Comparative pathogenicity of liver homogenate and cell culture propagated agents of hydropericardium syndrome was studied in broiler birds. In Experiment I, 25-day-old while in experiment II, broiler birds at different ages were inoculated through different routes. In Experiment I, liver homogenate caused 64% mortality through intramuscular route and 33.33% mortality through oral route. The cell culture propagated HPS virus caused 60 and 13.33% mortality in broiler birds through intramuscular and oral routes, respectively. In Experiment II, none of the day-old-chicks died when challenged with liver homogenate and cell culture propagated HPS virus through S/C and oral route. The liver homogenate and cell culture propagated HPS virus caused higher mortality in different age groups of broiler birds through s/c route compared to oral route. The values of hemoglobin (Hb) and packed cell volume (PCV) showed highly significant (P<0.05) reduction indicating anemia. The values of Hb and PCV of the broiler birds inoculated with infectious liver homogenate were significantly lower as compared to birds inoculated with cell culture propagated HPS virus. The results indicated that the liver homogenate is more pathogenic than cell culture propagated HPS virus. These changes may be due to adoptability of the original FAdVs (fowl adenovirus) after continued passages in the culture of chicken embryo liver cells. Importance of this study in vaccine production is also discussed.

Key words: Cell culture propagated; HPS virus; Hydro pericardium; syndrome (HPS); Infectious liver homogenate