الفهرس 
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Abstract
One hundred and sixty five (1-day old) commercial broiler chicks were obtained from local hatchery from parent flock with a history of vaccination to ND. Chicks were randomly divided into 5 groups (25 birds/group). 25 birds were kept as control non-challenged group (G1). 25 chicks per each group were challenged with 107.5 EID50 NDV VII via intraocular per bird on day 1 and on a weekly basis up to the 3rd weeks of live. On the 3rd weeks of chicken live 25 chicks were challenged intramuscular with107.5 EID50 NDV VII. Maternal antibodies equal or higher than 28.8 protect chicks fully from mortalities but not from morbidities (80% protection) and 29.95 HI maternal antibody titer to Newcastle fully protect chicks from morbidities and mortalities. Maternal antibodies equal to 28.5 or lower do not fully protect chicks from morbidities and mortalities appearance of signs, severity of signs and mortalities correlated with levels of maternal derived antibodies 100% morbidity and 80% mortality result from intra-ocular challenging NDV VII of chicks with 24.4 maternal antibody derived antibody or lower and intramuscular rout of NDV VII infection result in high morbidity and mortality rate result than intra-ocular rout. Virus shedding not detected 7 day post-challenge in birds vaccinated with either rHVT alone, rHVT with clone and twice clones vaccination. And In 3 day post-challenge same result of blocking virus shedding occur in rHVT-ND vaccinated chicks (alone or in combination with clone ) but not in birds receive clone vaccine either as single or twice times. It is clear from our data that double vaccinated with rHVT and clone give 100% protection morbidity and mortality against intra-ocular challenge with 107.5 EID50 with complete inhibit of virus shedding. although rHVT- ND vaccine alone does not give the same protective as combination of rHVT- ND and clone , yet it fully protect chicks from mortality and offered 86 .7% protection from morbidity. Live clone vaccine applied of day 1 of chicken live with high maternal immunity of 28.6 does not give good protection against NDV VII challenge (morbidity 87.5% and mortality 50%) and when twice vaccine with clone give much better protection (morbidity 37.5% and mortality 25%). The single clone but not as rHVT-ND alone as in combination with clone.