Avian Leukosis Eradication And Whole Genome Sequences Analysis Of Avian Leukosis Virus Strains Isolated From Guangxi Black Chicken

Avian leukosis (AL) is an immunosuppressive tumor disease caused by avian leukosis virus (ALV). The main natural host of ALV is chicken. Although its morbidity and mortality rates are low, the productivity of chicken flocks will decline when it is infected with ALV, and then cause huge economic losses in aviculture. At present, the generally accepted effective methods of prevention and control of AL is to eradicate ALV from the Flocks. In Guangxi province, black chicken is one of characteristic local breeding with large scale. We selected two poultry-farms DGGX4and DGGX11in Guangxi to carry out the eradication of AL and related research.The first aim was to eradicate AL out of from black breeding chicken in two poultry-farms DGGX4and DGGX11. Applying commercialization ELISA detection kits of ALV p27antigen, A/B and J antibody to detect samples of anus swab/plasma (cock), egg white (hen) and serum collected from the poultry-farms. The chicken which antigen and antibody were positive will be eliminated. After eradication of the third generation, in DGGX4poultry-farm, the p27antigen positive rate of black breeding chicken was from12.4%down to0.52%, subgroup A/B and J antibody positive rates were0%, eradication effect was outstanding. After eradication of the fourth generation, In DGGX11poultry-farm, the p27antigen positive rate of black breeding chicken was from7.71%down to2.92%, in the third generation of eradication, total subgroup J and A/B antibody positive rates were7.61%and15.76%respectively, the result was favorable.The second aim was to sample serums or plasmas of the second eradication black chicken which p27antigen were positive and from DGGX4and DGGX11, inoculating DF-1cells for isolating and identifying ALV, and with methods of molecular clone and sequencing, planning to sequence the whole genome sequences of isolates, then analysis the homology between isolates and reference strains. The results show that the black chicken of DGGX4and DGGX11poultry-farms have been infected with ALV, and we have successfully isolated and identified two strains of ALV-J, respectively named GXD2and GXH3. The homology analysis results indicate that the amino acid homology of gpS5and gp37is above99%between GXD2and GXH3, the genetic distance of isolates is close to reference strain SD07LK1which from layer. The homology analysis results with reference strains indicate that the whole genome homology are above93.7%, The sequences of gag and pol are quite conservative; its homology is above94%. The variation of UTR sequences is larger,3’UTR is more variant than5’UTR. Both two isolates have complete E element.The study results indicate that the early eradication means of Guangxi black chicken were effective, and the method is feasible. At the same time, we have obtained two ALV-J strains isolated from black chicken, and completed the nucleic acid genome sequencing and analysis of Guangxi ALV-J isolates at first time.