A new pandemic brewing? Alarming mutation in H5N1 virus sparks concerns

Can avian influenza be the next pandemic after Coronavirus? Scientists do not rule out this possibility and feel that a single mutation can make H5N1 virus much more infectious for humans. A potential mutation in the H5N1 avian influenza virus is likely to increase its ability to infect humans, a genetic change that could lead to the next pandemic, as per experts.

A study published in Science and funded by NIH highlights a mutation in the virus’s protein, which could enable it to better bind to human cell receptors. While the risk of human-to-human transmission remains low, scientists are closely monitoring the virus.

It has found that a single alteration in a protein on the surface of the highly pathogenic avian influenza (HPAI) H5N1 virus, currently present in US dairy cows, may greatly increase its potential for human-to-human transmission.

While people exposed to infected wild birds, poultry, dairy cows, and other mammals have been infected with the virus, till now the bovine (cow) H5N1 virus is not capable of human-to-human transmission.

Researchers have been studying H5N1 to track natural genetic mutations and find out their potential impact on transmissibility.

Which genetic change can increase risk of a pandemic

Influenza viruses use a surface protein called hemagglutinin (HA) to attach to cells by binding with sugar (glycan) receptors. Avian influenza viruses like H5N1 is not able to infect humans as their upper respiratory cells do not have the specific receptors that are found in birds. However, this may change, fear the scientists.

Experts from scientific community feel that the virus can develop the capability to evolve and recognize human-type receptors in the upper airways, which means they would be able to infect humans and spread between people.

Scientists at Scripps Research studied the H5N1 strain from the first U.S. human infection with the bovine strain 2.3.4.4b (A/Texas/37/2024) to investigate how mutations in the virus's hemagglutinin (HA) protein affected its ability to bind to avian versus human cell receptors.

To understand this, the researchers introduced several mutations into the viral HA protein that had been observed to occur naturally in the past and discovered that one mutation, called Q226L, improved the ability of the protein to attach to receptors usually found on human cells, especially when an additional mutation was present. Also, the researchers introduced the genetic mutations only into the HA surface protein and did not create or conduct experiments with a whole, infectious virus.

While the Q226L mutation alone does not point towards an imminent pandemic, the findings highlight that there is a need for ongoing monitoring and outbreak control efforts.

Early this year, the first human-infecting bovine H5N1 case involving close contact with infected dairy herds was reported in Texas. This marked the outbreak of HPAI H5N1 virus in dairy cattle in the US. A multistate outbreak of HPAI A(H5N1) bird flu in dairy cows was first reported on March 25, 2024. This is the first time that these bird flu viruses had been found in cows, as per CDC.

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