Adaptability of avian influenza viruses poses threat to poultry

New insights from a study of the 2016/2017 avian influenza outbreak in Eurasia show how highly pathogenic avian influenza viruses – which are likely to cause severe disease in chickens – can be transmitted from wild migrating bird populations to domestic flocks and back again.

These viruses can readily exchange genetic material with other low pathogenic viruses – which are less harmful – during migration, raising the likelihood of serious outbreaks in domestic poultry and wild birds, scientists have found.

Research led by a team including the Roslin Institute, representing the Global Consortium for H5N8 and Related Influenza Viruses, studied the genetic makeup of the 2016/2017 avian influenza virus in various birds at key stages during the influenza season.

Their study offers insights into the outbreak strains, which originated in domestic birds in Asia before spreading via wild migratory flocks to create the largest avian influenza epidemic in Europe to date.

The team interpreted genetic sequence data from virus samples collected during the outbreak together with details of where, when and in which bird species they originated.

Researchers used a computational technique, known as phylogenetic inference, to estimate when and where the virus exchanged genetic material with other viruses in wild or domestic birds.

The virus could easily exchange genetic material with other, less harmful viruses, at times and locations corresponding to bird migratory cycles, results showed. These included viruses carried by wild birds on intersecting migratory routes, and by farmed ducks in China and central Europe.

Migrating birds harbouring weaker viruses are more likely to survive their journey and potentially pass disease to domestic birds.

The research, published in Proceedings of the National Academy of Sciences, was carried out in collaboration with the Friedrich Loeffler Institut, Germany, the Erasmus University Medical Center, Netherlands, and the University of Edinburgh’s Usher Institute and Roslin Institute.

It was supported by funding from EU Horizon 2020, EPIC and BBSRC.

Article: Lycett, S. J., Pohlmann, A., Staubach, C., Caliendo, V., Woolhouse, M., Beer, M., Kuiken, T., Global Consortium for H5N8 and Related Influenza Viruses (2020). Genesis and spread of multiple reassortants during the 2016/2017 H5 avian influenza epidemic in Eurasia. Proceedings of the National Academy of Sciences of the United States of America, 202001813, online 7 August 2020, doi: 10.1073/pnas.2001813117

[SOURCE: The Roslin Institute]