In Ovo Vaccination against Avian Influenza Virus Subtype H9N2

Due to the major occurrence of infection by avian influenza virus (aiv) subtype h9n2 in broilers and broiler breeders at first 2-3 weeks of age in this country,where the virus is endemic since 1999,it has become necessary to devise new strategies for better protection of chicks at early age. in ovo vaccination is one of the approaches for providing neonatal resistance against various infectious diseases in chickens. the aim of this study was to develop in ovo vaccine against h9n2 serotype of aiv. for this purpose a vaccine strain of aiv h9n2 was used to develop both inactivated and live virus vaccines for experimentally inoculating18- day old embryos. in addition to this two other groups of chicken were separately vaccinated with both inactivated oil-emulsion and live virus vaccines of h9n2 for comparison. the hatched chicks were monitored for the development of hi antibody response against aiv h9n2. all these birds were later challenged with field isolate of aiv h9n2. the results indicated that in ovo live aiv h9n2 vaccine produced higher antibody response at younger age and showed better protection upon challenge. © 2015 pvj.