Figure 6.

Comparison of the capacity for virulence, replication and shedding between chicken and wild bird isolates. Excerpts from Figures 1 and 3 in Ferreira, H.L.; Taylor, T.L.; Dimitrov, K.M.; Sabra, M.; Afonso, C.L.; Suarez, D.L. Virulent Newcastle disease viruses from the chicken origin are more pathogenic and transmissible to chickens than viruses normally maintained in wild birds [55]. (A) Survival curves of directly inoculated birds. Chickens were separated into 3 groups for each virus and inoculated with a low, medium, and high dose of the five NDV strains (PE08, EG11, TZ12, CO10, PI13). Mortality in each experimental group was followed daily over 14 days. No common letters indicate significant differences (p < 0.5). (B) Virus shedding is directly inoculated birds after inoculation with chicken- and wild bird-origin NDV. NDV titers were estimated in both oropharyngeal (OP) or cloacal swab (CL) swabs of directly inoculated birds with three different doses of NDV strains at 2, 4, and 7 DPI. The detection limit of the different RRT-PCR assays targeting the NDV strains varied between 1.5 and 1.7 log10EID50/mL and are shown as dotted lines on the Y-axis. Mean and standard deviation of the mean for positive swabs at each time point are shown as bars. No common letters (A or B) differ significantly (p < 0.05) when comparing oropharyngeal or cloacal swab samples from the different viruses with the same infectious dose and same sampling point. Non-detected swabs were added below the limit of detection for each virus.