OmniVira

Genetic Characteristics and Pathogenicity of Recent G4 Eurasian Avian-like H1N1 Swine Influenza Viruses in China.

Jing Yang1 Chaoyang Chen1,2 Zhiliang Zhang1 Jiaxuan Li1 Wen Cui1,3 Yanping Jiang1,3 Xiaona Wang1,3 Lijie Tang1,3
Affiliations 3 institutions
  1. College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China.
  2. Sinovet (Jiangsu) Biopharmaceuticals Co., Ltd., Taizhou 225300, China.
  3. Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Harbin 150030, China.
PMID42797971 DOI10.3390/vetsci13090936 Year2026 Journal Veterinary sciences Vet Sci Languageeng Publication statusActive
Active Last checked 2026-09-28 03:31:06 Source: NCBI PubMed

Abstract

G4 Eurasian avian-like H1N1 (G4 EA-H1N1) swine influenza viruses continue to be detected in pigs in China and remain a concern because of their reassortant genomes and zoonotic potential. Here, six H1N1 viruses isolated from pigs with respiratory disease in six Chinese provinces during 2023-2025 were characterized. Phylogenetic analysis showed that all six isolates belonged to the G4 genotype and retained the characteristic genomic constellation, with EA-lineage HA and NA genes, pdm09-derived PB2, PB1, PA, NP, and M segments, and a triple-reassortant NS segment. Sequence analysis identified amino acid substitutions in HA antigenic and receptor-binding-associated regions and differences in predicted HA and NA glycosylation patterns. Molecular docking indicated that the HAs could accommodate both α2,3- and α2,6-linked sialic acid receptor analogs. Hemagglutination inhibition testing of 96 field swine sera showed that 62 samples (64.6%) had titers ≥ 1:40 against the representative isolate JS0602, with seroreactivity to JS0602 detected among sera from all sampled regions. JS0602 replicated efficiently in MDCK cells and caused respiratory signs, pulmonary lesions, viral antigen deposition, and viral shedding in experimentally infected pigs. These findings provide updated genetic and biological information on contemporary G4 EA-H1N1 viruses and support continued surveillance in swine populations.

Supporting text Virus Host Location
Eurasian avian-like 1 genomic surveillance 12 pathogenicity 61 phylogenetic analysis 71 swine influenza A virus 2

Evidence records

7 total
Zoonotic Surveillance
2 records · 2 evidence types
Evidence type Virus Isolation
1 records
OVE12231 Virus Isolation
Key finding

Six H1N1 viruses belonging to the G4 genotype were isolated from pigs with respiratory disease in six Chinese provinces during 2023–2025.

Virus
JS0602 Influenza A virus H1N1 G4 Eurasian avian-like H1N1
Host
pigs with respiratory disease Natural host
Location
Not specified
Supporting text

Here, six H1N1 viruses isolated from pigs with respiratory disease in six Chinese provinces during 2023-2025 were characterized.

Evidence type Serological Evidence
1 records
OVE12235 Serological Evidence
Key finding

Among 96 field swine sera, 64.6% had HI titers ≥1:40 against the G4 EA-H1N1 isolate JS0602, with seroreactivity observed across all sampled regions.

Virus
JS0602 G4 EA-H1N1
Host
field swine Natural host
Location
Not specified
Supporting text

Hemagglutination inhibition testing of 96 field swine sera showed that 62 samples (64.6%) had titers ≥ 1:40 against the representative isolate JS0602, with seroreactivity to JS0602 detected among sera from all sampled regions.

Method
Hemagglutination inhibition testing
Sample type
sera
Experimental Infection
2 records · 2 evidence types
Evidence type Pathogenicity Experiment
1 records
OVE12237 Pathogenicity Experiment
Key finding

Experimental infection of pigs with the G4 EA-H1N1 isolate JS0602 caused respiratory signs, pulmonary lesions, viral antigen deposition, and viral shedding.

Virus
JS0602 G4 EA-H1N1
Host
pig Sus scrofa Experimental system
Location
Not specified
Supporting text

JS0602 replicated efficiently in MDCK cells and caused respiratory signs, pulmonary lesions, viral antigen deposition, and viral shedding in experimentally infected pigs.

Method
experimental infection of pigs | antigen detection (viral antigen deposition) | shedding assessment (viral shedding measurement)
Experimental system
experimentally infected pigs (animal model)
Evidence type Host Range Experiment
1 records
Functional Mechanism
2 records · 2 evidence types
Evidence type Receptor Usage
1 records
OVE12234 Receptor Usage
Key finding

G4 EA-H1N1 HA shows predicted binding compatibility with both α2,3- and α2,6-linked sialic acid receptor analogs.

Virus
G4 EA-H1N1
Host
Not specified
Location
Not specified
Supporting text

G4 Eurasian avian-like H1N1 (G4 EA-H1N1) swine influenza viruses continue to be detected in pigs in China and remain a concern because of their reassortant genomes and zoonotic potential. Molecular docking indicated that the HAs could accommodate both α2,3- and α2,6-linked sialic acid receptor analogs.

Method
molecular docking
Receptors
α2,3-linked sialic acid | α2,6-linked sialic acid
Evidence type Molecular Adaptation
1 records
OVE12233 Molecular Adaptation
Key finding

G4 EA-H1N1 HA exhibits features in antigenic/receptor-binding regions and docking supports accommodation of both α2,3- and α2,6-linked sialic acid receptors, indicating dual-receptor usage potential.

Virus
G4 EA-H1N1
Host
Not specified
Location
Not specified
Supporting text

Sequence analysis identified amino acid substitutions in HA antigenic and receptor-binding-associated regions and differences in predicted HA and NA glycosylation patterns. Molecular docking indicated that the HAs could accommodate both α2,3- and α2,6-linked sialic acid receptor analogs.

Genes or proteins
HA | NA
Receptors
α2,3-linked sialic acid | α2,6-linked sialic acid
Mechanism types
receptor binding | receptor usage | host-range expansion
Genomic Evolution
1 records · 1 evidence types
Evidence type Phylogenetic Evolution
1 records
OVE12232 Phylogenetic Evolution
Key finding

Phylogenetic analysis placed six 2023–2025 swine H1N1 isolates in the G4 genotype with EA-lineage HA/NA, pdm09-derived PB2/PB1/PA/NP/M, and a triple‑reassortant NS segment.

Virus
G4 EA-H1N1 Influenza A virus H1N1
Host
pig Sus scrofa Natural host
Location
Not specified
Supporting text

Here, six H1N1 viruses isolated from pigs with respiratory disease in six Chinese provinces during 2023-2025 were characterized. Phylogenetic analysis showed that all six isolates belonged to the G4 genotype and retained the characteristic genomic constellation, with EA-lineage HA and NA genes, pdm09-derived PB2, PB1, PA, NP, and M segments, and a triple-reassortant NS segment.

Genes or proteins
HA | NA | PB2 | PB1 | PA | NP | M | NS
Analysis methods
Phylogenetic analysis | Genomic constellation analysis