A recent study from Scripps Research has found that a single genetic alteration in the current H5N1 influenza virus circulating among U.S. dairy cows could potentially enhance its ability to infect humans. Although the current risk to humans is low, ongoing monitoring is crucial in light of this discovery.
Published in Science | Estimated reading time: 4 minutes
The highly pathogenic avian influenza (HPAI) H5N1 virus, which has been spreading in U.S. dairy farms in 2024, could pose a greater threat to humans due to a single mutation in its surface protein. Researchers at Scripps Research have identified that a minor change in the virus’s hemagglutinin protein could alter its ability to infect human cells.
The study focused on the H5N1 strain responsible for the first documented human infection with the bovine variant in Texas. The researchers highlight the potential for the virus to adapt for human-to-human transmission, raising concerns about a possible influenza pandemic.
The crucial mutation, known as Q226L (replacing glutamine with leucine at position 226), significantly changed the virus’s ability to bind to human cells. While this modification is a key step towards increased transmissibility among humans, additional mutations would likely be necessary for a pandemic to occur.
Key Findings
The research team, led by Ting-Hui Lin and colleagues, discovered that the current H5N1 virus strongly favors avian-type receptors but can switch to human-type receptors with the Q226L mutation. This finding is significant as previous studies required multiple mutations to achieve a similar effect in H5N1 strains.
By October 2024, the virus had infected at least 15 individuals globally with the 2.3.4.4b variant, including cases linked to exposure to infected cows and poultry. While current infections have been mild, historical H5N1 infections have led to more severe outcomes.
Glossary
- Hemagglutinin (HA)
- A protein on the surface of influenza viruses that facilitates cell attachment and infection
- Receptor Specificity
- The ability of a virus to recognize and bind to specific molecules on cell surfaces
- Mutation
- A genetic change that can alter an organism’s or virus’s characteristics
Test Your Knowledge
What specific mutation could enhance H5N1’s ability to infect human cells?
The Q226L mutation, replacing glutamine with leucine at position 226 in the hemagglutinin protein.
Why does the current H5N1 virus primarily affect birds rather than humans?
Due to its preference for avian-type receptors in the hemagglutinin protein, which are less common in human respiratory tracts.
How many mutations were typically required in past H5N1 strains to switch receptor preference?
Previous studies indicated that three or more mutations were usually needed to switch from avian to human receptors.
Why is this finding worrisome from a public health standpoint?
The fact that only one mutation is required significantly raises the likelihood of the virus adapting to infect humans, compared to needing multiple simultaneous mutations.
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