Posted on 03/22/2006 11:31:22 AM PST by blam
Bird flu's human-attack pathway revealed
18:00 22 March 2006
NewScientist.com news service
Debora MacKenzie
Two separate research groups have independently discovered why the H5N1 bird flu virus causes lethal pneumonia in people, but is – so far – hard for people to catch. In the process, they have found a way to predict which mutations might make the virus more contagious, and potentially become a pandemic strain. To date, confirmed human deaths from the disease stand at 103 worldwide
The H5N1 virus binds to sugars on the surface of cells deep in human lungs, but not to cells lining the human nose and throat. So report the two research teams, led by Thijs Kuiken at Erasmus University in Rotterdam, and Yoshihiro Kawaoka at the Universities of Tokyo, Japan and Wisconsin at Madison, US.
This fits the few autopsies that have been performed on H5N1 victims, who had damage to the alveoli – the delicate sacs deep in the lungs, where oxygen enters the blood.
Flu normally travels between people by being sneezed out and breathed in through the nose and throat. Both groups concluded that poor binding of the H5N1 high in the respiratory tract might be why the virus has so far not been able to spread easily between people – a major factor keeping it from becoming pandemic.
Deep inside
The Wisconsin team used lectins – plant molecules that bind to the same complex sugars on the cell surface where the flu virus attaches to cells – to identify how different versions of the sugar molecule vary in humans. They used one lectin specific to the "2,3 form" of the sugar common in birds – which H5N1 is known to prefer, and another specific to the "2,6 form" more common in people.
Testing tissue slices from the human respiratory tract, they found that 2,6 receptors were common in the nose and throat, but 2,3 receptors – H5N1’s preferred site – were common in the alveoli.
The Dutch group used the killed H5N1 virus itself, and saw the same pattern as the Wisconsin team, with binding in the deep lungs but not the nose and throat.
Repair hijack
Both groups found these receptors, or viral binding, especially in cells called type 2 alveolar cells. These actively dividing cells repair and maintain the tiny lung sacs, so H5N1’s binding of these particular cells might explain why H5N1 pneumonia is so severe. The virus can also hijack the machinery it needs to replicate more easily in these active cells than in neighbouring, non-dividing cells.
The Dutch team also found binding to alveolar macrophages – white blood cells which can trigger the inflammatory immune reaction, which often kills in pneumonia cases.
Their technique might allow scientists to predict what H5N1 could do next. “We will now try to look at what mutations in the virus improve binding in the upper respiratory tract,” Kuiken told New Scientist. That could show what mutations to watch for as H5N1 continues to spread around the globe.
They will also study which other human tissues H5N1 can bind to. Cases so far suggest it might affect the gut and most worryingly, the brain.
Journal reference: Nature (vol 440, p 435) and Science (DOI: 10.1126/science.1125548)
Maybe the lab needed some crash test dummies....
I have friends who are NOT normally "nutty" who are actually stockpiling food in the event a flu becomes widespread and food supplies are interrupted. I can't say that's not overdoing it, but I know the idea is out there.
I had heard that this 7-day emergency preparedness is a good idea, all the time. The man being interviewed had said that for people in the Dakotas and Colorado this is the norm, in case they get snowed in.
My trouble is, I never learned to 'shop ahead' for groceries. I'm always needing something I have put aside for something else. This is why I have 2 cans of pumpkin but no cake mix...
Good point!
Seven days' supply sounds like a good idea at any time, I agree.
"I have friends who are NOT normally "nutty" who are actually stockpiling food in the event a flu becomes widespread and food supplies are interrupted. I can't say that's not overdoing it, but I know the idea is out there."
Considering the low cost of a stash of emergency provisions (what - no more than $500 or so, depending on family size), I'd say it's a pretty decent idea. If nothing happens, you're always prepared for the worst and we know that we can't rely on the gov't (State or Fed) for help in event of calamitous emergency.
What's not being said (but should be) is to stock up on ammunition. Temporary, localized anarchy is an obvious possibility if the dire predictions come to fruition.
"Did you have a chance to read the unabridged version of The Stand? The original release had 400 pages of it redacted. The subsequent release after the movie included the extra 400 pages."
Oh yeah. Twice! Honestly, reading about the journey thru the Lincoln Tunnel was far worse than seeing it in the movie! I wasn't a huge fan of the ending, but loved the first 80% of the book.
I thought the casting of Tom M-O-O-N-spells-MOON! Cullem (spelling?) was spot-on! The "deaf and dummy", as Julie called him in Vegas.
Ummmmm.... I think the article indicates that the follow on condition is usually assuming room temperature.
Seven days supply is better than none, but it's only good for "seven" days.
There are newspaper reports following the HHS multi-state pandemic preparedness road show (now being given nationwide to State Emergency Managers) saying HHS is recommending a minimum of six weeks preparations because of possible widespread and lengthy quarantines. I have heard of a report where the Red Cross is recommending four weeks prep.
I don't know about you, but I would get the nasty hungries on the 8th day of an extended quarantine if I only had a seven day supply. I don't think I could last another five weeks munching on my boiled shoe leather.
At the risk of getting PETA on my case, wouldn't it seem the logical route if they know where approximately all these birds are flying to set up a catch and relase system where they catch these birds, put them through a vigorous testing and possible extermination process and any birds cleared of the disease can continue on afterwards.
they have found a way to predict which mutations might make the virus more contagious,
'He left her a dollar tip crawling with death.'
Sad, but true.
Understood! I have heard four months for this, if the worst happens.
For reference purposes:
http://www.freerepublic.com/focus/f-news/925970/posts
Strange new disease outbreaks
various FR links | 06-09-03 | The Heavy Equipment Guy
http://www.freerepublic.com/focus/f-news/1399613/posts
Avian Flu Surveillance Project
Various ^ | May 9, 2005 | Vanity
http://www.freerepublic.com/focus/f-news/1413888/posts
Marburg Surveillance Project Thread II
Various | May 31, 2005 | Vanity
http://www.freerepublic.com/focus/f-news/1507830/posts
Hurricane Preparedness ( and general "bad times" links )
various FR links & stories | 10-23-05 | the heavy equipment guy
The problem seems to be these are migrating birds and they are impossible to catch except for some samples.
The major flyway from Alaska through the western USA is the likely route of infection. Alasan wildlife authorities are now doing sampling. Siberian birds migrate to Alaska and then mix with the Alaskan birds. Siberia flocks are infected, so it is only a matter of time before we are infected, probably later this year. Then these infected migrating fowl will inevitably mix with our more stable bird populations and the dance goes on as this thing spreads.
H5N1 is coming here and will be a long term problem, not something we can solve by extermination of wild flocks - or even domestic flocks. The first question is, will it mutate to something which can readily be passed human to human instead of only bird to human? Second, will we have time to develop our medical defenses (vaccines) in time to face and prevent pandemic.
Authorities say the answer to #1 is "possibly/probably", and the answer to #2 is still "years away". So we will have to live with this looming threat for a quite while.
"In her report titled The Avian Flu Crisis: An Economic Update, Dr. Cooper explains that, unlike other natural disasters or terrorism, pandemics are prolonged and pervasive, so the net economic loss is substantial and extended. She states that an avian flu pandemic would lead to considerable supply and demand effects. Widespread absenteeism and trade disruption would dominate the supply-side effect, and social distancing and fear would initially increase the demand for essentials such as non-perishable food, water, medical supplies and health-care services, but reduce the demand for virtually everything else. "
Bird Flu Ping.
It it mutates so that it's easier to catch with contact to the nose or mouth, perhaps that it would mean that it would be less destructive to the lungs.
That would be my hope.
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