UBC researchers studied the case of a B.C. teen critically ill from avian flu. They were surprised

In fall 2024 a Fraser Valley teen became critically ill from the H5N1 avian flu virus. A year later a man in Louisiana died from the same virus.

Scientists began to wonder whether these cases were a sign that the avian flu virus was adapting to infecting humans, raising fears of a human H5N1 pandemic.

But new University of B.C. research sheds light on why it didn’t spread.

“It’s actually the interesting story here. It took a lot of work, but it’s that there’s no news, meaning it wasn’t the threat we thought,” said senior author Sriram Subramaniam, professor of biochemistry and molecular biology at the UBC faculty of medicine.

In a study published this week in Nature Communications, UBC researchers analyzed two mutations from the B.C. case and found they actually weakened the virus’s ability to bind to human cells.

Subramaniam’s team used a technique called cryo-electron microscopy, a high-powered microscope that allowed them to map the mutated surface protein at near-atomic detail.

Mutations can change so the research doesn’t rule out a future avian flu pandemic but Subramaniam said it was satisfying to learn the mutations weren’t cause for concern.

“The immediate concern was maybe there were these sets of mutations that would have let the virus make this jump into humans, and therefore it could continue to be a problem,” he said.

He explained the spike protein is what helps the virus to attach to the cell, and in the case of influenza, it uses sugars that normally sit on the cell surface as receptors for the virus to stick to.

“When we did the structure of the B.C. mutation, there was nothing. It was empty, and that started our entire line of discovery,” he said.

The expectation was that mutations would make the virus more likely to infect cells.

“What we found was the opposite, that it was not able to bind the sugars. Ergo, it would not have been able to enter cells.”

“Our best guess, and we’ve not proven this, is that it escaped the upper respiratory tract and made its way further in through the airways,” said Subramaniam.

He added that when patients have severe cases of flu it’s usually because of lower respiratory tract infections.

“So we think because the mutations that we saw in the teenager didn’t have the capability to bind these sugars, it kind of escaped and went further in.”

In fall and winter 2024, B.C. was in one of its worst avian influenza seasons, with millions of poultry and wild birds dying across the province.

The virus had also been found in several wild mammals, including skunks, foxes and raccoons. Human cases are rare, worldwide about 1,000 people are estimated to have had avian influenza.

Joselynn Armstrong, the Fraser Valley teen who became critically ill, survived after being on life support for weeks. Her case remains the only Canadian case of locally acquired avian influenza.

With files from Glenda Luymes

ticrawford@postmedia.com