Investigation Of FadV-4 Infection In Wild Birds In Liaoning And Its Penton Gene Sequence Analysis

Group I avian adenovirus serotype 4(FAdV-4)causes Ankara disease,namely hydropericardium Hepatitis syndrome(HHS),with hepatitis and pericardial effusion as the main features,the main infection is 3-6 weeks old chicks.Once infected,the mortality rate can reach 80%.Avian adenovirus belongs to the adenovirus family of avian adenovirus.According to its antigenicity,it can be divided into three groups.The group avian adenovirus contains 5 genotypes(A-E),12 serotypes,and FAdV-4 belongs to I group of avian adenovirus type C.With the increasing reports of poultry FAdV-4 infection,reports of wild bird infection with FAdV-4 have also appeared,but the infection and prevalence of FAdV-4 in wild birds is still unclear.In this experiment,the infection of wild bird FAdV-4 was detected by PCR,and the sequence of FAdV-4 penton gene was analyzed.The prevalence of FAdV-4 in diseased wild birds in Liaoning Province was understood on basically,the genetic evolution of the Penton gene was mastered.In this experiment,38 species of wild birds with different types of sudden death and death were collected from various parts of Liaoning Province.The liver was collected,the genome was extracted,and the infection of FAdV-4 in the dead wild bird was investigated by PCR.Among them,29 positive samples were detected,and the positive rate of FAdV-4 infection in the dead wild birds was as high as 76.32%.The Penton primer was used to detect the liver of the dead wild bird,and the genome was extracted.The Penton gene was amplified by PCR,and the T vector was ligated to transform the competent cells.The Penton gene was cloned and sequenced.A total of 8 strains of Penton-T vectors were constructed in this experiment.These 8 strains were derived from different breeds of wild birds.The sequencing results showed that the Penton gene length of 8 strains was 1578 bp.Analyzed the homology of nucleotide sequence and amino acid sequence,then predicted the epitope of Penton protein.Nucleotide homology analysis showed that the Penton gene of these 8 viruses shared 99.4-99.9% homology with group I avian adenovirus type C(serum type 4)in Gen Bank,and the homology relationship was the closest;The homology with domestic FAdV-4 representative strain is 99.6-99.9%,and the homology with foreign countries is 98.4-99.7% in Gen Bank,the homology with domestic FAdV-4 is the closest.The nucleotide variation sites are mainly concentrated in 4 places,the 772 th position is changed from G to A(G?A),the 826 th A?G,the 956 th A?G,and the 1543 th G?A.Among them,the Penton genes of 6 strains all mutated at these 4 nucleotide positions,which were significantly different from other reported strains,and represented the recent epidemic trend of FAdV-4 in wild birds in Liaoning Province.The amino acid homology analysis of the Penton protein with group I avian adenovirus type C(serum type 4)in GenBank showed that the homology was 98.1%-99.4%,and the epitope of the amino acid mutation site was analyzed.The 258 G?S antigen index was 0.46?0.55,and the 276 th S?G antigen index was 0.45?0.35.The change of antigen index has certain reference value for the development of vaccine and the selection of popular strains.In summary,the positive infection rate of FAdV-4 in wild birds in Liaoning Province is as high as 76.32%.The prevalence strain of wild bird FAdV-4 has specific mutation sites compared with the epidemic strains of poultry.This experiment laid the foundation for further study on the virulence,pathogenicity and vaccine development of FAdV-4 in wild birds.