FIG. 7.

Infection of neonatal BALB/c mice with hMCMV-ES.Ap1, parental, and revertant viruses. (A) Virulence of hMCMV-ES.Ap1 in newborn mice. Groups of 4 to 11 3-day-old BALB/c mice were i.p. inoculated with increasing doses of parental hMCMV-ES, hMCMV-ES.Ap1, and hMCMV-ES.Ap1-rev. Animals were monitored daily for survival, and the corresponding LD₅₀ was calculated as indicated in Materials and Methods. (B) Growth kinetics of hMCMV-ES.Ap1 in the newborn mice. Three-day-old BALB/c mice were i.p. inoculated with 5 × 10⁴ PFU of hMCMV-ES, hMCMV-ES.Ap1, or MCMVdE. Animals were sacrificed at the indicated times after infection, and viral titers from selected organs were determined. Horizontal bars indicate the median values. The dashed lines indicate the limit of detection of the assay. The observed differences did not reach statistical difference (P > 0.05) as determined by the Mann-Whitney test (two-tailed).