Two genetic mutations that alarmed scientists after a British Columbia teenager became critically ill with H5N1 bird flu in November 2024 appear to have weakened the virus's ability to attach to human cells, not strengthened it. Researchers at the University of British Columbia reported the finding on September 28 in the peer-reviewed journal Nature Communications.

The result runs against the early worry that the Canadian case, the country's first human infection reported in the province, signaled a virus adapting to people. According to the UBC Faculty of Medicine, the mutated surface protein bound poorly to both human-type and bird-type cell receptors in laboratory tests. The patient recovered.

The finding is reassuring about these two specific mutations, but it does not lower overall vigilance. For readers, it matters because these viruses continue to circulate in wild birds, poultry, and U.S. dairy cattle, and scientists rely on this kind of laboratory testing to decide which genetic changes deserve real concern.

Receptor Binding in Plain Terms

Influenza viruses begin an infection by using a surface protein called hemagglutinin to latch onto sugar molecules, called sialic acid receptors, on the outside of cells. Bird-adapted viruses generally prefer the type common in bird airways, while human seasonal flu viruses prefer the type that dominates the human upper respiratory tract. A switch toward human-type receptors is one of the classic warning signs scientists watch for.

The B.C. virus carried two unusual changes in exactly that binding region, reported as E190D and Q226H. A similar mutation later appeared in samples from a Louisiana patient who died of the disease, UBC said, which heightened concern that the virus might be moving toward human adaptation. Sequencing showed a mixed population of viruses in the B.C. patient, with each mutation present in roughly a third of sequence reads, so the variants of interest were a substantial minority rather than the dominant form.

Inside the Laboratory Tests

The UBC team, led by Sriram Subramaniam, a professor of biochemistry and molecular biology, used cryogenic electron microscopy to map the mutated protein at near-atomic detail. They then measured how well it gripped human-type and bird-type receptors using glycan microarrays and laboratory binding assays. Both forms of attachment were severely reduced, the opposite of the shift toward human-type receptors that would signal adaptation to people.

"To our surprise, the mutations did the opposite of what many expected," Subramaniam said in the university's announcement.

That raised a puzzle: how did the virus infect someone at all? Testing in human lung cells showed the mutated protein could still trigger fusion with the cell membrane, the step that lets the virus deliver its genetic material, though at roughly a third the level of a well-studied earlier H5N1 strain. First author John Ni, a graduate student in the Subramaniam lab, suggested that many weak interactions between viral proteins and cell receptors may collectively provide enough attachment for the virus to function.

Limits of the Evidence and a Competing Reading

This is laboratory research on viral proteins and cells, based on mutations found in one patient. It shows what these two changes do to receptor binding under controlled conditions. It does not measure how easily the virus spreads between people, and it does not predict the behavior of other mutations. The authors also note the virus may use receptors their arrays did not test.

An independent team offered a different interpretation of the same mutations in a preprint posted to bioRxiv in July, which has not yet been peer-reviewed. That group, working with engineered viruses and pseudoviruses, also found no gain in human-type receptor use, but reported that the mutations helped the virus escape human airway mucus and replicate better in the presence of the antivirals oseltamivir and zanamivir. In other words, weaker binding is not automatically the same as a weaker threat, and the question remains open. A separate peer-reviewed study in npj Virus similarly found that the E190D substitution reduces receptor binding and viral fitness.

Subramaniam cautioned that other changes in the same region of the protein could have very different effects. The UBC work was supported through Canada's Immuno-Engineering and Biomanufacturing Hub.

Surveillance from Wild Birds to Farm Workers

The case shows how the monitoring chain is supposed to work. Scientists at the B.C. Centre for Disease Control sequenced the patient's virus and shared the data, which let the UBC team test what the mutations actually did. Genetic sequencing flags changes quickly, but laboratory work is needed to tell a meaningful warning sign from one that only looks alarming on paper.

For U.S. readers, the most exposed people remain those in close contact with infected animals, including poultry and dairy workers, backyard flock owners, and hunters who handle wild birds. The Centers for Disease Control and Prevention says the current public health risk from H5 bird flu is low, listing 71 human cases reported in the United States since February 2024 on a page last updated in March.

Practical steps have not changed. Avoid touching sick or dead wild birds, keep pets away from carcasses, report unusual die-offs to state wildlife agencies, and use recommended protective gear when working with poultry or livestock. Anyone who develops eye redness or flu-like symptoms after animal exposure should contact a health care provider and mention the exposure. This study does not change official guidance.

Researchers will keep testing mutations as new cases and animal outbreaks are sequenced, and the competing preprint interpretation may be tested further in peer review. Nature World News will follow new findings as surveillance data are released.

The two mutations from the B.C. case weakened the virus's binding to both human-type and bird-type receptors in UBC's laboratory tests, easing one specific worry. Other scientists read the same changes differently, and the researchers warn that different mutations could matter more, so surveillance of wild birds, farms, and people remains essential.

What Readers Want to Know

What did the UBC study find?

It found that two mutations from a severe Canadian H5N1 case severely reduced the virus's binding to both human-type and bird-type cell receptors in laboratory tests.

Does this mean bird flu is less dangerous?

Not in general. The finding applies to these two mutations only. The researchers warn that other changes in the same region could have very different effects, and an independent preprint suggests weaker binding may help the virus in other ways.

Who was the patient?

A British Columbia teenager who became critically ill in November 2024 with respiratory failure. The patient recovered.

How could the virus infect someone if binding was weaker?

Tests showed the mutated protein could still fuse with human lung cells, though far less efficiently. The researchers suggest many weak interactions may add up to enough attachment.

Is bird flu a risk to the general public?

The CDC says the current public health risk is low. People who work closely with poultry, dairy cattle, or wild birds face higher exposure.

What should people do to reduce exposure?

Avoid sick or dead wild birds, keep pets away from carcasses, report die-offs to wildlife agencies, and seek medical advice if symptoms follow an animal exposure.