HA N193D substitution in the HPAI H5N1 virus alters receptor binding affinity and enhances virulence in mammalian hosts.

Seung-Gyu Jang1 Young-Il Kim2 Mark Anthony B Casel1,3 Jeong Ho Choi1 Ju Ryeon Gil1 Rare Rollon1 Eun-Ha Kim2 Se-Mi Kim2 Ho Young Ji2 Dong Bin Park2 Jungwon Hwang4 Jae-Woo Ahn2 Myung Hee Kim4 Min-Suk Song1,3 Young Ki Choi1,2,3
Affiliations 4 institutions
  1. College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju, Republic of Korea.
  2. Center for Study of Emerging and Re-emerging Viruses, Korea Virus Research Institute, Institute for Basic Science (IBS), Daejeon, Republic of Korea.
  3. Zoonotic Infectious Diseases Research Center, Chungbuk National University, Cheongju, Republic of Korea.
  4. Microbiome Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.
Active Last checked 2026-10-02 03:30:39 Source: NCBI PubMed

Abstract

During the 2021/2022 winter season, we isolated highly pathogenic avian influenza (HPAI) H5N1 viruses harbouring an amino acid substitution from Asparagine(N) to Aspartic acid (D) at residue 193 of the hemagglutinin (HA) receptor binding domain (RBD) from migratory birds in South Korea. Herein, we investigated the characteristics of the N193D HA-RBD substitution in the A/CommonTeal/Korea/W811/2021[CT/W811] virus by using recombinant viruses engineered via reverse genetics (RG). A receptor affinity assay revealed that the N193D HA-RBD substitution in CT/W811 increases α2,6 sialic acid receptor binding affinity. The rCT/W811-HA193N virus caused rapid lethality with high virus titres in chickens compared with the rCT/W811-HA193D virus, while the rCT/W811-HA193D virus exhibited enhanced virulence in mammalian hosts with multiple tissue tropism. Surprisingly, a ferret-to-ferret transmission assay revealed that rCT/W811-HA193D virus replicates well in the respiratory tract, at a rate about 10 times higher than that of rCT/W811-HA193N, and all rCT/W811-HA193D direct contact ferrets were seroconverted at 10 days post-contact. Further, competition transmission assay of the two viruses revealed that rCT/W811-HA193D has enhanced growth kinetics compared with the rCT/W811-HA193N, eventually becoming the dominant strain in nasal turbinates. Further, rCT/W811-HA193D exhibits high infectivity in primary human bronchial epithelial (HBE) cells, suggesting the potential for human infection. Taken together, the HA-193D containing HPAI H5N1 virus from migratory birds showed enhanced virulence in mammalian hosts, but not in avian hosts, with multi-organ replication and ferret-to-ferret transmission. Thus, this suggests that HA-193D change increases the probability of HPAI H5N1 infection and transmission in humans.

Supporting text Virus Host Location
Clade 2.3.4.4 3 HPAI H5N8 virus 1 Influenza infections 1 pathogenecity 1 reassortant 13 South Korea 5 Influenza A virus 191 Influenza A Virus, H5N1 Subtype 308 Influenza in Birds 352 Animals 1981 Chickens 149 Ferrets 79 Hemagglutinins 24 Humans 1455 Virulence 110

Evidence records

5 total
Zoonotic Surveillance
1 records · 1 evidence types
Evidence type
1 records
OVE7692
Key finding

Highly pathogenic avian influenza H5N1 viruses carrying the HA N193D substitution were isolated from migratory birds in South Korea during the 2021/2022 winter season.

Virus
Host
Location
Not specified
Supporting text

During the 2021/2022 winter season, we isolated highly pathogenic avian influenza (HPAI) H5N1 viruses harbouring an amino acid substitution from Asparagine(N) to Aspartic acid (D) at residue 193 of the hemagglutinin (HA) receptor binding domain (RBD) from migratory birds in South Korea.

Experimental Infection
2 records · 2 evidence types
Evidence type
1 records
OVE7694
Key finding

The recombinant rCT/W811-HA193N H5N1 virus caused rapid lethality with high virus titres in chickens under controlled infection conditions.

Virus
Host
Location
Not specified
Supporting text

The rCT/W811-HA193N virus caused rapid lethality with high virus titres in chickens compared with the rCT/W811-HA193D virus.

Method
in vivo infection comparison | viral titre measurement in infected chickens
Experimental system
chicken infection model
Evidence type
1 records
OVE7696
Key finding

The rCT/W811-HA193D virus transmitted between ferrets in a direct-contact transmission assay and induced seroconversion in all contact ferrets.

Virus
Host
Location
Not specified
Supporting text

a ferret-to-ferret transmission assay revealed that rCT/W811-HA193D virus replicates well in the respiratory tract, at a rate about 10 times higher than that of rCT/W811-HA193N, and all rCT/W811-HA193D direct contact ferrets were seroconverted at 10 days post-contact.

Method
ferret-to-ferret transmission assay | direct contact transmission model | seroconversion assessment
Experimental system
ferret-to-ferret direct contact transmission assay
Functional Mechanism
2 records · 2 evidence types
Evidence type
1 records
OVE7693
Key finding

The N193D substitution in the HA receptor binding domain of A/CommonTeal/Korea/W811/2021 (H5N1) increases viral affinity for the α2,6-linked sialic acid receptor.

Virus
Host
Location
Not specified
Supporting text

A receptor affinity assay revealed that the N193D HA-RBD substitution in CT/W811 increases α2,6 sialic acid receptor binding affinity.

Method
receptor affinity assay
Receptors
α2,6 sialic acid receptor
Host factors
hemagglutinin (HA) receptor binding domain
Evidence type
1 records
OVE7699
Key finding

The HA N193D substitution in HPAI H5N1 increases α2,6 sialic acid receptor binding affinity and enhances mammalian adaptation and transmission potential.

Virus
Host
Not specified
Location
Not specified
Supporting text

A receptor affinity assay revealed that the N193D HA-RBD substitution in CT/W811 increases α2,6 sialic acid receptor binding affinity. ... the rCT/W811-HA193D virus exhibited enhanced virulence in mammalian hosts with multiple tissue tropism. Surprisingly, a ferret-to-ferret transmission assay revealed that rCT/W811-HA193D virus replicates well in the respiratory tract ... Taken together, the HA-193D containing HPAI H5N1 virus from migratory birds showed enhanced virulence in mammalian hosts, but not in avian hosts, with multi-organ replication and ferret-to-ferret transmission.

Genes or proteins
hemagglutinin (HA) | HA receptor binding domain (RBD)
Receptors
α2,6 sialic acid receptor
Host factors
primary human bronchial epithelial (HBE) cells
Mutations
N193D | HA-193D
Mechanism types
receptor binding | host-range expansion | tissue tropism | virulence adaptation | transmission fitness | replication adaptation