Isolation And Identification Of Avian Adenovirus Type 4 Subgroup ? And Development And Application Of Yolk Antibody

Hydropericardium syndrome?HPS?,also known as Angara disease?AD?,is a highly contagious and pathogenic infectious disease caused by the subgroup of Fowl Adenovirus serotype 4?FadV-4?,which is the main characteristic of pericardial effusion.Since 2014,the disease has gradually spread from the coastal areas such as Shandong,Jiangsu,Guangdong and other coastal areas in China,such as Hebei,Henan,Shanxi,Anhui,Hubei and other inland provinces.It has caused great economic losses to poultry industry in China.In this study,we isolated a virus,and identified the strain as FadV-4.We made oil emulsion inactivated vaccine and high level yolk antibody by using the isolated strain,and the clinical experimental results were evaluated.The following results are obtained:?1?The FadV-4 specific primers were used for PCR detection.The results were positive and confirmed to be Ankara disease virus.?2?The epidemic materials was treated and then injected into SPF chick embryo,which could cause the regular death of the chick embryo and the typical pathological changes of the pericardial effusion.The ELD₅₀ was 10^-6.78/0.1 mL.The coagulation test was negative.The specific primer of Hexon gene was used for virus gene sequencing of isolated strains,and it was 98.7%⁹9.8%homology with Hexon gene sequence of serum type 4?subgroup.of fowl adenovirus in GenBank.Then,the virus of isolated strains were used to SPF chickens,and caused the typical clinical symptoms and pathological changes of FadV-4infection in chickens.?3?The inactivated vaccine of oil emulsion was prepared with the fadv-4 isolator?SD strain?.The antibody growth rule test showed that after 0.2 mL and 0.5 mL doses vaccinate in SPF chickens,the antibody level showed a rapid rise,followed by a slow decline and maintenance of a certain level.The immune attack protection test showed that the antibody titer of the 0.2 mL dose could reach 4.40log2 at 21 days after immunization,and could fully protect the attack of Fad V-4 strong virus strains,with a protective rate to 100%.?4?Fadv-4?SD strain?yolk antibody was prepared by multiple immunization with inactivated FadV-4?SD strain?oil emulsion vaccine.Agar-agar diffusion test showed that the antibody titer?log2?was 6 log2,which had good safety and protective effect on SPF chickens.The clinical application test showed that the protective rate of this yolk antibody against the infection of FadV-4 in broilers was up to 98.67%,and the curative rate of FadV-4 in broilers was up to 97.33%.In conclusion,a FadV-4 isolator was obtained and the sequence analysis of Hexon gene was completed,providing data for the molecular epidemiology and a basis for research on the pathogenesis and pathogenesis of FadV-4.The inactivated FadV-4?SD strain?oil emulsion vaccine prepared from isolated strains has good safety and immunogenicity.FadV-4?SD strain?of oil emulsion inactivated vaccine preparation of egg yolk antibody has a good effect of prevention and treatment the infection of FadV-4 in clinical.It can be used for disease prevention and treatment of chicken Angara,and provides a technical method of comprehensive prevention for our country chicken Angara disease.