Figure 5.

Growth characteristics of parental and recombinant EHV-1 and EHV-4 in cell culture. ED cells were infected with the respective viruses at a multiplicity of infection (MOI) of 0.01. Means ± SD of diameters of 100 plaques measured for each virus are shown. The plaque diameter of parental viruses was set to 100%. No significant differences (one-way ANOVA; p > 0.05) between parental EHV-1 and EHV-1_gB4 were obvious (a). A significant reduction (one-way ANOVA; p < 0.05) of plaque size for EHV-4_gB1 was evident when compared to parental and revertant virus. Means ± SD of diameters of 100 plaques measured for each virus are shown. The plaque diameter of parental viruses was set to 100% (b). For single step growth kinetics of EHV-1 recombinant viruses, ED cells were infected at an MOI of 1 (c,d), followed by citrate treatment (pH = 3) to remove remaining extra-cellular virions. Infected cells (c) and supernatants (d) were separately collected and virus titers were determined at the indicated times post-infection (p.i). The data presented are means ± SD of three independent measurements. No significant differences were measured for the EHV-1 recombinant viruses when compared to the parental viruses (Friedman test-Dunn’s multiple comparison test; p > 0.05). (e) For multi-step growth kinetics of EHV-4_gB1, ED cells were infected at MOI of 0.01, followed by washing. Infected cells and supernatants were collected and virus titers were determined at the indicated times p.i. The data presented are means ± SD of three independent measurements. A significant decrease was measured for EHV-4_gB1 at several time points (*) when compared to the parental and revertant viruses (Friedman test–Dunn’s multiple comparison test; p < 0.05).