الفهرس 
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Abstract
Human infection caused by Avian Influenza viruses (AIVs) H5N1 and H9N2 in Egypt raise the concern that these viruses have the potential to cause an influenza pandemic especially with detection of new reasserted viruses. Since the first isolation of H9N2 AIV in May 2011, continuous monitoring of this subtype in poultry population has occurred. Here, we have studied the epidemiological situation of H9N2 virus during 2015-2016 in chickens. The total positive cases were 835 cases (4.0%), 388 cases in 2015 (3.9%) and 447 cases in 2016 (4.3%). The H9N2 viruses were detected in 766 commercial flocks (4.6%) and 69 cases from house hold chickens (1.8%) in 25 different governorates. In this study, reassortment events have been detected in two viruses isolated from samples of a commercial chicken flock in Menofya governorate(A/chicken/Egypt/374V/2016) and a quail sample collected from live bird market (LBM) in Ismailia governorate (A/quail/Egypt/1253V/2016). Phylogenetic and sequencing analyses indicated that the novel reassortant H9N2 viruses acquired four genome segments from the classic Egyptian H9N2 viruses (HA, NA, NP and M) and four segments from other non-Egyptian viruses (PB2, PB1, PA and NS). Many genetic changes have been demonstrated in quail virus such as detection of new glycosylation sites at positions 206 and 306 in HA and NA genes, respectively. Genetic analysis revealed identification of a substitution V27I in M2 protein which associated with amantadine resistance and nine amino acid substitutions at the antigenic sites of HA protein in comparison with the original H9N2 virus isolated from quail in 2011. This novel reassortment H9N2 virus showed the same amino acid substitution characters that influence infection among poultry and increase tendency for human infection. This work identified continuous H9N2 virus evolution in Egypt with complicated genetic reassortment with other viruses in the environment.