Abstract

The pathogenicity of recent field isolate of Avian Adenovirus Serotype IV (AAS-IV) was determined during the present study. During the present investigations, Hydropericardium Hepatitis Syndrome (HHS) showed reduced pathogenicity as compared to the isolates studied on the inception of the syndrome in 1987-1988. Pathogenicity of the virus was determined through LD₅₀ and challenge protection test. The LD₅₀ titre of the 10% viral suspension prepared from liver filtrate was found to be 10^-2.5 per ml in 26 days old broiler chicks. None of the chick showed mortality however, Hydropericardium syndrome of Angara disease was observed on postmortem of the challenged chicks and observations grossly observed in the form of lesions on liver, hydronephrosis and water around heart (yellow straw coloured). These findings proved that the injected virus suspension was biologically active.  Formalinized vaccines for HHS including Aqua Base Liver Organ (ABLO) vaccine and Oil Base Tissue Culture (OBTC) vaccine are effective for the control of the syndrome. The vaccination against HHS has positive effect on the immune response of the chicks against HHS. Due to extensive vaccination in the field there is a reduction in the virulence of the virus.

Key words: Pathogenicity, adenovirus, Angara disease, LD_50.