الفهرس 
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Abstract
In this study the genetic evolution and the antigenic characterization of circulated H9N2 viruses in Egypt were defined.
One hundred and twenty three 123 samples were selected from the diseased birds that were collected from Damietta province and examined for different types of the circulating avian influenza, which represent the circulating Egyptian viruses from 2014 till 2018 from chicken and ducks .Screening of samples for AIV detection especially H9 using Real Time RT-PCR: revealed 23 positive cases for subtype H5 and H9 of avian influenza virus with percentage of 8 % for H5 and 10% for H9 and threshold cycle ranged for positive results from 18 to 31.61 for H9 gene and 22.6 to 30.73 for H5 gene. The positive selected samples were propagated and isolated in SPF ECE at 9-11 day old via intra/allantoic method. all the harvested allantoic fluid were submitted to slide HA to detect the presence of heamaggluting viruses in the samples.
The molecular study for the selected Egyptian avian influenza H9N2 isolates were started with extracting the RNA of the allantoic fluids of the isolates, and then they were tested by real time PCR with high positivity for H9 viruses ,H5 and negative results for other suspected hemagglutinating viruses (H7and NDV). The HA gene of the selected isolates was partially amplified by conventional PCR and then purified for nucleotide sequencing process. The genetic analysis for the sequence of HA gene revealed that, The Egyptian isolates have high identity % to each other (96-99%.