FIG. 2.

Growth characterization of recombinant CDVs produced in this study. (A) Schematic drawing of different recombinant viruses. The recombinant 5804PeH genome is drawn to scale. Black and white boxes represent open reading frames and UTRs, respectively. The genes are indicated by their corresponding abbreviations. The M-F region of the recombinant viruses is expanded below. The signal peptide coding region of the F gene (Fsp) is shaded gray. (B and C) Growth curves of the parental 5804PeH virus and the three recombinant viruses in VerodogSLAMtag cells expressed as titers of released (B) and cell-associated virus (C). Cells were infected at an MOI of 0.01, and samples were harvested daily for 5 days. Titers are expressed as TCID₅₀. The parental 5804PeH virus is represented by circles, 58utrMF-NP by triangles, 58utrMF-NPΔF₁₀₆ by squares, and 58ΔF₁₀₆ by diamonds. Error bars indicate standard deviations. (D) Syncytium formation in VerodogSLAMtag cells. Cells were infected at an MOI of 0.01 and overlaid with 0.5% methylcellulose. Photographs were taken at 72 h postinfection, using phase contrast (top panels) and fluorescence excitation (bottom panels) at a magnification of ×100.