The results of experiments for studying the properties of live virus that causing duck hepatitis virus (DHV) disease in duckling and trial to prepare a laboratory batch of the vaccine are summarized in the following:
the embryo was 100% The higher percentage ofthe pathogenicity to
when the virus was inoculated via allantoic cavity (A/C) and 9-%, 75% for chorio-allantoic membrane (CAM) and yolk sac (Y/C) respectively. The best route of inoculation of the virus was on CAM which gave the highest titer (1086/ml), while the titer was 1083/mi and 107-8/ml for A/C and yolk sаc respectively. The best hour for harvestation of DHV was 72 hours post inoculation (Pl) since the titer was 10%/m! for A/C and 10°/ml for CAM. The best site for virus multiplication is the whole embryo tissues as the titer obtained was (10'/ml), while it was 100-6/ml, 100ml in both CAM and ammnio-allantoic fluid (AAF) respectively. The results of thermostability revealed that the loss in virus titer was O at +10°V while it was 0.8, 0.8, 1.7 and 5.8 log, when held for 1 hour at 25°C, 37°C, 40°C and 56°C respectively. The results of keeping quality of the freez-dried live (DHV) vaccine showed that the average loss of virus titer was 2 log after 9 months storage at the refrigerator temperature (+4°C). After 7 months storage at room temperture there was 6.1 log drop in the virus titer than the original virus, while when the virus was kept at the deep freezer (-20°C) for more than 1 year no significance loss in the virus titer was detected.