T160A mutation-induced deglycosylation at site 158 in hemagglutinin is a critical determinant of the dual receptor binding properties of clade 2.3.4.4 H5NX subtype avian influenza viruses.
Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu 225009, China
Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, Jiangsu 225009, China.
Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, Jiangsu 225009, China. Electronic address: [email protected].
Most clade 2.3.4.4 H5NX subtype avian influenza viruses possess a T160A amino acid substitution in the hemagglutinin (HA) protein that has been shown to affect the receptor binding properties of a clade 2.3.4 H5N1 virus. However, the effect of this single site mutation on the HA backbone of clade 2.3.4.4 H5NX viruses remains unclear. In this study, two H5N6 field isolates possessing HA-160A with dual α-2,3 and α-2,6 receptor binding properties (Y6 virus) and HA-160T with α-2,3 receptor binding affinity (HX virus), respectively, were selected to generate HA mutants containing all of the internal genes from A/PR8/H1N1 virus for comparative investigation. We found that the Y6-P-160A and RHX-P-160A viruses each with 160A in the HA resulting in loss of glycosylation at site 158 exhibited binding to the two receptor types, whereas the RY6-P-160T and HX-P-160T viruses each with 160T in the HA displayed selective binding to α-2,3 receptors only. In addition, differences were noted in the replication of these four H5N6 recombinants in avian and mammalian cells, as well as in their pathogenicity in mice. The contribution of deglycosylation at site 158 to the acquisition of human-like receptors was further verified in H5N2, H5N5 and H5N8 reassortants. Therefore, we conclude that the lack of glycosylation at site 158 induced by the T160A mutation in HA is a critical determinant for the dual receptor binding properties of clade 2.3.4.4 H5NX viruses. This new insight may be helpful in assessing the pandemic potential of novel H5 isolates.
158Clade 2.3.4.4GlycosylationH5NXReceptorMutationAnimalsBirdsGlycosylationHemagglutinin Glycoproteins, Influenza VirusHemagglutininsInfluenza A virusInfluenza in BirdsMiceOrthomyxoviridae InfectionsPhylogenyProtein BindingReassortant Viruses
Structured evidence records
Evidence records
5 total
Genomic Evolution1 records
Genomic EvolutionExtraction confidence 0.90
Key finding
Genetic analysis of the hemagglutinin gene in clade 2.3.4.4 H5NX avian influenza viruses identified the T160A mutation as causing loss of glycosylation at site 158, enabling dual α-2,3 and α-2,6 receptor binding and indicating an evolutionary change influencing host adaptation.
Most clade 2.3.4.4 H5NX subtype avian influenza viruses possess a T160A amino acid substitution in the hemagglutinin (HA) protein... We found that the Y6-P-160A and RHX-P-160A viruses each with 160A in the HA resulting in loss of glycosylation at site 158 exhibited binding to the two receptor types... The contribution of deglycosylation at site 158 to the acquisition of human-like receptors was further verified in H5N2, H5N5 and H5N8 reassortants.
Recombinant clade 2.3.4.4 H5N6 viruses carrying the T160A mutation replicated differently in avian and mammalian cells and showed altered pathogenicity in mice, indicating expanded host range potential linked to glycosylation loss at site 158.
The T160A mutation in the HA protein of clade 2.3.4.4 H5NX avian influenza viruses causes deglycosylation at site 158, leading to dual α-2,3 and α-2,6 receptor binding and indicating adaptation toward human-like receptors.
The lack of glycosylation at site 158 induced by the T160A mutation in HA is a critical determinant for the dual receptor binding properties of clade 2.3.4.4 H5NX viruses, enabling binding to both α-2,3 and α-2,6 receptors and influencing replication and pathogenicity in avian and mammalian cells.
T160A-induced deglycosylation at HA site 158 of clade 2.3.4.4 H5NX avian influenza viruses leads to dual binding to both α-2,3 and α-2,6 sialic acid receptors, while the glycosylated 160T variants bind only α-2,3 receptors.
We found that the Y6-P-160A and RHX-P-160A viruses each with 160A in the HA resulting in loss of glycosylation at site 158 exhibited binding to the two receptor types, whereas the RY6-P-160T and HX-P-160T viruses each with 160T in the HA displayed selective binding to α-2,3 receptors only.
Receptors
α-2,3 and α-2,6 sialic acid receptors
Recombination Or Reassortment1 records
Recombination Or ReassortmentExtraction confidence 0.90
Key finding
Recombinant H5N6 and reassortant H5N2, H5N5, and H5N8 avian influenza viruses demonstrated that genetic reassortment and the T160A HA modification together influence receptor-binding and cross-species replication properties.
Two H5N6 field isolates... were selected to generate HA mutants containing all of the internal genes from A/PR8/H1N1 virus for comparative investigation. In addition, differences were noted in the replication of these four H5N6 recombinants in avian and mammalian cells... The contribution of deglycosylation at site 158... was further verified in H5N2, H5N5 and H5N8 reassortants.
