Establishment of Experimental Infection Model of Duck Hemorrhagic Ovaritis

【Objective】 The objective of the study is to create an experimental infection model of Duck Hemorrhagic Ovaritis,study the disease characterization and provide an available model for developing vaccine and evaluating antiviral medicine.【Method】 The infected 196-day-old ducks were inoculated with 104 ELD50 of a DHOV isolate,DHOV-HB-F4,via a combination of intranasal,intraoral and intraocular inoculation method.Clinical signs were observed and recorded daily.At 5,7,9,21,28 and 34 day after inoculation,serum samples were taken,randomly selected and sacrificed for necropsy.Gross lesions were recorded and various tissues were collected for histological examination.Various tissues including ovaries,liver,brain,and spleen were collected for re-isolating virus.The method of fixed virus and diluted sera was used to detect the neutralizing antibody.【Result】The food consumption of infected ducks showed significant decrease(decreased by 80%) at 3,4,5 day post inoculation(DPI),recovered to 50% of normal intake at 6 DPI and to normal level at 11DPI.The egg production of infected ducks was significantly decreased at 3,4,5 DPI and zero at 6,7,8 DPI.The laying rate of infected ducks recovered to 60% of normal at 36 DPI and 80% at 39 DPI.DHO virus could be successfully re-isolated from three ducks' ovaries and liver on 5 DPI(3/3),two ducks' ovaries(2/2) and one duck's spleen and brain(1/2) on 7 DPI,one duck's ovaries(1/2) on 9 DPI.At 21 and 28 DPI,DHO virus could not be re-isolated from the infected ducks' tissues.The infected ducks showed ovary degeneration and deformation,follicle membrane hyperaemia and haemorrhagia;ovary,liver,brain and spleen characterized by the reticular cells hyperplasia which showed acute Hemorrhagic Ovaritis,interstitial hepatitis,nonpurulent meningoencephalitis,necrotizing splenitis,interstitial nephritis and mild myocarditis.The infected ducks only produced lower-titer neutralizing antibody on week 3 post inoculation.【Conclusion】The experimental ducks showed acute Hemorrhagic Ovaritis after infected by Duck Hemorrhagic Ovaritis.The experimental infection model of Duck Hemorrhagic Ovaritis was developed in Peking duck which could be a model for screening and evaluating the antiviral medicine and vaccine.