Immunosuppressive Properties of Infectious Bronchitis Vaccine4/91 strain against different programs and method of vaccination against Newcastle disease in Broilers

Abstract

Infectious bronchitis virus (IBV) primarily induces a respiratory disease in broilerscausing important economic losses in poultry industry. The aim of this study was to investigatethe immunosuppressive properties of live IB vaccine on the different programs and method ofvaccination against Newcastle disease (ND) in broilers. A total of 125 one-day-old broilerchicks were assigned into five equal groups. At day one G1 and G2groupswere vaccinated witha live (ND, IB)vaccine by dipping the head in the vaccine and intra-cloacae methodrespectively. Afterward, G3and G4 groups were vaccinated with a live ND vaccine alone by thesame method of G1 and G2. At the same time all these4 groups were vaccinated bysubcutaneous injection (S/C) with inactivated oil based vaccine ND. The G5 group was leftwithout vaccination as a control group. After that, all treated groups were vaccinated with a liveND by spray method at day 10 of the age. The immunosuppressive effects of this IB virus wasevaluated by Haemagglutination inhibition test (HI), and challenged by virulent ND virus.Bursa and Spleen indices were estimated in all groups. The results showed that the antibodytiters against ND was higher (P<0.05) in G3and G4 in compared with G1, G2 and controlgroups at 20 and 30 days of age. However, there was no significant difference of bursa indexand spleen index in all groups. Challenge test showed no mortality in the 3rd group while 10%in the 4th group, 85% in the 1st group and 90% in the 2nd group. In conclusion, it’s revealed thatthe best method and program of vaccination which can protect against ND was applied in the3rd group.