Isolation And Identification Of Field IBDV And Study On It's Pathogenicity

Infectious bursal disease (IBD) is an acute and highly contagious chicken and turkey infectious disease, which was caused by infectious bursal disease virus (IBDV). It was once controlled by use of vaccine before the late 1980s. But the emergence of variant IBDV and very virulent IBDV (vvIBDV) has changed epidemiology of IBD, which could infect the inoculated chickens. Classical IBDV, variant IBDV and vvIBDV coexisted in China, which makes it more difficult to vaccination. Only if the the immunogenicl character and pathogenicity are ascertained, can the vaccination be successful. Based on the prevalence condition of IBDV in Shandong Province in recent years, the following studies have been carried out:Test 1, some strains IBDV were isolated in inoculated chickens from Shandong province. According to the epidemiology and clinic symptom of infected chickens, virus isolation, results of tissue pathology, AGID, three strains of IBDV had been isolated and identified. They were named as IBDV SD01,IBDV SD02 and IBDV SD03 respectively.Test 2,the sequence of VP2 hypervariable region was coloned and analyzed to learn it's immunogenicl character. The results showed that all the field strains had the known molecule character of vvIBDV in VP2 gene, which caused the inoculated chickns ill. They showed that the prevalent strains are translating into vvIBDV partially under the immune pressure.Test 3,The test of pathogenicity on 3-6-week-old SPF chickens indicated that all the three isolated field strains had high pathogenicity and they could be called vvIBDV according to the prevalent theory. The vaccine of low virulence can't protect the chicken when it was infected by vv IBDV. Keywords: Chicken;IBDV; Isolation and Identification;Pathogenicity...