The Diagnosis and Molecular Epidemiology Investigation of Avian Hepatitis E in Shandong Province, China

Background: Avian hepatitis E virus (HEV) is the pathogenic agent of big liver and spleen disease (BLS) and hepatitis-splenomegaly syndrome (HS) in chickens, which has caused economic losses to the poultry industry in China. Eighteen samples of BLS chickens were collected in this study to understand the molecular epidemiology characteristics of avian HEV in Shandong province, China.Results: Gross and microscopic lesions of clinical samples were observed, then virology detection and genetic analysis of avian HEV were performed. The results showed that there were significant swelling and rupture in the liver, and spleen was enlarged. Microscopic lesions demonstrated that obvious hemorrhage in the liver, with infiltration of heterophilic granulocytes, lymphocytes, and macrophages, the reduction of lymphocytes in the spleen. Eleven out of the 18 samples were positive for HEV, with a positive rate of 61.11%. More importantly, all HEV positive samples were mixed infections. Among them, the mixed infections of avian HEV and chicken infectious anaemia virus (CIAV) and fowl adenovirus (FAdV) were the most common. In addition, the genetic evolution analysis showed that all obtained HEV isolates did not belong to the reported 4 genotypes, and they constituted a novel genotype. Conclusions: These results of this study further enriched the epidemiological data of avian HEV in Shandong province and proved the genetic diversity of HEV in China, but also uncovered the complicated mixed infections of avian HEV in clinical.