Diagnosis Of Hydropericardium-Hepatitis Syndrome And Isolation & Identification Of FAV-4 Tianjin Strain

Fowl Hydropericardium-hepatitis syndrome occurred firstly in Ankara of Pakistan and Fowl Adenovirus (FAV) was the predominant pathogens. Fowl Adenovirus is widely distributed in nature, divided into three groups, and 12 serotypes, 5 genotypes in FAV-I caused many different diseases by horizontal and vertical transmission. Fowl Adenovirus is non-enveloped double stranded DNA virus with consist of pentamer, hexon and fibres protein.It can be detected by electron microscopy, serology, molecular biology and other methods.The vaccine has been developed for the disease In recent years, but not commercialized.Strengthen husbandry and management are being main control measures.For understanding Hydropericardium-hepatitis syndrome (HHS) in Tianjin and doing good job for controls, systemic diagnoses were in progress by epidemiological investigation,gross lesion examination, bacteriological tests, histopathological observation, PCR examination and regression test with 40 day-old sick pullets on a chicken farm in Tianjin area.The results showed that chickens were onset & dead suddenly in a flock, hydropericardium and hepatomegaly were main changes grossly, bacterial cultures were negative, congestion &edema in liver, many intranuclear basophilic inclusion bodies in hepatocytes observed under microscope in tissue sections, PCR on FAV-4 was positive and regression test was consistent with natural sisease. Fowl Hydropericardium-hepatitis syndrome was diagnosed finally caused by FAV infection.In order to investigate HHS pathogen in Tianjin area, the molecular characteristics were studied. A strain of FAV was isolated from liver of natural infected pullet and named as TJ1607. The isolate was subjected to amplify a 655bp fragment from the hexon gene by PCR,recombinant plasmids constructed were sequence and homology analyses were proceeded by MegAlign. The results showed that the homology of TJ1607 isolate to FAV-C in China was 98.3%, to FAV-4 in India & Canada were above 97%, and to other serotype FAV were 73.2%-48.4%. The phylogenetic relationship of the isolates can be obtained from the phylogenetic tree analysis chart, which is close to FAV-4; So, the rusults indicate that this pathogen caused HHS in tianjin area is FAV-4 named TJ1607.To better understand the occurrence,development and prognosis, theoretical bases were provided for reasonable measures of diseases prevention and control. One hundred 3-day-old chicks were divided into 5 groups as group 1-3 as experiment groups, group 4 as control and group 5 as necropsy.The disease was copied by oral inoculation with the isolated strains,symptoms, incidence, histopathological examination, PCR, agar diffusion test were recorded.The results showed that chicks began to sick on third day post-noculation with malaise,lethargy, loose stools of pale yellow and other symptoms, the first 3-4 days of death, the death peak on day 4-5 for 5 days, no longer dead appeared after eight days, the average mortality was 36%. The results of the experimental group were consistent with the clinical cases, so as to provide a theoretical basis for the study of pathogenicity.