Molecular and antigenic traits on hemagglutinin gene of avian influenza H9N2 viruses: Evidence of a new escape mutant in Egypt adapted in quails. (June 2017)

• Record Type: Journal Article
• Authors: Adel, Amany; Arafa, Abdelsatar; Hussein, Hussein A.; El-Sanousi, Ahmed A.
• Is Part Of: Research in veterinary science. Volume 112(2017)
• Page Start: 132
• Page End: 140
• Publication Date: 2017-06
• Subjects: HPAI Highly pathogenic avian influenza -- LPAI Low pathogenic avian influenza -- HA Hemagglutinin -- RBS Receptor binding sites -- PCS Proteolydtic cleavage site -- HI Hemagglutination inhibition assay -- RT-PCR Reverse transcriptase polymerase chain reaction -- WHO World Health Organization -- dN Non-synonymous substitution rate -- dS Synonymous substitution rate -- qu Quail -- ck Chicken; LPAI H9N2 -- HA gene -- Genetic characterization -- Antigenic cartography -- Glycosylation sites -- Antigenic sites -- Quails -- Egypt; Veterinary medicine -- Periodicals; Veterinary Medicine -- Periodicals; Médecine vétérinaire -- Périodiques; Médecine vétérinaire -- Recherche -- Périodiques; Diergeneeskunde; 636.089
• DOI: 10.1016/j.rvsc.2017.02.003
• Languages: English
• ISSNs: 0034-5288

Abstract

Abstract: The LPAI viruses of H9N2 subtype became widely distributed in Middle Eastern countries, causing great economic losses in poultry industry especially when complicated with other pathogens. The H9N2 viruses in Egypt have a wide spread nature since its first occurrence in 2011. In this study, we collected cloacal and tracheal samples from 19 flocks for detection and propagation of H9N2 virus using real-time RT-PCR and egg inoculation. We studied the molecular evolution of the Hemagglutinin gene of H9N2 viruses by full HA gene sequencing, then the antigenic characterization was implemented using the cross HI assay and analyzed using 3D Bioinformatics cartography software. The phylogenetic analysis of the HA gene of Egyptian H9N2 viruses clearly points out the presence of only one group (Egy/G1) of originally introduced viruses in 2011 related to the G1 lineage within group B, with the presence of multiple minor clusters includes viruses from 2011 to 2015. However, a new variant (Egy/G1var) cluster was detected in quails since 2012. Genetically, Egy/G1var viruses characterized by presence of 20 amino acid substitutions within and adjacent to the antigenic sites in comparison to other Egyptian viruses. In addition, two glycosylation sites at amino acid residues 127 and 189 were determined in close to the receptor binding and antigenic sites. The antigenic analysis based on 3D antigenic mapping showed that the Egy/G1var cluster was clearly distinct from the original Egy/G1 viruses. In conclusion, Egy/G1var is shown to be a new escape mutant variant cluster with an adaptive evolution in quails. Highlights: The Egyptian H9N2 LPAI viruses showed continuous genetic and antigenic evolution. New genetic and antigenic variant Egyptian LPAI H9N2 viruses were evolved and adapted in quails. The Egyptian variant viruses have at least 20 aa substitutions within and nearby the antigenic sites and RBS. The variant viruses acquired 2 new additional glycosylation sites around the antigenic sites and RBS.