There's more than one bird flu, experts warn/Ozone layer: the sequel

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There's more than one bird flu, experts warn

 

16:13 03 May 2006 NewScientist.com news service Shaoni Bhattacharya, Singapore

http://www.newscientist.com/article/dn9101-theres-more-than-one-bird-flu-experts-warn.html

 

 

 

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Asia Medial Forum: Preparing for Pandemic Influenza Bird flu special report, New Scientist

 

 

 

The deadly H5N1 bird flu which is currently sweeping across the globe is not the only potential candidate virus for the next human flu pandemic strain, experts have warned.

At an international meeting of top scientists and policymakers in Singapore on Wednesday, several other avian flu viruses were highlighted. Hiroshi Kida, at Hokkaido University in Sapporo, Japan, told New Scientist he was concerned that only the H5N1 virus was being considered in terms of producing a human vaccine. “There are other possibilities,” he says.

There are about three human flu pandemics every century, and most scientists agree that the world is overdue for the next one. This would happen if an avian influenza strain either mutated or swapped genes with other flu strains to become both highly pathogenic and easily transmissible between humans.

It is "perfectly possible" that the next pandemic strain could derive from something other than the H5N1 strain, agrees Malik Peiris, a microbiologist at the University of Hong Kong, China.

Flu virus strains are named after two surface proteins which are important for its binding – haemagglutinin, the H component, and neuraminidase, the N component. There are 15 known variations on the H receptor and 9 on the N receptor for influenza A.

Nasty outcome

Peiris notes that the 1957 and 1968 human pandemic flu strains did not come from a highly pathogenic bird flu virus like H5N1. He says that a milder virus like H9N2, which is present all over the world, could be the next pandemic strain.

Other pandemic candidates include the H7N7 strain, which came to attention in the UK last week, when a single human case was diagnosed. It also killed a vet in an outbreak in The Netherlands in 2003, after jumping to at least 89 people from poultry. In the human case it had undergone a mutation which made it more dangerous.

But Peiris adds that when H9N2 infects humans it currently causes a mild disease, whereas there could be a “very nasty outcome” if H5N1 were to become pandemic.

“So all the attention focused on it is very, very valid,” he says. The latest outbreak, which has spread from south Asia, via Qinghai Lake in China, to Europe and Africa, has caused 205 human cases and 113 deaths (see New Scientist's bird flu special report).

Frozen faeces

But there are dozens of strains of bird flu in circulation in the wild, says Kida. In a four year study, which is still ongoing, he and colleagues isolated bird flu subtypes from over 10,000 samples of faecal matter from wild ducks in Alaska, Siberia, Mongolia, China and Japan. The frozen samples were collected from lakes during the winter. The researchers found 49 different bird flu strains.

And when they experimentally infected pigs with these bird flu strains, many of them underwent genetic reassortment. Pigs are thought to act as a “mixing vessel” for flu and other diseases, where new combinations of genes from different strains can come together. The team has also created 76 other flu subtypes in the lab by genetic reassortment.

They have 123 combinations of H and N subtypes stocked as potential vaccine strain candidates. Kida believes these may be “invaluable” as potential vaccine strains and also for diagnostics. “Any subtype could get into humans,” he says.

Overall, scientists have isolated every bird flu subtype – H1 to H15 and N1 to N9 –from ducks which remain symptom-free, says Kida.

Probably stopping HAARP slicing it to shreds and US and Russia dropping nukes at the poles helps too. N

Ozone layer: the sequel

 

18:00 03 May 2006 From New Scientist Print Edition. Subscribe and get 4 free issues.

http://www.newscientist.com/article/dn9103-ozone-layer-the-sequel.html

 

 

 

 

 

THE ozone layer will make a comeback, but not in the form we know and love.

That's the idea that has emerged from a new analysis of the recovery of the ozone layer, which was damaged by the large-scale release into the atmosphere of chlorofluorocarbons (CFCs) from aerosols and refrigerants.

While the layer may recover by around 2050, its composition will probably be subtly different to its form before 1980, when CFCs were banned under the Montreal protocol. Its new form might affect how much it can protect us from harmful ultraviolet radiation from the sun.

"The big news is that the Montreal protocol seems to be working," says Betsy Weatherhead of the University of Colorado in Boulder, whose analysis with Bech Andersen of the Danish Meteorological Institute in Copenhagen appears in Nature (vol 441, p 39). The precise make-up of the revitalised ozone layer, especially the vertical distribution of ozone, will depend on three variables: global warming, patterns of air circulation and concentrations of non-CFC gases such as nitrous oxide, which also damages ozone