Virus survival and fitness when multiple genotypes and subtypes of influenza A viruses exist and circulate in swine

Virology. 2019 Jun;532:30-38. doi: 10.1016/j.virol.2019.03.016. Epub 2019 Apr 9.

Abstract

We performed swine influenza virus (SIV) surveillance in Midwest USA and isolated 100 SIVs including endemic and reassortant H1 and H3 viruses with 2009 pandemic H1N1 genes. To determine virus evolution when different genotypes and subtypes of influenza A viruses circulating in the same swine herd, a virus survival experiment was conducted in pigs mimicking field situations. Five different SIVs were used to infect five pigs individually, then two groups of sentinel pigs were introduced to investigate virus transmission. Results showed that each virus replicated efficiently in lungs of each infected pig, but only reassortant H3N2 and H1N2v viruses transmitted to the primary contact pigs. Interestingly, the parental H1N2v was the majority of virus detected in the second group of sentinel pigs. These data indicate that the H1N2v seems to be more viable in swine herds than other SIV genotypes, and reassortment can enhance viral fitness and transmission.

Keywords: H1N2v; Pigs; Surveillance; Swine influenza virus; Virus competition and survival.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Epidemiological Monitoring
  • Genetic Fitness
  • Genotype
  • Influenza A Virus, H1N1 Subtype / classification
  • Influenza A Virus, H1N1 Subtype / genetics*
  • Influenza A Virus, H1N1 Subtype / pathogenicity
  • Influenza A Virus, H1N2 Subtype / classification
  • Influenza A Virus, H1N2 Subtype / genetics*
  • Influenza A Virus, H1N2 Subtype / pathogenicity
  • Influenza A Virus, H3N2 Subtype / classification
  • Influenza A Virus, H3N2 Subtype / genetics*
  • Influenza A Virus, H3N2 Subtype / pathogenicity
  • Midwestern United States / epidemiology
  • Orthomyxoviridae Infections / epidemiology
  • Orthomyxoviridae Infections / transmission
  • Orthomyxoviridae Infections / veterinary*
  • Orthomyxoviridae Infections / virology
  • Phylogeny
  • Reassortant Viruses / classification
  • Reassortant Viruses / genetics*
  • Reassortant Viruses / pathogenicity
  • Swine
  • Swine Diseases / epidemiology*
  • Swine Diseases / transmission
  • Swine Diseases / virology
  • Virus Replication