Pathological and electron microscopic studies in broiler chicks naturally infected with hydropericardium syndrome virus

An outbreak of hydropericardium syndrome was recorded in a private poultry farm in Haldwani area ofUttaranchal during January, 2002 with 80% mortality. The course of disease was 8–10 days. Post-mortem examination of dead birds revealed pale and enlarged liver with discrete or diffused necroticfoci. The kidneys were enlarged and congested having necroticfoci throughout. The accumulation of fluid in pericardial sac was invariably recorded in all the affected birds. Histopathological examination of liver revealed necrosis, karyorrhexis and infiltration with mononuclear cells. Isolated hepatocytes also showed distinct and large basophilic intranuclear inclusion bodies. By electron microscopy, intranuclear adenovirus like particles distributed in paracrystalline arrangement were demonstrated in hepatocytes. The virus was isolated in chicken embryo liver (CEL) cell culture from 20% (w/v) liver homogenate extract collected and prepared from infected birds. The cytopathic effects were characterised by cell rounding and degenerative changes within 24 hours. Isolated hepatocytes also showed presence of large basophilic intranuclear inclusion bodies, which were confirmed to be avian adenovirus specific by indirect immunofluorescence