Research on technology of oil emulsion infectious bursal disease vaccine production.
2005
Toroqi, Reza | Bahmani Nezhad, Mohammad Ali | Shushtari, A`bd Ol-Hamid | Momayyez, Reza | Pur Bakhsh, Ali | Akhavi Zadegan, Mohammad Ali | Aqa`i Pur, Khosru | Haq Shenas, Gholam Reza
Highy virulent strains of infectious bursal disease virus (IBDV) emerged in Iran in 1991, devasting Irnian poultry industry. Total 12 IBD viruses were detected among the collected field samples by RT-PCR and confirmed to be very virulent IBD viruses by using PCR-RFLP technique. The viruses were isolated in SPF embryonated chicken eggs. Deduced amino acid sequence analysis of VP2 gene variable region of the viruses revealed that Iranian field isolates were similar to each other and highly virulent IBDV isolates repoted from Europe and Japan. None of the field isolates was found to be an antigenically variant or atypical highly virulent IBDV. Pathogenicity study in one of the isolates (IR499) showed 85% and 22% mortality rates among SPF and broiler chickens, respectively. Two inactivated IBD vaccines of embryo or burs of Fabricius origins using IR499 were prepared. The efficacy of the inactivated vaccines along with a commercial inactivated vaccine was determined by measuring both the antibody response of broiler breeder chickens and bursal protection of their progeny chicks. The bursa-derived IBD vaccine produced significant higher antibody titers in the vaccinated dams and better bursal protection in their progeny chicks in comparison to the other vaccines. Moreover, after vaccination of 10-day-old broiler chicks having maternal antibodies with the embryo-derived vaccine, two commercial inactivated IBD vaccines or combination of these vaccines with a live IBD vaccine and then challenge with IR499 three weeks later, all chicks were protected against clinical disease but not against bursal atrophy. However, no significant difference was found among the groups. It is concluded that the strain used in the inactivated IBD vaccine and the type of host used for propagation of the virus can influence the extent of protection against field virus in the offspring of vaccinated dams. This advantage was not observed for the vaccinated broiler chickens with maternal antibodies.
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