Low pathogenic avian influenza (LPAI) H9N2 viruses have established endemic status in Egyptian poultry populations since 2012. Recently, four cases of human H9N2 virus infections in Egypt demonstrated the zoonotic potential of these viruses. Egyptian H9N2 viruses obtained from 2011 to 2014 phylogenetically grouped into three clusters (1-3) within subclade B of the G1 lineage. Antigenically, a close clustering of the Egyptian H9N2 viruses with other recent G1-B like H9N2 strains and a significant antigenic distance from viruses outside the G1-B lineage was evident. Recent Egyptian LPAIV H9N2 showed a tendency to increased binding with erythrocytes expressing α 2,6-linked sialic acid which correlated with the Q226L amino acid substitution at the receptor binding unit of the hemagglutinin (Q234L, H9 numbering). Sequence analyses of the N2 neuraminidase (NA) revealed substitutions in the NA hemadsorption site similar to the N2 of prepandemic H3N2/1968, but no distinct antigenic or functional characteristics of the H9N2 NA associated with increased zoonotic potential could be identified.
Antigenic characterizationAvian influenzaEgyptH9N2HumanNeuraminidase activityZoonosisGenetic VariationAnimalsCluster AnalysisEgyptGenotypeHemagglutinin Glycoproteins, Influenza VirusHumansInfluenza A Virus, H9N2 SubtypeInfluenza in BirdsInfluenza, HumanNeuraminidase
Structured evidence records
Evidence records
4 total
Genomic Evolution1 records
Genomic EvolutionExtraction confidence 0.90
Key finding
Phylogenetic and sequence analyses placed Egyptian H9N2 viruses into three clusters within the G1 lineage and identified amino acid substitutions in HA and NA indicative of genetic diversification and receptor-binding adaptation.
Egyptian H9N2 viruses obtained from 2011 to 2014 phylogenetically grouped into three clusters (1-3) within subclade B of the G1 lineage. Sequence analyses of the N2 neuraminidase (NA) revealed substitutions in the NA hemadsorption site similar to the N2 of prepandemic H3N2/1968.
Genes or proteins
hemagglutinin; neuraminidase
Analysis methods
phylogenetic analysis; sequence analysis
Molecular Adaptation1 records
Molecular AdaptationExtraction confidence 0.88
Key finding
The hemagglutinin Q226L (H9 numbering Q234L) substitution in Egyptian H9N2 influenza viruses was associated with increased binding to α2,6-linked sialic acid receptors, reflecting adaptation toward human-type receptor binding.
Recent Egyptian LPAIV H9N2 showed a tendency to increased binding with erythrocytes expressing α 2,6-linked sialic acid which correlated with the Q226L amino acid substitution at the receptor binding unit of the hemagglutinin (Q234L, H9 numbering).
Genes or proteins
hemagglutinin
Receptors
α2,6-linked sialic acid
Mutations
Q226L; Q234L
Mechanism types
receptor_binding; molecular_host_adaptation
Receptor Usage1 records
Receptor UsageExtraction confidence 0.85
Key finding
Egyptian H9N2 viruses exhibited stronger binding to α2,6-linked sialic acid receptors due to a Q226L substitution in hemagglutinin, indicating enhanced human-type receptor affinity.
Recent Egyptian LPAIV H9N2 showed a tendency to increased binding with erythrocytes expressing α 2,6-linked sialic acid which correlated with the Q226L amino acid substitution at the receptor binding unit of the hemagglutinin.
Method
binding assay
Receptors
α2,6-linked sialic acid
Spillover Event1 records
Spillover EventExtraction confidence 0.95
Key finding
Four cases of human infection with avian influenza H9N2 viruses occurred in Egypt, evidencing avian-to-human spillover.
