الفهرس 
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Abstract
Newcastle disease virus (NDV) is a highly contagious disease of poultry and it is listed as list A by OIE as a notifiable disease virus due to its cause severe outbreaks and morbidity in the susceptible host so it is considered as greater exhaustion to the economy of the world. Velogenic NDV causes a great affection on the economy as high mortalities, a great reduction in feed conversion rate, and egg production. This study aims to determine genotypes and Pathotyping of NDV in Egypt in three provenance (Ismailia, Suez, and Zagazig) in the period 2019 to 2020 through making isolation of one hundred samples in Embryonated chicken eggs (ECE), followed by hemagglutination (HA) and hemagglutination inhibition test (HI). Moreover, the
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conventional PCR (RT-PCR) was done for positive samples followed by gel electrophoresis, then gene sequencing of F gene has been made and compared them with circulating strains and vaccinal strains which present in Gene bank, then the pathotypes and the genotypes of isolates in this study. The Pathotyping and genotyping of these collected isolates were done through sequencing of full and partial F gene. Results indicated that the 4 NDV isolates showed a characteristic cleavage site motif (112RRQKRF117) for the velogenic strains of NDV. Phylogenetic analysis of the F gene clustered these isolates within Genotype VII.1.1. Keywords: Newcastle disease virus, Fusion gene, Sequencing, and Phylogenetic Analysis.