| "Hydrocardia-hepatitis syndrome" (HHS) is a new type of poultry disease caused by serotype 4 of aviadenovirus group (Fowl Adenovirus serotbe4, FAV 4). The typical symptoms is the sudden death of 3-5 weeks broilers, laying hens, the main features of which was pericardial accumulation yellow water or jelly like material, and accompanied with hepatomegaly, very brittle color light.The disease was first reported by Helmboldt in broilers of the United States in 1963, then Mexico, Canada, Japan, Australia and many other countries have reported the occurrence of this disease, indicating the extension of adenovirus infection. In 1976, Taiwan reported the disease for the first time, then Liaoning, Jilin, Hunan, Jiangsu and Henan Province also found the existence of the disease. The disease was reported in Angola of Turkey in 1987. Then Mexico reported the occurrence of the disease in 1989. After that Iraq, Peru, India, Chile, Russia and other places have been an outbreak of the disease. The disease in China has become a serious threat to the raising of poultry infectious diseases, bringing serious economic losses.Serotype 1, serotype 2 and serotype 8 of group I fowl Adenovirus have isolated in china. In order to explore the distribution, infection and pathogenicity of serotype group I fowl Adenovirus in the west of Hubei. In this experiment, group I fowl Adenovirus was isolated from chickens suspected hydropericardium hepatitis syndrome in different area from Hubei province. Firstly it were conducted to observe the pathological changes in the anatomy and collect the diseased tissues for pathological section. The livers were inoculated in the SPF embryo and then blind 3 passages, collect allantoic fluid DNA, amplify the isolated strains of hexon gene via PCR method. The serotype of FAV-4 was identified by the primers of isolated Adenovirus. The results showed in the pathogenesis of broiler and laying hens,3 strains of avian adenovirus were isolated. The results of sequeccing showed that the homology of the 3 strains was 100% and belong to the same strain.This study was conducted by sequence analysis of hexon gene of isolated strains. The sequencing results indicated that the virus shared 99.8% identity with FAV-4 in group I and shared 99.3% identity with China Agricultural University and 69.6%-98.4% identity with others serotypes, and 43.1%-78.6% identity with hemorrhagic enteritis in group Ⅱ and egg drop sydrom virus in group Ⅲ. These results confirmed that the isolated virus was a member of Fowl advenovirus in group Ⅰ.Homology comparison result is consistent with FAV-4 amplification primers. The amino acid homology of isolated strain was highest with the strain from Wuhan of Hubei. But, the amino acid was chenged in the site of 3,368 and 786 in hexon gene.The isolated strains was artificial infection in 40 day old SPF chickens by subcutaneous inoculation, meanwhile design the control group. Then the incidence and symptoms of chicken were observed in daily. Chickens in inoculation group were immediately found the incidence of death, then liver and other organs were collected to fixed sections, HE staining. The results showed that after inoculation of group I fowl Adenovirus, the chicken appeared depression, loss of appetite, drooping wings, legs squat, corner, curled feathers unkempt, individual pull yellow green stool. During the whole experiment, the mortality rate reached 60%. The results of chickens anatomical lesions showed a visible pericardial effusion, the accumulation of a large number of yellow liquid, yellow dye. The liver appears obvious bleeding spot and speckle, part of chicken show yellow kidney enlargement, with urate deposition, muscular stomach swelling, but no bleeding. The chicken, not death in the experimental, was without pericardial effusion, liver individual scattered bleeding points. The liver and heart was normal in the control group without lesions. PCR detection methods are applied to verify, test group of chicken only and the experimental group challenged without killing the chicken to only appeared to bands, while the control group did not strip produced that attack in the toxic group not infected chicken only a latent infection, control group chicken only normal. |
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