FIG. 5.

Biological characterization of viruses. (A to D) Data were obtained from infections with vgp150Δ (squares), vgp150R (triangles), and parental wild-type virus (circles). All infections of mice (BALB/c female) were intranasal with 4 × 10⁵ PFU of virus. In all panels, where indicated, bars represent the standard deviation from the mean, and asterisks represent a statistically significant difference from the revertant value. (A) In vitro multistep growth curve comparing replication of viruses in BHK-21 cells (MOI of 0.01). Titers were determined for both cell-associated (▪ and ▴) and cell-free (□ and ▵) virus. The data are representative of two independent experiments, each performed in duplicate. (B) Virus replication in the lung. The data shown are the mean virus titers obtained from four mice per group at each time point. (C) Total spleen cell number within infected mice. The data are the mean cell numbers obtained from four infected mice per group at each time point. (D) Latently infected cells in the spleens of infected mice as determined by IC assay. The data from four mice per group are shown at each time point. No preformed infectious virus was detected in this assay (data not shown). (E) Data obtained from real-time quantitative PCR analysis of the amount of viral DNA present relative to the amount of cellular L8 gene DNA present in spleen samples at 14 days p.i. The data were compiled from three separate analyses of four individual mice infected with either vgp150Δ or vgp150R as indicated.