Isolation&Identiifcation Of Infectious Bursal Disease Virus Tianjin Wild Strains And Comprehensive Prevention&Treatment Of IBD

In order to understand the popular status of IBD in Tianjin area and to guid theprevention and treatment work, two hundred and twelve cases infected naturally from poultryfarms of9suburban counties in Tianjin were acted as researching items. It were diagnosedand registed by the disease diagnosis process, then summarized and analyzed. The resultsshowed that82.5%of the chicken had immune1to2times;11.8%of flocks appearedsecondary infection; the day of outbreak mainly concentrated in21-30days; the diseaseaccured in all seasons of a year but mainly from May to June and September to October;23.6%of them were mixed infection with bacteria and with other viruses; The problemsexisted in the process of prevention ang treatment included mainly immune programmeunreasonable, stress of management, comprehensive control defects.To further study the molecular characteristics of Tianjin strains, the theory basis whetherthere are super strain and variation strain in Tianjin was provided. Two strains of IBDV wereisolated from the flocks failed to vaccination in this paper, VP2hypervariable regions of637bp were amplified by RT-PCR. The restructuring plasmid PUMT-VP2was constructedand sequenced. And then, two Tianjin isolates were compared with homed and abroadstrains of IBDV, and also phylogenetic analysis was conducted. The results showed that thehomology of nucenotide between TJ-hg, TJ-jh strains and vvIBDV UK661, OKYM, HD-96,Harbin-1strains are above95%, and to Harbin-1and GX are above98%. Special aminoacidin high variant region from the isolates and very virulent strains are completely identical.There are close kinship between isolates and very virulent strains by phylogenetic analysis.Therefore, the two isolates are named preliminarily as very virulent strains.For preventing infectious bursal disease more effciently, IBD yolk antibody wasprepared by Tianjin strains as immune antigen and then the immune globulin liposomes wereprepared with liposomes as a carrier. The results show that: antibody titer is1:128withoutbacteria and no exogenous virus pollution; it can be conserved as long as6months in4℃.According to the existing problems in the prevention of IBD, comprehensive strategies ofIBD prevention and treatment in3aspects are recommed including reasonable immuneprogram, completely daily management and comprehensive treatment measures to IBD flocks.