Number of days of clinical signs (A) and growth performance (B) after challenge infection with PRV strain NIA-3. Pigs vaccinated with VR1012 (lane 1), VR-gB + VR-gD (lane 2), VR-gB + VR-gD with DDA (lane 3), SL-CD (lane 4), pUC18 (lane 5), VR-pIL12 (lane 6), or VR-p IFN-γ (lane 7) were challenge infected 6 weeks after the third vaccination. Clinical signs were recorded blindly for 14 days after infection. Growth performance during the first week after challenge was assessed by calculating the MRDG in body weight. For the duration of clinical signs, differences in group averages were tested by the nonparametric Kruskal-Wallis test. For the MRDG, differences in group averages were tested for statistical significance by a parametric one-way ANOVA. Significance levels were set at 95%. #, results significantly different from those for pigs vaccinated with VR-gB plus VR-gD alone (lane 2); *, results significantly different from those for the sham-vaccinated control pigs (lane 1).