Interaction of Newcastle disease vaccine on serum response induced by avian infectious laryngotracheitis vaccine

Infectious Larangotracheitis (ILT) is an important economic disease of the respiratory tract in chickens. The highly contagious disease is caused by Gallid alphaherpesvirus 1 (GaHV-1). This study aimed to investigate the effects of Newcastle disease vaccine on the laryngotracheitis vaccine. Therefore a total number of 125 twenty-seven days old LSL commercial pullet randomly divided into five groups and kept in the separate rooms at standard temperature. Then according to a special program, they were vaccinated with Newcastle disease and infectious laryngotracheitis vaccines. Three weeks after vaccination, the serums were tested by hemagglutination inhibition (HI) test for Newcastle disease and ELISA for infectious laryngotracheitis. The results of this study showed that the titer of infectious laryngotracheitis (1990 ± 631) in a group (G4) that received the Newcastle disease vaccine first and the infectious laryngotracheitis vaccine three days later was more significant than other groups (P > 0.05). Newcastle titer (5.1 ± 1.45) was non significantly lower in this group than in other groups. Also, Newcastle disease titer was non significantly higher in the group (G2) that first received the ILT vaccine (P > 0.05). The results of this study showed a positive effect of Newcastle disease vaccine if used before the laryngotracheitis vaccine. The results of this study showed that it is better not to use these two vaccines together and to get a higher titer, it is better to use a Newcastle vaccine before the laryngotracheitis vaccine. It is recommended that to study other live vaccines and their interactions.