Fig 4. NDV Experiments in SPF chickens.

(A) Mean levels of antibody against NDV in serum. Levels of antibody against NDV in serum were determined using a commercially available ELISA kit after three weeks post vaccination. The cut-off value was presented as dot line. Statistical significance was determined by ANOVA with the Tukey-Kramer post hoc test. ***, P < 0.001; **, P < 0.01 (B) Survival curve after lethal NDV challenge. Three weeks after immunization, SPF chickens were intramuscularly infected with a lethal dose of KR-005/00 strain NDV. The chickens were observed daily for a period of 14 days for survival. (C) HI titers after two weeks post challenge for DIVA: Serum samples were analyzed with the standard HI test for the presence of HI antibodies against the La Sota NDV strain. Error bars represent standard deviations. ***, P < 0.001,