Is there a connection between bird flu and microRNA, the tiny bits of RNA which have different tasks in regulating genes and producing the body's building blocks?
"MicroRNA is quite stable, and interesting for us who research wildlife. It may tell us something about how animals react to various stress factors in the environment," said Veerle Jaspers, an NTNU professor who is head of a project that is examining this issue.
Researchers have checked microRNA in blood samples from ruddy turnstones (Arenaria interpres) from Australia.
Ruddy turnstones fly over long distances, and probably play an important role in the spread of bird flu. This virus is widespread in wading birds and rarely causes disease, but can mutate into a highly pathogenic form that is a threat to both wild birds and the poultry industry. So it is useful to know as much as possible about them.
But to understand why this matters, it's important to know a little more about what microRNA is.
MicroRNA is not just useless junk
Just over 30 years ago, most scientists believed that microRNAs were useless fragments that moved around in our cells and bloodstream without doing anything important.
But microRNAs have a far more important role than previously understood.
"Victor Ambros and Gary Ruvkun received this year's Nobel Prize in Physiology or Medicine for the discovery of microRNAs and the role they play in gene regulation," said Anne-Fleur Brand, a PhD research fellow at NTNU's Department of Biology.
In short, microRNAs help cells control the types and amounts of proteins they make.
What microRNAs actually do
DNA is the large genetic material in our cells. It is organized into chromosomes and genes. DNA contains recipes that determine how we look and how our bodies function. Based on these recipes, the body produces various proteins that are the body's building blocks.
The recipes from DNA are carried by messengers called messenger RNA or simply mRNA. Does this sound familiar? Several of the COVID-19 vaccines are based on mRNA. We have known about these messengers since around 1960.
What scientists didn't know about until around 1990 were microRNAs, which are even smaller. And they didn't realize that microRNAs were important until a decade later. MicroRNAs can attach to mRNA so that it doesn't send too many messages to cells to make proteins.
You could say that microRNAs help the cell fine-tune protein production, making sure it doesn't make too much or the wrong kind at the wrong time.
The ruddy turnstone's blood tests
But back to the ruddy turnstone, the small bird that may play a big role in spreading bird flu. The researchers took blood samples from the birds that correspond to about a tenth of a teaspoon from each. But this was enough to find out a lot.
"We found 163 different forms of microRNA in the ruddy turnstones. Two of these are new and unique to birds," said Brand.
The researchers checked which variants of microRNA they could find in both healthy birds and birds that were infected with a less pathogenic variant of bird flu called low pathogenic avian influenza.
"We did this to see if we could find out more about how the birds react to the infection," she said.
And they found something that could be useful. Different birds react differently to being infected with bird flu.
"We found differences in the amount of specific microRNAs in the infected birds. It seems to be related to both sex and age," Brand said.
These findings could help develop a new tool for investigating how bird flu affects wild birds.
Reference: Brand, Anne-Fleur; Waugh, Courtney Alice; Fernandes, Jorge Manuel de Oliveira; Klaassen, Marcel; Wille, Michelle; Jaspers, Veerle Leontina B. (2025) Circulating miRNAome of avian influenza-infected ruddy turnstones (Arenaria interpres). Journal of Avian Biology
