Characterization of Avian Influenza H9N2 Virus in Broiler Chicken Backyard Flocks in Three Egyptian Governorates during Late Autumn 2023

Sabry, Ahmed; Ibrahim, Mahmoud; Zahra, Abo Elnasr A.; AboElkhair, Mohammed

doi:10.21608/jcvr.2025.462642

Characterization of Avian Influenza H9N2 Virus in Broiler Chicken Backyard Flocks in Three Egyptian Governorates during Late Autumn 2023

Document Type : Original Article

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10.21608/jcvr.2025.462642

Abstract

Background: Low pathogenic avian influenza viruses (LPAIV) H9N2 considered as one of the most prevalent infectious agents in Egyptian poultry farms since its first introduction in 2011 and one of the most important potential pandemic threats.
Methods: Thirty samples were collected from backyard broiler chicken flocks from three Egyptian governorates (Menoufia, Gharbia and Buhayrah) during late autumn of 2023. All of these flocks were not vaccinated against LPAIV H9N2. All collected samples were screened by Real time reverse transcriptase polymerase chain reaction (rRT-PCR) for detection of Avian influenza viruses (H9, H5 and H7), Newcastle disease virus (NDV) and Infectious bronchitis virus (IBV) then virus isolation of H9 positive samples followed by molecular and phylogenetic analysis of two isolates from Menoufia and Gharbia governorates through full Haemagglutinin (HA) gene sequencing.
Results: The results of rRT-PCR showed that the prevalence of LPAIV (H9N2) was 20 % while the prevalence of NDV and IBV was 63 % and 56% respectively. Molecular and phylogenetic analysis reveals that our isolates were clustered with the recent Egyptian strains from 2020 till 2023. our isolates harbor the molecular markers 191H, 234L and 198A at the HA gene which indicate their potential zoonotic significance. Additionally, the potential glycosylation sites in our isolates are similar to all compared Egyptian strains since 2011. Analysis of the amino acid (aa) identity % shows the highest identity % between the two isolates of the current study (98.8), however the identity percent with the Egyptian isolate in 2011 was about 95%.
Conclusions: This study highlights the continued prevalence and evolution of H9N2 LPAIV in poultry flocks in Egypt with co-circulation of other respiratory viruses (NDV and IBV). Moreover, the role of vaccination besides biosecurity can’t be neglected as effective control measures.

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