Isolation, Identification And Biological Characterization Of Fowl Adenovirus Group â… 

Avian Adenovirus can be subdivided into three groups: group I, group II, group III. Group I includes the conventional adenovirus or fowl adenovirus (FAV1-12) isolated from chickens, ducks and goose, sharing a common group antigen. It has been found that birds were reinfected with the same strain after 8 week, eliciting a secondary response to produce neutralization antibodies, especially in mucous immunity, in spite of humoral antibody.In this study, fowl adenoviruses (FAV) distributions in flocks of chickens, ducks and geese were investigated by RT-PCR. The results show that FAV was extensively popular in chickens, geese and ducks, with the positive rate of 51.4%, 51.7%, and 17.3%, respectively. The ORF8 (open reading frame 8) and ITR (right terminal region) of the viruses were amplified, sequenced and analyzed for nine positive samples separately from chickens, ducks and geese. All sequences from nine isolates were 94.7%-99.9% homologous to that of FAVI when compared with those fragments of CELOV, FAVI-JS, but shared low nucleotide sequence homology to FAV-9 and EDSV.The biological characterization of FAVs isolates were further studied with technology of electron microscope, tissue culture and animal challenge. The results of these experiments showed that the virus particles are spheroidal, non-enveloped, and about 70-80nm in diameter and couldn't agglutinate the erythrocytes of chickens. The virus couldn't cause CPE in chicken embryo fibroblast cells (CEF), but cause typical CPE in chicken embryonic kidney cells (CEK). No gross lesions was observed in chicken embryo inoculated with the isolates.To evaluate the pathogenesis of isolated viruses, SPF chickens were inoculated with the FAVI-G24-0605 at 1-day-old by subcutaneous injection or oral way. The weight of body and some immune organs were detected post infection 10d, 20d, and 30d. The results showed that the inoculated chickens were all healthy with no gross lesions during the experiment.There were no serious effects to the body weight of SPF chickens. Most of tissue samples showed no histopathological changes except some minor lesions at the early stage, which was same the normal control chickens. These results indicate that FAVI-G24-0605 strain is nopathengen virus.