Bird flu is just FOUR small mutations away from causing human pandemic, experts say
Bird flu is just four mutations away from being able to jump to humans and cause a pandemic, experts warn.
The virus has had ample opportunity to spread in recent years as it ravages the world’s population of birds and mammals.
Each time it begins to replicate in a new host, it earns another chance to mutate and potentially acquire one of these deadly traits.
Some of the mutations it could acquire that pose a risk to humans include the ability to survive in the air and optimize itself to infect human cells.
Experts highlight four key traits that bird flu can pick up on through mutation that could lead it to cause a pandemic event in humans. Two of the mutations should occur on the hemagglutinin, the outer parts of the virus responsible for binding to human cells. These mutations allow it to travel through the air and evade the body’s natural defenses. Other changes include tuning itself to better connect to human viruses rather than birds, and optimizing itself to hit cell proteins
Dr. Mathilde Richard, a virologist at the Erasmus Medical Center in the Netherlands, told Science magazineThis is the threat that will keep knocking at our door until it does, I assume, cause a pandemic.
“Because there’s no turning back.”
Before the virus can harm people, it will have to get to them first.
Currently, a person can become infected with bird flu after viral particles enter their body through the mouth, nose or eyes.
Usually this happens when someone touches an infected surface and then wipes their face.
However, these cases are rare, with only about 1,000 cases ever discovered in humans.
In a groundbreaking 2012 studyDutch researchers engineered the H5N1 bird flu to spread through the air between ferrets.
This type of research falls under the controversial “gain-of-function” label and is restricted in most of the world.
But through their studies, the team identified changes in the virus’ bindings that allow it to travel through the air and attach to human cells, its RNA code and allow it to infect more efficiently and escape natural barriers.
Viral pathogens, such as COVID-19, the flu, and respiratory syncytial virus, are transmitted most effectively through the air.
But bird flu has trouble spreading through aerosol particles.
Like other pathogens, avian flu attaches to a host’s cell through a component called hemagglutinin. These are small proteins on the outer layer of the virus.
When the virus infects an animal’s cell, the hemagglutinin fuses with fluid in the cell called the vesicle.
It merges with it due to the high acidity of the liquid. This allows the virus to melt into the cell and infect the membrane – an inner layer of cell protection.
Once inside the membrane, the virus can damage the cell with little resistance, completely infect it and then transmit itself further when it begins to replicate.
Because water and other surfaces have a relatively balanced pH, the virus can survive on surfaces for long periods of time.
But it’s a different story when it travels through the air after a person sneezes or coughs from particles.
Carbon dioxide in the air causes it to become slightly acidic. As a result, the hemagglutinin will begin to melt and will not reach a new host.
Scientists say if bird flu’s hemagglutinin mutates to more closely resemble that of Covid or flu, it could travel through the air.
Once the virus reaches the host, it must then infect it.
The second mutation optimizes the flu to bind to a human cell.
Birds fall into the ‘aves’ class within the animal kingdom, while humans are considered mammals.
This means they have a different biological makeup, enough that the virus is tailored for the animals that have problems with humans.
The avian flu has mutated to optimize itself to infect birds and, as a result, struggles to find non-avian hosts. The virus was first discovered in ducks in Europe and Asia, but it’s unclear where they picked it up.
But this could change with simple mutations of the hemagglutinin. A more optimized hemagglutinin would convert more exposures into infections, leading to a strong growth in the number of cases.
Changes in amino acids called the G228S and Q226L will be needed for this optimization to occur, scientists say after reviewing data from previous outbreaks.
When these amino acids undergo this mutation, they are better adapted to bind to carbohydrates in human cells.
These mutations were detected in previous human outbreaks of the virus.
This includes the H3N2 outbreak in 1968, which originated in America and eventually killed about 1 million people worldwide.
The outbreak of the ‘Asian flu’ in 1957 was responsible for 1.1 million deaths worldwide.
It was later determined to be caused by the H2N2 strain of bird flu, which also had these mutations.
Both strains of the virus have since disappeared from the human population, but their outbreaks show that these dangerous mutations are possible.
The woman is believed to have contracted the virus at a wet market where she spent some time before falling ill after samples taken from the market tested positive for influenza A(H3)
The woman, from Guangdong province, fell ill for the first time on February 22. She was hospitalized on March 3 with severe pneumonia and died on March 16.
The hemagglutinin isn’t the only part of the virus that should change.
The third mutation, which scientists say is the most important evolution a strain of bird flu would have to undergo to pose a threat to humans, is in its RNA.
All influenza viruses consist of single-stranded RNA as opposed to double-stranded DNA.
RNA is made up of four basic chemicals: cytosine, guanine, adenine and uracil. In DNA, thymine is present instead of uracil.
Any combination of three chemicals within the chain of RNA forms an amino acid.
These acids are the building blocks of proteins and their combination forms a large number of properties.
Unlike a cell, viruses do not have both DNA and RNA present. Most infectious diseases get their properties from their RNA makeup.
Each trio of these chemicals on an RNA chain forms a chemical responsible for proteins that help with bodily functions.
If the cytosine in some of these chains mutates to adenine instead, it will change the output of some strains from a chemical called glutamine to one known as lysine.
Scientists have called this the E627K mutation. When glutamate is replaced by lysine, the virus can infect a person’s protein cells more than a bird’s cells.
With these three mutations, the virus can likely pose a threat to humans.
But with a fourth amendment, it could bypass humans’ last defenses and trigger a deadly pandemic.
The myxovirus resistance gene A (MxA) is a protein in human cells built to destroy RNA viruses such as the avian flu.
When viral RNA is detected in the cell, the protein is activated. In most cases, it can break the binding of the pathogen and prevent infection.
When not, it signals to the immune system that there is an invader and activates a flood of white blood cells to fight the virus.
The MxA is more sensitive in humans than in other mammals, making it more difficult for the avian flu to cause an outbreak in us than in foxes, sea lions and others who have suffered from the infection in the past two years.
While Dr. Richard says the virus will inevitably reach the point where all four mutations have occurred and can affect humans, the time it takes to do so varies greatly.
Due to the randomness of genetic mutation and the very specific changes required by the virus, it can take decades for any of the changes to be made.
For now, avian flu remains a threat that people perceive but are not really concerned about.
However, human cases occasionally crop up. Officials reported that a 56-year-old woman in southeastern China died in March from the H3N8 strain of the virus.
However, the strain she suffered from is ill-tailored for humans. Only three cases of the H3N8 strain in humans have even been reported.
The strain that poses the most threat to humans is the H5N1 virus.
That strain has been recorded about 870 times since it was first discovered in 1959, killing about half of the patients.
It has ravaged the world’s wild bird population for the past two years, causing widespread infections among humans.
Unlike other strains of bird flu, it has been shown to be able to spread from human to human.
Human-to-human transmission was confirmed during an outbreak in Hong Kong in 1997 that trapped 18 people.