Newcastle disease virus (NDV) outbreaks have been reported worldwide in
vaccinated and non-vaccinated chicken farms, causing severe economic losses despite
extensive vaccination. This study assessed the effectiveness of recombinant herpes virus of
turkey (rHVT-ND-IBD) expressing the F protein of genotype VII with conventional
genotype II vaccines against velogenic NDV genotype VII.1. 1. in broilers. Live ND vaccine
with inactivated vaccine (G1), live ND vaccine with rHVT-ND-IBD vector vaccine and
inactivated vaccine (G2), live ND vaccine with rHVT-ND-IBD vector vaccine (G3) and Live
ND vaccine alone (G4) were the four immunization programs that were employed. Along
with the control non-vaccinated group (G5). Birds were challenged at day 28. Clinical
protection, seroconversion, histological alterations, and viral shedding following challenge
were used to evaluate protection. The results showed mild clinical signs in G2 and G3 than
in other groups, In addition, the mortality rates were 15%, 0%, 0% and 42.5% in G1, G2, G3
and G4, respectively, vs 85% in G5. Moreover, the tracheal virus shedding in G2 and G3 was
significantly (p ≤ 0.01) reduced when compared with G1, G4 and G5. The mean lesion score
(MLS) was significantly (p ≤ 0.01) decreased in G2 and G3 compared to other groups. The
conclusion was that broilers immunized with rHVT-IBD-ND and NDV genotype II
vaccinations exhibited full clinical protection against NDV genotype VII.1.1. After that, it is
advised to give broilers rHVT-IBD-ND together with NDV genotype II vaccines to achieve
the best possible clinical protection against genotype VII.1.1, particularly in endemic
nations.