Protective efficacy of rHVT-pmpD-N and parental HVT against challenge with very virulent MDV strain RB-1B.

a Twenty-five 1-day-old SPF chickens in the rHVT-pmpD-N group were immunized with 8000 PFUs of rHVT-pmpD-N, while 20 SPF chickens in parental HVT group were immunized with 8000 PFUs of parental HVT (recovered from BAC-clone). A total of 20 chickens in the CEF control group were inoculated with uninfected CEF (1.3 × 105 cells per dose) as the negative control. Seven days after immunization, 10 chickens from each group were inoculated intraperitoneally with a virulent strain of MDV RB-1B (1000 PFUs/chicken) and then monitored for 60 days.Protective efficacy of rHVT-pmpD-N and parental HVT against challenge with very virulent MDV strain RB-1B.