Lsolation And Identification And Study On Pathogenicity Of Fowl Adenovirus-I

Inclusion body hepatitis (IBH) is to disoperate the livers and form intranuclear inclusionin the liver cells caused by some serotypes of Fowl Adenovirus-I(FAV-I). It was firstdetected in the1963in America and is now widely distributed in many countries worldwide.It was first described in Taiwan in1976. Subsequently the report of IBH increasedgradually.This disease was firstly reported in Shandong province, China in1988, and prevailsevery year. Fowl Adenovirus-I can cause severe immune suppression which results in poor orfailure of the immune effects, and causes substantial loss in the poultry industry.Serotype I, serotype II and serotype VIII of FAV-I were isolated in China. In this study,FAV-I was isolated from suspected infection in Shandong province. Serotypes of isolatedIBH strains were determined by chick embryo pathological change, amplification of hexongene and AGP test.. Eight strains were isolated. The specific fragment was amplified from allisolates. Three serotypes were identified, two serotype I strains, three serotype VIII strainsand four serotype X strains.SPF chicks were experimentally inoculated with one FAV-I, serotype X throughsubcutaneous injection route to observe incidence and clinical symptoms.The chicks ofexperimental group and the negative control group were sacrificed randomly after infection atpresetted times. The heart, liver, lungs and intestine were collected,fixed and stained byconventional H.E. staining. Then the pathological changes of these organs were observed,and hematological and biochemical parameters were evaluated. The chicks showed depression,poor appetite, drowsiness and other symptoms after inoculation. Histopathological changeswere characterized by fatty degeneration, extensive hemorrhage and inflammatory cellsinfiltration in the liver, basophilia inclusion body in the liver cells, shedding of intestinalvillus in the duodenum, catholicity hemorrhage in the lungs.The level of HGB, WBC, RBC,BUN, and AST significantly changed.To obtain the primary antibody, New Zealand rabbits were immunized with the purifiedFAV-Ito obtain FAV-I specific antibody which were then extracted by thecaprylic-ammonium sulphate method, purified through Sephadex G-200.An indirect IFA forrapid diagnosis of FAV-I was established with FITC-labeled-secondary antibody underoptimum conditions. The optimum conditions of this IFA were as follows: dilute the primaryantibody (1:25) and incubated at4°C overnight; and then incubated at37°C for1h withdiluted FITC-labeled-secondary antibody (1:200), and specific bright yellow green flurescenewas observed as positive signal of presence of FAV-I. We detected the organs by IFA from the experimentally infected chicks, the stronger positive signals could be detected in intestineand liver which was considered to be target organs of FAV-I. The IFA established in thisstudy had been demonstrated to be a rapid, sensitive, specific and economical test fordiagnosis and antigen location of FAV-I.