FIG. 7.

Long-term maintenance of MCMV-ΔM94 genome and protection, B6 mice were infected i.p. with 10⁵ TCID₅₀ MCMV-wt (wt) (n = 5) or MCMV-ΔM94 (ΔM94) (n = 6). Twelve months p.i. total DNA was extracted from lungs. (A) PCR analysis was performed, obtaining a specific 246-bp fragment of the polymerase gene M54. As controls DNA from lungs 5 days after infection with 10⁵ TCID₅₀ MCMV-wt [wt (acute)] (n = 5), PBS (1), no template (2), or the BAC plasmid pSM3fr (3) was used. MW, molecular weight marker. (B) Quantitative real-time PCR analysis was performed, and viral M54 gene copies per μg genomic DNA were calculated. Each symbol represents one individual mouse. Horizontal bars show the medians of the groups. Genome copy numbers of MCMV-wt (wt) and MCMV-ΔM94 (ΔM94) are not significantly different (P > 0.05). Both groups are significantly different from mice with acutely infected lungs [wt (acute)] (**, P < 0.01). DL, detection limit. (C and D) B6 mice (n = 5) were immunized i.p. with 10⁵ TCID₅₀ MCMV-wt (wt; solid symbols), MCMV-ΔM94 (ΔM94; open symbols), Δm01-17+m144-158-MCMV (ΔΔ; dark gray symbols), or PBS (light gray symbols). Virus preparations were UV irradiated before immunization (UV) as indicated. Challenge infection was applied i.v. 1 year after priming with 10⁶ PFU MCMV-wt. The plaque assay was performed 5 days after challenge in lungs (C) and 14 days after challenge in salivary glands (D). Horizontal bars show the medians of the groups. Each symbol represents one individual mouse.