J亚群禽白血病病毒分离株的分离鉴定和全基因组测序分析OA

To investigate the infection status of avian leukosis(AL)in Hebei Province,suspected tumor-associated dead chickens were collected between 2023 and 2024 and screened for avian leukosis virus(ALV)by polymerase chain reaction(PCR).ALV-positive samples were inoculated into chicken embryo fibroblasts(CEF)for indirect immunofluorescence assay(IFA),viral subgroup identification,and chick infection experiments.The whole genome of the isolated strains was subsequently sequenced and analyzed.The results showed that 53 of the 63 samples were ALV-positive.Based on IFA and viral subgrouping,one ALV subgroup A(ALV-A)strain and fourteen ALV subgroup J(ALV-J)strains were obtained.A chick infection experiment identified one highly pathogenic ALV-J strain,designated HB.QHD.7.Genome sequencing and analysis revealed that the HB.QHD.7 isolate had a full-length genome of 7 535 bp,sharing 87.7%nucleotide identity with the UK prototype strain HPRS-103 and the highest identity(89.2%)with the Guangxi strain GX16ZS01.Phylogenetic analysis showed that HB.QHD.7 clustered within the same major branch as reference ALV-J strains,indicating a close evolutionary relationship.The envelope protein(env)gene of HB.QHD.7 showed the highest homology(89.2%)with the Yunnan strains YNJC2201 and YNXC2201.The surface glycoprotein 85(gp85)gene exhibited the highest homology(86.5%)with the Yunnan strains YNJC2201 and YNXC2202,and mutations were identified in variable region 1(vr1),hypervariable region 1(hr1),and hypervariable region 2(hr2).The 3 ′ long terminal repeat(3 ′-LTR)sequence showed the highest homology(69.1%)with the Guangxi strain GX14NN01.In addition,the 3′ untranslated region(3′UTR)lacked the rTM region,partially lacked the E element,and contained a continuous 10-nucleotide deletion in the U3 region.These findings indicate that ALV infection is a major cause of tumor diseases in breeder chickens in Hebei Province and that such infections are widespread.This study enriches the genetic and evolutionary data of ALV and provides valuable information for future research and the prevention and control of ALV in breeder flocks.