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Editor, Senior Moderator
Health | Sat Apr 25, 2015 7:06pm EDT Related: HEALTH
New avian flu viruses send U.S. scientists scrambling
CHICAGO | BY JULIE STEENHUYSEN
(Reuters) - ...
...
The U.S. Department of Agriculture is still seeing the original H5N8 virus, but it has also identified two strains of mixed-origin viruses, both of them highly pathogenic. One is the deadly H5N2 virus. The other is an entirely new H5N1 virus that has so far been found in only a handful of the recent cases.
Because much is still unknown about these new viruses, the USDA and the CDC are conducting detailed analyses that include sequencing the viruses' genomes. A key question they hope to answer is whether the viruses might mutate and become human viruses.
"This is something we need to avoid: it is something that could happen and which we have to look for," said Dr. Jurgen Richt, an expert in avian influenza at Kansas State University.
Richt said scientists also need to find out whether the viruses are mutating when they come from a wild host into domesticated poultry.
...
Donis said the CDC is currently conducting studies in ferrets, which are used as surrogate models for humans, to see how the viruses behave in mammals and whether they can spread easily to animals in nearby cages.
One good sign already is that the H5N2 virus does not appear to be able to replicate readily at lower temperatures, which is required for transmission from person to person.
...
The CDC has already studied a lab-developed version of the avian hemagglutinin, the "H" portion of the viruses, to see if it contains receptors that could easily attach to human cells. In these experiments, the "H" has bound strictly to avian receptors, and not human receptors, another good sign that the virus may not be easily transmissible in people.
"So far, what we see is a typical avian virus that is not expected to be transmissible in ferrets," ...
...
The mere fact that an H5N1 avian influenza virus has arrived in North America, however, represents a significant evolution.
Before 1996, none of the highly pathogenic viruses survived very long in nature. H5N1 viruses had largely been confined to Southeast Asia.
"They always burned out and they were never transmitted long distances repeatedly by wild birds," Donis said.
...
http://www.reuters.com/article/2015/04/25/us-health-birdflu-virus-insight-idUSKBN0NG0ZJ20150425
New avian flu viruses send U.S. scientists scrambling
CHICAGO | BY JULIE STEENHUYSEN
(Reuters) - ...
...
The U.S. Department of Agriculture is still seeing the original H5N8 virus, but it has also identified two strains of mixed-origin viruses, both of them highly pathogenic. One is the deadly H5N2 virus. The other is an entirely new H5N1 virus that has so far been found in only a handful of the recent cases.
Because much is still unknown about these new viruses, the USDA and the CDC are conducting detailed analyses that include sequencing the viruses' genomes. A key question they hope to answer is whether the viruses might mutate and become human viruses.
"This is something we need to avoid: it is something that could happen and which we have to look for," said Dr. Jurgen Richt, an expert in avian influenza at Kansas State University.
Richt said scientists also need to find out whether the viruses are mutating when they come from a wild host into domesticated poultry.
...
Donis said the CDC is currently conducting studies in ferrets, which are used as surrogate models for humans, to see how the viruses behave in mammals and whether they can spread easily to animals in nearby cages.
One good sign already is that the H5N2 virus does not appear to be able to replicate readily at lower temperatures, which is required for transmission from person to person.
...
The CDC has already studied a lab-developed version of the avian hemagglutinin, the "H" portion of the viruses, to see if it contains receptors that could easily attach to human cells. In these experiments, the "H" has bound strictly to avian receptors, and not human receptors, another good sign that the virus may not be easily transmissible in people.
"So far, what we see is a typical avian virus that is not expected to be transmissible in ferrets," ...
...
The mere fact that an H5N1 avian influenza virus has arrived in North America, however, represents a significant evolution.
Before 1996, none of the highly pathogenic viruses survived very long in nature. H5N1 viruses had largely been confined to Southeast Asia.
"They always burned out and they were never transmitted long distances repeatedly by wild birds," Donis said.
...
http://www.reuters.com/article/2015/04/25/us-health-birdflu-virus-insight-idUSKBN0NG0ZJ20150425