Characterization of fowl adenoviruses isolated from field outbreaks of hydropericardium syndrome in Punjab

Fowl adenovirus (FAV) isolates (LHPSV-2, 4, 6 and 7) obtained from field Outbreaks of hydropericardium syndrome (HPS) were characterized as serotype-4 of FAV using virus neutralization test. The pathogenicity of isolate LHPSV-7 was studied in experimental birds. Clinical disease appeared on 3 days post inoculation (DPI) of HPS isolate (LHPSV-7) in 3week-old disease free broiler chicks. In experimental birds 16.8% mortality was observed. The severity of disease was seen between 5 and 7 DPI. The dead and sacrificed birds showed characteristic hydropericardium with transparent, amber coloured fluid in the pericardial cavity. Characteristic pathological changes in liver included, necrotic hepatitis and intranuclear inclusion bodies in hepatocytes. The inclusions were also observed in kidneys, heart, spleen and pancreas at variable stages of infection. Microscopically, depletion of lymphoid cells was observed in bursa, thymus, spleen and caecal tonsils. FAV antigen was detected at 7, 13 and 21 DPI in plasma by antigen capture ELISA. Antibodies to FAV were detected in serum by AGPT and indirect ELISA from 7 DPI onwards. A high titre (GMT > 1:64) was seen first oil 3 DPI followed by a decrease in antibody titre, which again increased by 21 DPI (GMT > 1:53.81).