OmniVira

Characterization of two chicken origin highly pathogenic H7N9 viruses isolated in northern China.

Jinyuan Gu1 Yayao Yan1 Zixiong Zeng1 Wenli Wang1 Ruyi Gao2,3,4 Jiao Hu2,3,4 Shunlin Hu2,3,4 Xiaoquan Wang2,3,4 Min Gu2,3,5 Xiufan Liu2,3,6
Affiliations 6 institutions
  1. Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, China.
  2. Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
  3. Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
  4. Jiangsu Key Laboratory of Zoonoses, Yangzhou University, Yangzhou, China.
  5. Jiangsu Key Laboratory of Zoonoses, Yangzhou University, Yangzhou, China. Electronic address: [email protected].
  6. Jiangsu Key Laboratory of Zoonoses, Yangzhou University, Yangzhou, China. Electronic address: [email protected].
PMID35316713 DOI10.1016/j.vetmic.2022.109394 Year2022 Journal Veterinary microbiology Vet Microbiol Languageeng Statusppublish

Abstract

Since the national vaccination program was implemented with the H5/H7 bivalent vaccine in poultry in September 2017, the prevalence of H7N9 avian influenza viruses (AIVs) has been controlled effectively in China. However, highly pathogenic H7N9 viruses still exist, causing sporadic outbreaks especially in some regions of northern China. During our routine surveillance in poultry in 2020, we isolated two strains of H7N9 subtype AIV from breeder layer farms in northern China. We found that these two chicken-origin H7N9 isolates were both highly pathogenic (HP) with a four-amino-acid (KRTA) insertion and an I326V mutation (H3 numbering) in the cleavage site of HA to make the motif PEVPKRKRTAR↓GLF. Molecular markers associated with antigenic drift and enhanced pathogenicity in mammals and interspecies transmission were detected in both isolates. Remarkably, both strains gained the F102V and N157D mutations in their HA genes, which have never been reported before. Solid-phase direct binding assay showed that these two isolates both had dual-receptor binding characteristics, while thermal and acid stability assays indicated that they were relatively stable in high-temperature or acidic conditions. In addition, the animal experiments demonstrated that both strains were highly pathogenic to chickens but low pathogenic to mice. These results suggested that the evolution of H7N9 subtype AIV is still continuing, and they pose a potential threat to poultry and public health. Thus, attention should be paid to the importance of continual surveillance of the H7N9 AIVs.

Supporting text Virus Host Location
Acid stability 1 Dual-receptor characteristics 1 H7N9 subtype avian influenza virus 1 Highly pathogenic 3 Thermal stability 1 Influenza A Virus, H7N9 Subtype 87 Influenza in Birds 341 Animals 1948 Chickens 146 China 229 Hemagglutinin Glycoproteins, Influenza Virus 180 Mammals 92 Mice 253 Phylogeny 805 Poultry 112

Evidence records

3 total
Zoonotic Surveillance
1 records · 1 evidence types
Evidence type Virus Isolation
1 records
OVE5787 Virus Isolation
Key finding

Two strains of H7N9 subtype AIV were isolated from breeder layer farms in northern China during poultry surveillance in 2020.

Virus
Influenza A virus H7N9
Host
birds Aves Natural host
Location
Not specified
Supporting text

During our routine surveillance in poultry in 2020, we isolated two strains of H7N9 subtype AIV from breeder layer farms in northern China.

Experimental Infection
2 records · 1 evidence types
Evidence type Pathogenicity Experiment
2 records
OVE5791 Pathogenicity Experiment
Key finding

Both H7N9 strains were highly pathogenic to chickens in animal experiments.

Virus
Influenza A virus H7N9
Host
chicken Gallus gallus Experimental system
Location
Not specified
Supporting text

In addition, the animal experiments demonstrated that both strains were highly pathogenic to chickens but low pathogenic to mice.

Method
animal experiments | controlled infection observation
Experimental system
animal infection experiment
OVE5792 Pathogenicity Experiment
Key finding

Both H7N9 strains were low pathogenic to mice in animal experiments.

Virus
Influenza A virus H7N9
Host
house mouse Mus musculus Experimental system
Location
Not specified
Supporting text

In addition, the animal experiments demonstrated that both strains were highly pathogenic to chickens but low pathogenic to mice.

Method
animal experiments | controlled infection observation
Experimental system
animal infection experiment