Pathfinder
Editor, Senior Moderator
Q&A: Richard Webby of the WHO on the new deadly flu strain
By Christie Nicholson | October 19, 2013, 8:00 PM PDT
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This particular virus had features that concerned us. There are specific mutations in its genome that we associate with an increased ability to grow in mammals. And our laboratory studies found an elevated ability of this virus, as compared to most other avian viruses, to transmit.
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I think it is more infectious than H5. It?s probably more infectious than H9 which is another virus we sporadically see in humans.
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The H-type is the most variable part of that virus. That is why we call them H1, H3, H5 and H7 because they are very different. We are not expected to have immunity to the H5 or we are not expected to have much immunity to the H7. That is one reason they cause disease.
It is a little bit of a mystery as to why this H7N9 causes such severe disease but it does.
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We group flu viruses into pathogenic types. Highly pathogenic or low pathogenic. Some viruses of the H5N7 type fall into a very virulent form. And we know how they do this. They accumulate additional amino acids in their H protein. The H5N1 is one of these highly virulent forms. If it has that extra amino acid, it kills chickens. And it?s associated with severe disease in humans.
Even though H7 can also do that, this particular virus does not have that extra bit.
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I think it is inevitable that there will be another pandemic.
But if you look at the pandemics we?ve seen they have all been from viruses of the H1, H2 and H3 type. In 1918 with H1, 1957 with H2, 1968 with H3 and in 2009 with H1 again. So in terms of H1, H2 and H3 types I think it is a matter of when it will happen again rather than if it will happen again.
There is still a question with these other more classical avian types like the H5 and H7. I personally believe that they probably have the ability to become a human pathogen.
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Full text:
http://www.smartplanet.com/blog/pur...of-the-who-on-the-new-deadly-flu-strain/10850
By Christie Nicholson | October 19, 2013, 8:00 PM PDT
...
This particular virus had features that concerned us. There are specific mutations in its genome that we associate with an increased ability to grow in mammals. And our laboratory studies found an elevated ability of this virus, as compared to most other avian viruses, to transmit.
...
I think it is more infectious than H5. It?s probably more infectious than H9 which is another virus we sporadically see in humans.
...
The H-type is the most variable part of that virus. That is why we call them H1, H3, H5 and H7 because they are very different. We are not expected to have immunity to the H5 or we are not expected to have much immunity to the H7. That is one reason they cause disease.
It is a little bit of a mystery as to why this H7N9 causes such severe disease but it does.
...
We group flu viruses into pathogenic types. Highly pathogenic or low pathogenic. Some viruses of the H5N7 type fall into a very virulent form. And we know how they do this. They accumulate additional amino acids in their H protein. The H5N1 is one of these highly virulent forms. If it has that extra amino acid, it kills chickens. And it?s associated with severe disease in humans.
Even though H7 can also do that, this particular virus does not have that extra bit.
...
I think it is inevitable that there will be another pandemic.
But if you look at the pandemics we?ve seen they have all been from viruses of the H1, H2 and H3 type. In 1918 with H1, 1957 with H2, 1968 with H3 and in 2009 with H1 again. So in terms of H1, H2 and H3 types I think it is a matter of when it will happen again rather than if it will happen again.
There is still a question with these other more classical avian types like the H5 and H7. I personally believe that they probably have the ability to become a human pathogen.
...
Full text:
http://www.smartplanet.com/blog/pur...of-the-who-on-the-new-deadly-flu-strain/10850