|
  
- 现金
- 3700 元
- 精华
- 16
- 帖子
- 1790
- 注册时间
- 2002-12-9
- 最后登录
- 2021-4-14
|
1楼
发表于 2005-2-27 02:21
An Advance in Fighting Hepatitis B
Source: Scripps Howard
Publication date: 2005-02-24
http://afjournal.yellowbrix.com/pages/afjournal/Story.nsp?story_id=65742244&ID=afjournal&scategory=Seafood+Industry&
Each year, about 350 million people worldwide are chronically infected with
hepatitis B virus. Spread through blood and other bodily fluids, this virus
puts them at high risk for cirrhosis, chronic liver disease and liver cancer
_ diseases that kill about 1 million people each year. Yet through the magic
of biotechnology, the lowly spud may change that.
For centuries, potatoes have saved lives with their nourishment. Now they're
tackling diseases spread by viruses and bacteria. Using potatoes with a
protein gene (called antigens) from HBV spliced into them, researchers have
produced high levels of immunity-providing antibodies in volunteers who ate
them. Their findings, reported in the Proceedings of the National Academy of
Sciences Online, should lead to vaccines that are cheaper, safer and easier
to deliver.
In the study, scientists from Roswell Park Cancer Institute in Buffalo,
N.Y., led by Dr. Yasmin Thanavala, fed volunteers small pieces of raw
potato. Some had "placebo potatoes," as it were; others received two doses
of genetically engineered potatoes and one dose of placebos, while the third
group ate only GE potatoes.
Nobody eating ordinary spuds developed extra hepatitis antibodies, while 53
percent of those who ate two doses of the GE ones did, as did more than 60
percent of the three-dose eaters. All recipients had previously gotten the
HBV vaccine series, so the potatoes simply boosted immunity they already
had. Some people developed antigen levels 50 times higher after eating the
super spuds.
That 60 percent level is still a far cry from the 90 percent to 95 percent
protection rate provided by the three-dose series of HBV injections, but
Thanavala is already working to improve the potatoes' immunogenicity to that
same level and in a single dose. One method comprises inserting more of the
viral antigen into the potato. Another would insert a harmless bacterium
into the potato as an adjuvant, an immune-system stimulator that helps
produce more antibodies.
Current HBV vaccines aren't particularly expensive to produce; the real
costs come from the need for refrigeration, injection by a trained person,
and using a fresh needle and syringe each time. That's no small potatoes
considering some studies have shown that the reuse of needles and syringes
in clinics may play a far larger role in the spread of HIV/AIDS in Africa
than is widely reported, since politically correct health officials wish to
focus only on vaginal sex.
Formerly, "edible vaccine" meant just that _ consuming vaccine foods
directly. But worries over medicinal strains getting mixed in with normal
food put the kibosh on that. So "edible vaccines" wouldn't really be eaten,
notes Thanavala. Rather, they would probably be powdered and ingested in gel
capsules.
Successful potato-vaccine experiments aren't new. Charles Arntzen of the
Biodesign Institute at Arizona State University has induced antibodies in
humans to both the diarrhea-causing Norwalk virus and the dreaded E. coli.
But these pathogens attack the stomach. Thanavala's antigens had to make it
past the stomach and into the bloodstream. That's what makes the process so
promising against so many diseases.
"I'm bowled over each time this works as well as it does," she told me.
"We've shown the antigen in plants is encapsulated in membranes and we
believe this allows it to survive stomach conditions until reaches the small
intestine." As such, she's given the entire field of plant-based vaccines a
boost _ and a large field it is. At least 45 different antigens have been
produced in a wide variety of plants to treat diseases affecting billions of
people.
A short list includes an HBV vaccine being grown in lettuce, a rabies
vaccine in spinach and tobacco, and an anthrax vaccine in tobacco and
lettuce. Texas-based ProdiGene is developing a corn-based HIV vaccine. You
probably don't know what hepatitis E is, but somebody is using tomatoes to
make a vaccine against it.
Thanavala wouldn't speculate when a potato-based vaccine might be available.
She wants to keep it in the lab until it meets all her goals. But that
recalls the axiom: " erfection is the enemy of the good." People are dying
now and this vaccine could get regulatory approval in just a few years.
It sounds like a cause for the Bill and Melinda Gates Foundation. Are you
listening, guys?
(Michael Fumento (fumento(at)pobox.com) is author of "BioEvolution: How
Biotechnology Is Changing Our World" and a senior fellow at the Hudson
Institute.)
?2004 Scripps Howard News Service.
To Post a message, send it t
[email protected]
~~~~~~~~~~~~~~~~~~~~~~
To Unsubscribe, send a blank message t
[email protected] |
|
