The Molecular Epidemiology Of The Isolates Of Infectious Bursal Diseasevirus From Some Parts Of Henan Provinces

Abstract:Infectious bursal disease(IBD) is an acute, highly contagious viral infectious of young chickens caused by infectious bursal disease virus. Since the bursa of Fabficius is important organ to the maturatio of B-lymphoid cells, a mount of B cells in the lymphoid follicle of bursa Fabricius is lytic, atroph of bursa causing immunosuppression, leading to increased susceptibility to other pathogens and decrease immunological response to vaccine. In recent years, the emergence of vvIBDV and vIBDV, subtype diversity and antigenic variation that promote the new features of the incidence and prevalence of this disease and bring great economic losses to the poultry industry.In order to understand the molecular epidemiology of infectious bursal disease virus in Henan Province, we have been sequencing whole genome nucleotide sequence of HN-04strain. Then comparated and analyzed nucleotide and deduced amino acid sequences of HN-04strain to the representatives of IBDV strains in GenBank, and multi-the polyprotein VP2/VP4/VP3gene encoding amino acid hydrophilic and antigenic epitope were analyzed. This strain had the following characteristics:it had a conserved heptapeptide SWSARGS,222P,249Q,254G,these explained its antigenicity had not yet mutated and this strain didn’t belong to the variat strains;222P、242V、253H、279N、284T, these were fully consistent with the attenuated strains.The result of segment A nucleotide sequence and deduced amino acid sequence homology analysis was that HN-04had the high homology with the attenuated strains CEF94、Cu-1、Gt and the homology was99.5-99.9%,but it had the low homology with the very virulent strains HK46、UK661、Gx, the homology was95.6-95.9%. Evolutionary relationship, the HN-04strain belonged to a small branch and it had the closer relationship with attenuated CEF84、variant strain NB, but the distantly related with the very virulent strains HK46,、UK661、Gx and the classics strains T09, UPM94/273. Compared with serum type Ⅰ strains, HN-04strain had the low difference with CEF94,only one amino acid variation and the homology was99.8%, but it had the high difference with Edgar strain, a total of38amino acids variation. For the VP1gene nucleotide sequence and deduced amino acid sequence homology analysis,we found that the HN-04strain had the highest homology with the very virulent strains UK661and it had the low homology with the attenuated strains Cu-1, CEF94, B87, Edgar, Gt. Evolutionary relationship,HN-04neither belonged to the very virulent strains nor the attenuated strains, it formed a separate branch between them. So we speculated HN-04strain was a recombinant virus. These results provided the technical foundation for the molecular epidemiology, differential diagnosis and prevention research of Infectious Bursal Disease Virus in PuYang of Henan Province.