Researchers Believe Bird-flu Was Not A Threat To Humans

UK Researchers are now reporting that the Bird flu may not have been as threatening to humans as was originally believed because our noses are too cold for the virus to thrive.

A re-creation of the environment of the nose done by Imperial College London shows that at 89.6 degrees Fahrenheit the avian flu viruses lose the ability to function and spread.

It is quite possible that the viruses have adapted to withstand the warmer 104 degree environment in the bowels of birds.
They say that a mutation is necessary to make the bird flu a danger to humans.

The study, published in the journal PLoS Pathogens, also found that human viruses are affected by the colder temperatures found in the nose but not to the same extent.

The researchers said that human viruses are still able to replicate and spread under those circumstances. 

Both of the viruses were able to successfully grow at normal human body temperatures of 98.6 degrees, which is the same as the environment in the lungs.

They were also able to create a mutated human flu virus by adding a certain protein from the surface of an avian influenza virus.

This virus serves as an example of how a new strain could potentially develop and cause a pandemic, but was also unsuccessful at 89.6 degrees.

Study leader Professor Wendy Barclay says this information suggests that if a new human influenza strain evolved by mixing with an avian influenza virus, it would still have to further mutate in order for it to successfully infect humans. 

“Our study gives vital clues about what kinds of changes would be needed in order for them to mutate and infect humans, potentially helping us to identify which viruses could lead to a pandemic.”

She added that further research might point to warning signs in viruses that are beginning to make the genetic changes necessary for them to cross over to humans.

“Animal viruses that spread well at low temperatures in these cultures could be more likely to cause the next pandemic than those which are restricted.”

She said swine flu that was spreading from person to person through what seemed to be upper respiratory tract infection was likely an example of a virus adapting to cope with the cooler temperatures of the nose.

“This work confirms the fact that temperature differences in the avian and human sites of influenza infection are key to virus establishment,” said Professor Ian Jones, an expert in virology at the University of Reading.

“It is certainly part of the explanation of why avian viruses, such as H5N1, fail to transmit readily to humans.”

He added that the research also revealed that the proteins on the outside of the virus were essential to its function at different temperatures.

“This helps the monitoring of avian flu as it indicates which changes to look out for.”


On The Net:

PLoS Pathogens

Imperial College London