Molecular characterization of low pathogenic avian influenza H9N2 virus during co-circulation with newly-emerged highly pathogenic avian influenza H5N8 virus in Iran.

 Identification of molecular characteristics of low pathogenic avian influenza (LPAI) H9N2 virus provides insights into the evolution of this subtype due to the modulation of genomic characteristics in co-circulation with another subtype. The present study aimed to analyze the molecular and phylogenetic characteristics of the current LPAI H9N2 virus in characteristics of internal proteins are crucial for the adaptations of AIVs viruses to a new host. Since H9N2 is indigenous among poultry, continuous monitoring of viral genetic changes is needed for risk assessment of potential transmissibility to human population and emergence of new reassortant virus. domestic poultry during the emergence of new highly pathogenic avian influenza (HPAI) H5N8 virus in Iran. To this end, deep sequencing of LPAI H9N2 virus was performed on Illumina MiSeq sequencing platform and the complete sequences of avian influenza viruses were obtained from GISAID EpiFlu database. Phylogenetic analysis of the surface and internal gene segments showed that the H9N2 2018 virus was closely related to Pakistani H9N2 isolates. HA cleavage site motif sequence of the Iranian isolate was 317KSSR GLF323. The A/chicken/Iran/1/2018 H9N2 strain carried the amino acid substitution (Q216L), which is a mutation correlated with a shift in the affinity of the HA from avian type sialic receptors to human type. Besides surface glycoproteins, molecular. Keywords: A/H9N2; molecular characterization; A/H5N8; co-circulation; A/H5N1; Illumina MiSeq.