WHO Refutes top Virus Hunter-Osterhaus

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   Monday, Feb 13, 2006     

Science can't predict how many mutations H5N1 needs to spark 

human pandemic 

(CP) - The World Health Organization will attempt Tuesday to dial back 

concern over how close the H5N1 avian flu virus is to becoming a strain 

that can spread easily from person to person.

The WHO is expected to issue an update clarifying that science currently 

cannot predict how many mutations the worrisome H5N1 virus would 

need to accumulate to morph into a virus that would be expected to 

infect hundreds of millions of people around the globe.

"There's no way of knowing," Michael Perdue, an avian influenza expert 

with the WHO's global influenza program, said from Geneva. "There's no 

way to make that prediction."

The statement will be an attempt to address recent widely reported 

comments made by the UN's flu czar, Dr. David Nabarro.

Nabarro, who is on secondment to the UN from the WHO, told a reporter 

from the Portuguese weekly newspaper Expresso that H5N1 is two 

mutations away from becoming easily transmissible person to person. 

The comment was widely repeated in news reports around the world.

Reached Monday at Munich Airport, Nabarro explained he was echoing a 

theory he'd heard from Dr. Ab Osterhaus, the head virologist at Erasmus 

University in Rotterdam and a central player in the community of 

scientists tracking this virus.

Osterhaus was slightly less definitive, but repeated the 

belief that "a couple" of key mutations might make the virus more 

efficient at jumping from birds to people, and then between them in 

limited fashion.

Once that limited human-to-human spread started, he suggested, the 

virus might reasonably be expected to undergo additional changes that 

would allow it to flourish in its new host. It's thought that efficient 

human-to-human transmission of the virus would trigger a flu pandemic, 

the first since the Hong Kong flu of 1968.

Still, Osterhaus admitted his theory is an educated guess at this point.

"It would be a fair statement that it would not need many mutations for 

the virus to do that in principle. But we don't know that, actually. But it 

could well be," he said.

His comments underscore the fact that despite decades of study, 

scientists are not clear what changes an avian influenza virus needs to 

undergo to fully adapt to humans.

"The science is not there yet," said Adolfo Garcia-Sastre, a microbiologist 

who researches flu at Mt. Sinai School of Medicine in New York.

Studies could be done that would chart a sort of roadmap for adaptation, 

he suggested, but researchers would first need to find an animal that 

could act as a surrogate for human infection. While it's believed ferrets 

could be that model, testing would be needed to validate that.

Then viruses would have to be manipulated in order to try to determine 

what role each of a flu virus's eight genes play in transmissibility.

"It's not quick," Garcia-Sastre said, noting this work would have to be 

done in high biocontainment laboratories.

He wasn't willing to make an on-the-record prediction of how near or far 

H5N1 is from becoming a virus that easily infects people, though he 

privately named a figure that is significantly higher than Osterhaus's 

guess.

"But it is complete speculation. So don't quote me," Garcia-Sastre said. 

� The Canadian Press, 2006

 http://www.mytelus.com/news/article.do?pageID=cp_health_home &articleID=2170203

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Guests Members Profile Send Private Message Find Members Posts Add to Buddy List Guest Group	Post Options Post Reply Quote Guests Thanks(0) Quote Reply Topic: WHO Refutes top Virus Hunter-Osterhaus Posted: February 14 2006 at 8:40am
	Monday, Feb 13, 2006 Science can't predict how many mutations H5N1 needs to spark human pandemic (CP) - The World Health Organization will attempt Tuesday to dial back concern over how close the H5N1 avian flu virus is to becoming a strain that can spread easily from person to person. The WHO is expected to issue an update clarifying that science currently cannot predict how many mutations the worrisome H5N1 virus would need to accumulate to morph into a virus that would be expected to infect hundreds of millions of people around the globe. "There's no way of knowing," Michael Perdue, an avian influenza expert with the WHO's global influenza program, said from Geneva. "There's no way to make that prediction." The statement will be an attempt to address recent widely reported comments made by the UN's flu czar, Dr. David Nabarro. Nabarro, who is on secondment to the UN from the WHO, told a reporter from the Portuguese weekly newspaper Expresso that H5N1 is two mutations away from becoming easily transmissible person to person. The comment was widely repeated in news reports around the world. Reached Monday at Munich Airport, Nabarro explained he was echoing a theory he'd heard from Dr. Ab Osterhaus, the head virologist at Erasmus University in Rotterdam and a central player in the community of scientists tracking this virus. Osterhaus was slightly less definitive, but repeated the belief that "a couple" of key mutations might make the virus more efficient at jumping from birds to people, and then between them in limited fashion. Once that limited human-to-human spread started, he suggested, the virus might reasonably be expected to undergo additional changes that would allow it to flourish in its new host. It's thought that efficient human-to-human transmission of the virus would trigger a flu pandemic, the first since the Hong Kong flu of 1968. Still, Osterhaus admitted his theory is an educated guess at this point. "It would be a fair statement that it would not need many mutations for the virus to do that in principle. But we don't know that, actually. But it could well be," he said. His comments underscore the fact that despite decades of study, scientists are not clear what changes an avian influenza virus needs to undergo to fully adapt to humans. "The science is not there yet," said Adolfo Garcia-Sastre, a microbiologist who researches flu at Mt. Sinai School of Medicine in New York. Studies could be done that would chart a sort of roadmap for adaptation, he suggested, but researchers would first need to find an animal that could act as a surrogate for human infection. While it's believed ferrets could be that model, testing would be needed to validate that. Then viruses would have to be manipulated in order to try to determine what role each of a flu virus's eight genes play in transmissibility. "It's not quick," Garcia-Sastre said, noting this work would have to be done in high biocontainment laboratories. He wasn't willing to make an on-the-record prediction of how near or far H5N1 is from becoming a virus that easily infects people, though he privately named a figure that is significantly higher than Osterhaus's guess. "But it is complete speculation. So don't quote me," Garcia-Sastre said. � The Canadian Press, 2006 http://www.mytelus.com/news/article.do?pageID=cp_health_home &articleID=2170203