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Antigenic and genetic characterization of H9N2 swine influenza viruses in China.

Yan L Cong1 Juan Pu1 Qin F Liu1 Shuai Wang1 Guo Z Zhang1 Xing L Zhang1 Wei X Fan2 Earl G Brown3 Jin H Liu1
Affiliations 3 institutions
  1. Laboratory of Infectious Diseases, College of Veterinary Medicine, State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100094, PR China.
  2. China Animal Health and Epidemiology Center, Qingdao 266032, PR China.
  3. Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, ON, Canada.
PMID 17554038 2007 J Gen Virol eng ppublish
PubMed DOI Browse context

Article

Publication summary

As pigs are susceptible to infection with both avian and human influenza A viruses, they have been proposed to be an intermediate host for the generation of pandemic virus through reassortment. Antigenic and genetic characterization was performed for five swine H9N2 influenza viruses isolated from diseased pigs from different farms. The haemagglutinin (HA) antigenicity of swine H9N2 viruses was different from that of chicken H9N2 viruses prevalent in northern China. Genetic analysis revealed that all five isolates had an RLSR motif at the cleavage site of HA, which was different from those of A/duck/Hong Kong/Y280/97 (Dk/HK/Y280/97)-like viruses established in chickens in China. Phylogenetic analyses indicated that the five swine H9N2 viruses formed novel HA and neuraminidase sublineages that were related closely to those of earlier chicken H9 viruses and were also consistent with the extent of the observed antigenic variation. The six internal genes of the isolates possessed H5N1-like sequences, indicating that they were reassortants of H9 and H5 viruses. The present results indicate that avian to porcine interspecies transmission of H9N2 viruses might have resulted in the generation of viruses with novel antigenic and genetic characteristics; therefore, surveillance of swine influenza should be given a high priority.

Amino Acid Sequence Animals Antigens, Viral Chickens China Hemagglutinin Glycoproteins, Influenza Virus Humans Influenza A Virus, H9N2 Subtype Influenza in Birds Influenza, Human Molecular Sequence Data Orthomyxoviridae Infections Phylogeny Reassortant Viruses Sequence Homology, Amino Acid Sus scrofa Swine Swine Diseases

Structured evidence records

Evidence records

4 total
Cross Species Transmission 1 records
Cross Species Transmission Extraction confidence 0.95
Key finding

Avian-to-swine cross-species transmission of H9N2 influenza viruses occurred in China, producing novel antigenic and genetic variants in pigs.

Virus
IAV H9N2
Location
China China
Supporting text

The present results indicate that avian to porcine interspecies transmission of H9N2 viruses might have resulted in the generation of viruses with novel antigenic and genetic characteristics.

Method
antigenic characterization; genetic analysis; phylogenetic analysis
Study design
phylogenetic analysis
Transmission direction
animal-to-animal
Geographic raw
China
Country inferred
China
Genomic Evolution 1 records
Genomic Evolution Extraction confidence 0.90
Key finding

Phylogenetic and genetic analyses showed that swine H9N2 viruses in China formed novel HA and NA sublineages related to chicken H9 viruses and had internal H5N1-like genes, demonstrating reassortment and genomic evolution following avian-to-swine transmission.

Virus
IAV H9N2
Host
Sus scrofa
Location
Not specified
Supporting text

Phylogenetic analyses indicated that the five swine H9N2 viruses formed novel HA and neuraminidase sublineages that were related closely to those of earlier chicken H9 viruses and were also consistent with the extent of the observed antigenic variation. The six internal genes of the isolates possessed H5N1-like sequences, indicating that they were reassortants of H9 and H5 viruses.

Genes or proteins
HA; NA; six internal genes
Analysis methods
phylogenetic analysis; genetic analysis
Recombination Or Reassortment 1 records
Recombination Or Reassortment Extraction confidence 0.95
Key finding

Swine H9N2 influenza viruses in China were reassortants between H9 and H5 viruses, carrying internal genes from H5N1-like viruses.

Host
Not specified
Location
Not specified
Supporting text

The six internal genes of the isolates possessed H5N1-like sequences, indicating that they were reassortants of H9 and H5 viruses.

Event type
reassortment
Genes or segments
internal genes
Zoonotic Surveillance 1 records
Zoonotic Surveillance Extraction confidence 0.75
Key finding

Five H9N2 influenza viruses were isolated from diseased pigs in different farms in China and characterized antigenically and genetically as part of swine influenza surveillance.

Virus
IAV H9N2
Host
Sus scrofa
Location
China China
Supporting text

Antigenic and genetic characterization was performed for five swine H9N2 influenza viruses isolated from diseased pigs from different farms.

Method
antigenic characterization; genetic characterization
Geographic raw
China
Country inferred
China