Multi-species study aids understanding of avian influenza

They examined the response to 6 species: 2 that are susceptible to bird flu (chicken and turkey) but also duck and crow, which tolerate and spread disease, and goose and pigeon, which are known to be highly resistant.

The team from The Roslin Institute, Edinburgh, sought to pinpoint biological differences that affect the outcomes of infection. The results showed:

• In chickens and turkeys, exposure was found to lead to very high amounts of the virus, which accumulated in several organs, including the brain.
• Pigeons had low amounts of the virus in their bodies and showed a low immune response following exposure. This suggests they have an inherent ability to prevent viruses from entering cells or spreading.
• Genetic differences may explain a variation in how ducks and crows, which typically show similar responses to infection, differ in their reaction to some types of severe flu.

The study, which is one of the first to compare responses to the brain, suggests that this impact on the organ may be the cause of sickness and death from flu in chickens and turkeys.

On the other hand, pigeons may be protected by having high levels of what is known as interferon-stimulated genes, which are involved in the immune response to infection.

A speedy innate immune response to infection

The results also highlighted the benefits of a speedy innate immune response to infection, as delayed reactions tend to lead to worse outcomes.

Commenting on the study, which was published in Frontiers in Cellular and Infection Microbiology, Dr Katrina Morris from the Roslin Institute said: “Understanding the biological processes triggered by avian flu, and the factors that influence resistance, is important in the effort to limit the risk of bird flu in commercial poultry.

“Our findings show that early interaction involving the immune system is key. They also highlight the importance of interplay between the birds’ nervous and immune systems in response to infectious disease and flag several genes that may be influential in how infection plays out.”