Infection Status and Epidemic Characteristics of Avain Leukosis Virus in Liangfenghua Breeding Chicken in Henan Province from 2021 to 2022

WANG Rudu; DENG Zuliying; QIAO Hongxing; ZHANG Han; BIAN Chuanzhou; LUO Jun; PENG Zhifeng

doi:10.15933/j.cnki.1004-3268.2025.02.016

Abstract：In order to explore the infection status and epidemic characteristics of avian leukosis virus(ALV)in Liangfenghua breeding chicken in Henan Province,ALV-p27 antigen was detected in 1 342 semen,1 611 cloacal swabs,8 187 eggs and 284 meconium collected from six cities of Henan Province in 2021-2022 by ELISA method.Meanwhile,512 hen serum samples were detected for ALV-A/B and ALV-J antibodies by ELISA method,and ALV was isolated from meconium by DF-1 cells.The gp85 gene fragment of the isolated strain was amplified by polymerase chain reaction(PCR)and sequenced.The gene sequences were compared with different strains of ALV-J,and the genetic evolution was analyzed.The results showed that the positive rates of ALV-p27 antigen were 13.11%(176/1 342),7.70%(124/1 611),2.39%(196/8 187)and 2.81%(8/284)in semen,cloacal swabs,eggs and meconium,respectively.The positive rates of ALV-A/B and ALV-J subgroups were 16.60%(85/512)and 15.23%(78/512)in hen serum,respectively.In addition,there was no obviously difference in the positive rate of ALV in Liangfenghua breeding chicken in six cities in Henan Province,among which Anyang City was the highest(4.90%,82/1 675),the lowest level was found in Shangqiu City(3.56%,64/1 798),indicating that ALV infection was found in Liangfenghua breeding chicken in different areas of Henan Province.The positive rates of ALV-p27 were 4.00%(4/100)in cloacal swabs,1.08%(1/92)in eggs and 1.15%(1/87)in meconium,suggesting that ALV infection was caused by both vertical and horizontal transmission,and it was more objective to evaluate the vertical transmission of ALV in breeder flocks based on ALV infection in breeding eggs.An ALV-J strain HN2022 was isolated,which was in the same evolutionary branch as reference strains HLJ09MDJ-1,HuB09-1,SX090912J,CAUHM01 and HPRS103.The nucleotide homology and amino acid homology of gp85 gene of different strains of ALV-J were 92.7%—97.8%and 88.6%—91.8%,respectively.The results of homology comparison of amino acids encoded by gp85 gene showed that the variation of amino acids encoded by gp85 gene mainly occurred in the high-frequency variation regions of sequence Hr 1 and Hr 2.The results not only showed that ALV infection was common in Liangfenghua breeding chicken in Henan Province,but also enriched the data of genetic variation characteristics of ALV,which provided data support for the subsequent study of the virus and the purification of avian leukemia in this chick.