الفهرس 
2.1-Historical backgroundOnly 14 pages are availabe for public view
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Abstract
In this study, characterization of some Newcastle disease virus (NDV) isolates from different localities and different years in Egypt carried out and eleven NDV field samples were detected by Real time polymerase chain reaction (rRT-PCR).11 out of 53 samples were positive for NDV. The Pathogenicity of each isolate was determined by mean death time (MDT) 9 isolates were found of virulent type with MDT less than 60 hrs and two isolates showed MDT more than 90 hrs.11 isolates were positive HA and HI tests using NDV Lasota antisera. Partial fusion gene sequence of 9 isolates which were of virulent type revealed (112-R/GRQKR*F-117) cleavage site sequence. The two isolates which were found to have (112-R/GRQGR*L-117) cleavage site sequence. Phylogenetic analysis of the sequenced part of fusion protein and comparison of them with other reference strains from GeneBank revealed that eight isolates are close to genotype VI and three isolates are close to genotype II.