Figure 1
Restoration of the Mck2 open reading frame (ORF) changes mouse cytomegalovirus (MCMV) pathogenicity. (a) Schematic representation of the prototypic orientation of the MCMV genome, with the m131 and m129 ORF depicted below (in reverse orientation). MCMV-3D carries the same deletion of an AT base pair at position 187,786 disrupting the Mck2 ORF as described.19 Reinsertion of this base pair allows full-length MCK2 synthesis in MCMV-3DR. (b) Growth of MCMV mutants on murine embryonic fibroblasts upon infection with a multiplicity of infection (MOI) of 0.1. The titers of infectious virus in cell culture supernatants at the designated days post infection were determined by plaque assay with data points representing the mean of triplicate cultures. A representative result of two independent experiments is shown. (c–e) Neonatal mice were laryngopharyngeally infected with 5 × 104 PFUs MCMV mutants as indicated and (c) monitored for body weight gain. (d) Survival curve after MCMV infection. Animals fulfilling the termination criteria were killed. Data were obtained from four independent experiments with n=16 (MCMV-3D) and n=20 (MCMV-3DR). (e) Viral activity in neonatal organs estimated by the measurement of luciferase activity at time points after infection as indicated. Each value represents one animal, connecting line between medians. Data from MCMV-3D-infected neonates (lung) were in part already published in Stahl et al.9 MCK2, MCMV-encoded chemokine 2; PFU, plaque-forming units; RLU, relative light units. Statistical significance depicted as follows: *P<0.05; **P<0.01; and ***P<0.001.
