isolation, characterization and standardization of new infectious bursal disease virus for development of a live vaccine

background and aims: infectious bursal disease (ibd) is an acute contagious viral disease of birds worldwide. the causative virus induces a persistent immune suppression following destroy b lymphocytes precursors in bursal lymphoid follicles. vaccination is the main strategy for prevention of the disease in commercial poultry industry. materials and methods: to produce a live vaccine against the disease, an new virus strain was isolated from the affected bursa of fabricius. diagnostic serological tests, histopathology and molecular examinations were done for pathotyping the isolate. results: the results indicated that the virus is a new strain and named ibd07ir. in case of developing live ibd vaccine, the bacteriology, purity, titration, reversion to virulence, bursa-body index, immunosupression and efficacy tests were performed on the candidate vaccine virus seed. the live vaccine was produced following propagation of the ibdv seed in spf embryonated eggs. the proper dose of the vaccine was found by administration of spf chicken groups. afterward, the laboratory trial was scaled and the clinical trials were done three times with different administration routs. conclusion: according to serological assays and challenge, the developed live ibd vaccine induces an adequate immunity in both spf and commercial chickens and had no adverse effects.