- "Anyone who is honest about this has to admit that
if al Qaeda launches a spectacular biological attack which could cause
contagious disease to be spread, no entity in the world is prepared for
it," Noble said. "Not the U.S., not Europe, not Asia, not Africa."
-
- Since the WSN/33 situation in Korea provides some valuable
insight into detection and reporting of bird or human flu, and wire services
are carrying stories about biologic attacks by terrorists causing a contagious
disease, it is worth reviewing some of the lessons learned from the swine
WSN/33 infections.
-
- If pandemic flu is the contagious disease of choice,
selection of WSN/33 at this time would offer some advantages. It is already
transmissible from human-to-human, has been shown to be lethal in mice,
has mutations in NA and PB2 that increase lethality, is widely available,
and could be used without genetic manipulation.
-
- As has been seen in Korea, introduction of the agent
into pigs would allow it to spread almost undetected. Verification of
its spread (or existence) has proven to be exceedingly difficult. Movement
from swine to humans has not been reported and all reported isolates are
missing the PB2 mutation. This may be due to a survival selection offered
by recombining or reassorting with prevalent H9N2 subtypes. Most of the
swine isolates have an avian PB2, but even the isolates that have half
of a human PB2 have the 3' half of the human gene replaced with avian sequences.
Thus, the results from the Korean swine may indicate that starting with
a very lethal virus has disadvantages in that a less lethal virus will
emerge virtually undetected.
-
- A second choice would be the H5N1 currently causing the
high case fatality rate in Vietnam, Thailand, and Cambodia. This version
would be even more available, since it is excreted in large amounts by
asymptomatic ducks, and is present in multiple organs in fatal infections.
Although human-to-human transmission of H5N1 is limited, infecting a few
international travelers would generate worldwide panic if these passengers
became ill outside of areas with indigenous H5N1. Use of infected currency
as a vector for transmission has been widely discussed.
-
- A third approach would involve genetic manipulation.
Creating an efficiently transmitted H5N1 would be relatively easy. Swapping
a human receptor binding domain from a human flu virus into an H5 backbone
would improve transmission efficiency and such an agent would quickly disseminate
worldwide. Of course such an agent would be hard to control, and most
unvaccinated people would be at risk. Since influenza evolves via recombination,
implementation of an efficient laboratiry strain might be eclipsed by a
natural version, and there would be uncertainty over the origins of such
an agent.
-
- Thus, like WSN/33 in Korean swine, taking credit for
such a biologic attack may be difficult, since most countries appear to
be unable to even determine if such an attack has happened.
-
-
-
- Webmaster: webmaster@recombinomics.com
- © 2005 Recombinomics. All rights reserved.
- http://www.recombinomics.com/News/02230501/Pandemic_Bioweapon.html
|
