Research Shows New Flu Viruses Often Arise In Domestic Animals

[tetano]

As flu-watchers like to say, you can always count on influenza virus to surprise.

The latest revelation is that scientists have apparently been wrong about where new flu viruses come from. The dogma is that they always incubate in wild migratory birds, then get into domestic poultry, and then jump into mammals ? especially pigs and humans.

If novel flu viruses acquire the ability to transmit readily in humans ? boom! ? you've got a pandemic on your hands. And if a pandemic virus is particularly lethal, like the H5N1 bird flu virus that has made public health people anxious for the past 10 years, it could be a global catastrophe.

But evolutionary biologist Michael Worobey and his colleagues say that wild-bird scenario does not describe the true origin of the flu viruses that have troubled the world over the past 140 years.

Instead, the flu viruses circulating globally since the early 1870s are all closely related to those that infect an animal we don't associate with influenza these days: the horse.


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http://interlochenpublicradio.org/post/research-shows-new-flu-viruses-often-arise-domestic-animals

 

[tetano]

Re: Research Shows New Flu Viruses Often Arise In Domestic Animals

The original article

 

[Giuseppe]

Re: Research Shows New Flu Viruses Often Arise In Domestic Animals

[Source: Nature, full text: (LINK). Abstract, edited.]


Nature | Letter

A synchronized global sweep of the internal genes of modern avian influenza virus

Michael Worobey,<SUP>1 </SUP>Guan-Zhu Han<SUP>1 </SUP>& Andrew Rambaut<SUP>2, 3</SUP>
<SUP></SUP>
Journal name: Nature / Year published: (2014) / DOI: doi:10.1038/nature13016

Received 19 March 2013 - Accepted 10 January 2014 - Published online 16 February 2014
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Zoonotic infectious diseases such as influenza continue to pose a grave threat to human health<SUP>1</SUP>. However, the factors that mediate the emergence of RNA viruses such as influenza A virus (IAV) are still incompletely understood<SUP>2, 3</SUP>. Phylogenetic inference is crucial to reconstructing the origins and tracing the flow of IAV within and between hosts<SUP>3, 4, 5, 6, 7, 8</SUP>. Here we show that explicitly allowing IAV host lineages to have independent rates of molecular evolution is necessary for reliable phylogenetic inference of IAV and that methods that do not do so, including ?relaxed? molecular clock models<SUP>9</SUP>, can be positively misleading. A phylogenomic analysis using a host-specific local clock model recovers extremely consistent evolutionary histories across all genomic segments and demonstrates that the equine H7N7 lineage is a sister clade to strains from birds?as well as those from humans, swine and the equine H3N8 lineage?sharing an ancestor with them in the mid to late 1800s. Moreover, major western and eastern hemisphere avian influenza lineages inferred for each gene coalesce in the late 1800s. On the basis of these phylogenies and the synchrony of these key nodes, we infer that the internal genes of avian influenza virus (AIV) underwent a global selective sweep beginning in the late 1800s, a process that continued throughout the twentieth century and up to the present. The resulting western hemispheric AIV lineage subsequently contributed most of the genomic segments to the 1918 pandemic virus and, independently, the 1963 equine H3N8 panzootic lineage. This approach provides a clear resolution of evolutionary patterns and processes in IAV, including the flow of viral genes and genomes within and between host lineages.

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