New Bird Flu Seen Having Some Markers of Airborne Killer

[Pathfinder]

New Bird Flu Seen Having Some Markers of Airborne Killer

<CITE class=byline>By Simeon Bennett - Apr 5, 2013 11:39 AM CT</CITE>


The new bird influenza that?s killed six people in eastern China has some of the genetic hallmarks of an easily transmissible virus, according to the scientist who showed how H5N1 avian flu could become airborne.

The H7N9 strain, which is a new virus formed as a result of two others merging their genetic material, has features of viruses that are known to jump easily from birds to mammals, and a mutation that may help it attach to cells in the respiratory tract, said Ron Fouchier, a professor of molecular virology at Erasmus Medical Center in the Netherlands, in a telephone interview yesterday.

?That?s certainly not good news,? said Fouchier, who reviewed a gene sequencing of H7N9 published by Chinese health authorities. ?This virus really doesn?t look like a bird virus anymore; it looks like a mammalian virus.?

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http://www.bloomberg.com/news/2013-04-05/new-bird-flu-seen-having-some-markers-of-airborne-killer.html

[Emily]

Re: New Bird Flu Seen Having Some Markers of Airborne Killer

?This virus is certainly of more concern than the vast majority of bird flu viruses,? Fouchier said. ?Most bird flu viruses that we know do not have these mutations.?

Whether those mutations alone are enough to make the virus easily transmissible isn?t clear, and should be ?high on the research agenda,? Fouchier said. Still, there?s no evidence yet that the virus is more likely to become more dangerous than H5N1, he said.

?Even if we see relatively high numbers of human cases, it doesn?t mean a pandemic is imminent,? he said. ?H5N1 has circulated for 16 years and not become mammal-to-mammal transmissible.?

So he is just encouraging research. The article says that those 2 mutations are the same as 2 of the 5 that evolved in his ferret study, but were those 2 mutations even involved in heightened transmission, or were the other 3 solely responsible? The virus wasn't precisely engineered and tested in subunits the way you test computer code.

Maybe someone who has been following Fouchier's work closely knows if more is known about the function of those 2 specific mutations.

[NS1]

Re: New Bird Flu Seen Having Some Markers of Airborne Killer

Detailed analyses at China - H7N9 Human Isolates on Deposit at GISAID

[AlaskaDenise]

Re: New Bird Flu Seen Having Some Markers of Airborne Killer

So he is just encouraging research. The article says that those 2 mutations are the same as 2 of the 5 that evolved in his ferret study, but were those 2 mutations even involved in heightened transmission, or were the other 3 solely responsible? The virus wasn't precisely engineered and tested in subunits the way you test computer code.

Maybe someone who has been following Fouchier's work closely knows if more is known about the function of those 2 specific mutations.

A free article about his paper, noting those mutations is here.

(snipped from article)

"Fouchier’s team began by adding three mutations to an H5N1 strain isolated from Indonesia in 2005. Two of these — Q222L and G224S — changed the HA gene such that its protein preferentially sticks to human-type receptors over those found in bird cells. The third — E627K — changed the PB2 gene, which is involved in copying the virus’ genetic material, so that the virus was able to replicate more easily in the cooler environment of mammalian cells.

The team allowed this mutant virus to evolve naturally by passing it from one ferret to the next, injecting it into the animals' noses and collecting samples daily for four days. After ten rounds, the virus could spread between ferrets housed in separate cages.

These airborne strains spread less effectively than the 2009 H1N1 virus, and are sensitive to current antiviral treatments and potential vaccines. They are lethal if delivered directly to the ferrets’ airways in high doses, but not if the animals catch the infections naturally through the air.

Fouchier’s airborne viruses carried a diverse array of mutations, with just five mutations shared by them all, including the original three that Fouchier had inserted and two more in the HA gene: T156A, which affects receptor binding, and H103Y, which stabilizes the protein. The five mutations might be enough for H5N1 to spread between ferrets, but it may take nine or even more. “Until the changes are introduced in combinations into H5N1 virus, we won’t know the answer,” says Racaniello.....

In a related paper published in Science3, Derek Smith from the University of Cambridge, UK, and his colleagues has shown that wild H5N1 viruses already have many of the mutations that Fouchier and Kawaoka identified. Some of the viruses are two to four nucleotide substitutions away from the complete sets. However, whether those mutations would allow different strains of H5N1 to spread between ferrets, let alone humans, remains unclear.

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