 6, and 8 p.i. flow cytometric analysis was performed on blood for the congenic marker CD45.1 and CD8. After adoptive transfer of 3 × 105 OT-II CD4+ T cells (bottom), B6 mice (n = 5) were infected i.p. as above. At days 3, 6, and 8 p.i. flow cytometric analysis was done on splenocytes for CD90.1 and CD4. Each bar represents the mean plus SD for the indicated group (**, P < 0.01). spec, specific. (C) B6 mice (n = 5) were infected i.p. with 105 TCID50 MCMV-wt (wt), MCMV-ΔM94 (ΔM94), or UV-irradiated MCMV-wt (wt UV). At day 6 p.i. an in vivo cytotoxicity assay was performed using splenocytes labeled with carboxyfluorescein succinimidyl ester (CFSE) and the indicated viral peptides. Symbols represent the specific lysis activity against the indicated peptide in individual animals. The cross bars indicate the medians of the analyzed groups. The right panel shows an exemplary set of flow cytometric data.