H5N1 twist tested
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One mutation could turn H5N1 from livestock nuisance to a potential human pandemic.
A study conducted from the US finds that a single genetic mutation in the H5N1 influenza virus, which is currently affecting livestock in the country, could significantly enhance its ability to infect humans.
Researchers Identified this mutation during lab-based experiments and published their findings in the journal Science.
The H5N1 virus, known for its high pathogenicity, initially emerged in birds and has since demonstrated an ability to infect mammals, including humans.
Although the virus has not shown evidence of human-to-human transmission, its adaptability has caused concern among experts monitoring potential pandemic threats.
The study focused on a bovine strain of the virus that has spread widely among dairy cattle in the United States, impacting 282 herds across 14 states by 2024.
The researchers engineered mutations in the virus's genetic makeup to examine its potential to target human receptors.
They found that a single alteration, replacing glutamine with leucine at position 226 of the virus’s hemagglutinin (HA) protein, enabled the virus to bind to human-type receptors. This change marks a significant increase in the virus's affinity for infecting human cells.
Further experiments revealed that additional mutations, such as Asn224Lys, amplified this effect, making the virus's binding strength comparable to pandemic strains like the 2009 H1N1 virus.
However, researchers emphasised that these mutations have not been observed in nature and remain confined to controlled laboratory settings.
The H5N1 strain, specifically clade 2.3.4.4b, has caused sporadic human infections with symptoms ranging from mild respiratory issues to severe illness.
Historical cases have shown mortality rates as high as 30 per cent, though this figure may overestimate the risk by excluding milder, unreported cases.
Researchers also cautioned that the combination of seasonal flu and H5N1 could lead to genetic reassortment, creating hybrid strains with greater potential for human transmission.
