 |
MADISON - Using a gene resurrected from the virus that caused the 1918 Spanish influenza pandemic, recorded history's most lethal outbreak of infectious disease, scientists have found that a single gene may have been responsible for the devastating virulence of the virus.
Writing Oct. 7 in the journal Nature, virologist Yoshihiro Kawaoka of the University of Wisconsin-Madison and the University of Tokyo, describes experiments in which engineered viruses were made more potent by the addition of a single gene. The work is evidence that a slight genetic tweak is all that is required to transform mild strains of the flu virus into forms far more pathogenic and, possibly, more transmissible.
The results of the new work promise to help scientists understand why the 1918 pandemic, a worldwide outbreak of influenza that killed 20 million people, spread so quickly and killed so efficiently, says Kawaoka, who has studied influenza viruses for 20 years. The finding also lends insight into the ease with which animal forms of the virus, particularly avian influenza, can shift hosts with potentially catastrophic results.
"Replacing only one gene is sufficient to make the virus more pathogenic," says Kawaoka, a professor of pathobiological sciences at the UW-Madison School of Veterinary Medicine. In the Nature paper, Kawaoka and his colleagues describe how a Spanish flu gene that codes for a key protein changed a relatively benign strain of flu virus from a nuisance to a highly virulent form.
In the late 1990s, scientists were able to extract a handful of genes from the 1918 virus by looking in the preserved lung tissue of some of the pandemic's victims. Subsequently, the genes were sequenced, including two critical genes that make hemagglutinin and neuraminidase, the protein keys that help the virus enter and infect cells.
Using a comparatively mild form of influenza A virus as a template, Kawaoka's team added the two 1918 genes that code for hemagglutinin and neuraminidase and infected mice with the engineered viruses.
"Here we demonstrate that the [hemagglutinin] of the 1918 virus confers enhanced pathogenicity in mice to recent human viruses that are otherwise non-pathogenic in this host," Kawaoka and his colleagues write in the Nature report. Moreover, the viruses with the 1918 hemagglutinin gene caused symptoms in the mice - infection of the entire lung, inflammation and severe hemorrhaging - eerily similar to those exhibited by human victims of the 1918 pandemic.
Another important result of the new study is that it supports the idea that the 1918 Spanish flu virus was avian in origin, but already adapted to proliferate in humans. That insight is important as scientists and public health officials view birds as a primary reservoir of influenza A virus, strains of which can sometimes jump species to infect other animals, including humans.
|
Oct 4, 2004 (CIDRAP News) – A young girl who died Sunday night is Thailand's 11th avian influenza victim, a health ministry spokeswoman told news services on Monday.
The girl's H5N1 infection had just been confirmed on Sunday. She was from the northern Thai province of Phetchabun and had been in the hospital for about a week, Reuters news reported. Reports put her age at 8 or 9 years old.
Her death comes at a time of heightened surveillance and political pressure. Thai Prime Minister Thaksin Sinawatra on Sep 29 threatened to fire a deputy prime minister, as well as the health and agriculture ministers, if the virus isn't eradicated in a month, news agencies have reported.
The Thai government has begun ordering up to 1 million officials and volunteers to inspect every village for flu symptoms among people and birds, the state-owned radio reported on Oct 1.
The approach of migratory bird season has added fresh urgency to such efforts because the wild birds can carry the virus and spread it.
During the weekend, Thai officials believed that scientists had found avian flu in dogs. Officials on Sunday said they had confirmed the first case of avian flu in a dog but later rescinded the announcement. The positive result in one round of testing may have been due to a sampling error, a health ministry spokesperson said in The Nation newspaper of Thailand. A second test indicated the dog did not have avian flu. The dog in question will be rechecked, authorities told the paper.
The spread of the virus among mammals heightens concern about transmission to humans. The World Health Organization (WHO) has said that only pigs could harbor both avian and human flu strains. That can create the opportunity for the viruses to combine, which could foster conditions for a human flu pandemic.
The dog flu tests come only weeks after a Dutch report found that cats can contract H5N1 influenza and an earlier report from China that the virus had been detected in some pigs. A leopard and a tiger at the Bangkok zoo were confirmed with the virus last February, reports said.
|
These are good times for those who grow and sell organic foods. But there may be trouble in paradise.
Prompted by a quest for safer, healthier diets and a cleaner environment, more American consumers are buying the bountiful harvests of organic farmers. Last year, U.S. spending on organic foods reached close to $10.4 billion, making this the fastest-growing segment of the American food industry. Amid scares over mad cow disease, mercury in fish and produce tainted with harmful bacteria, new customers are joining existing ones in embracing organic foods as a sanctuary.
But as organic products — and their claims to superiority — have grown more common, scientists, policy analysts and some consumers have begun to ask for proof. Where’s the evidence, they ask, for the widespread belief that organic foods are safer and more nutritious than those raised by conventional farming methods?
The short answer, food safety and nutrition scientists say, is that such proof does not exist. Indeed, by one well-established measure of healthfulness — contamination with fecal matter and potentially harmful bacteria — some organic foods may pose greater risks to consumers.
As food fights go, this one might not be as raucous as the cacophony over low-carb diets or reshaping the food pyramid — yet. But since 1989, when organic-food activists raised a nationwide scare over the pesticide alar in apples, many scientists have seethed quietly at what they perceive as a campaign of scare tactics, innuendo and shoddy science perpetrated by organic food producers and their allies.
|
Scientists and environmentalists continue to be at loggerheads over a genetically modified strain of rice developed in Switzerland.
Its supporters say “golden rice” is a milestone in the history of genetic engineering, but opponents have accused them of making empty promises.
“This is intellectual fraud,” said Clément Tolusso, press officer for the environmental group, Greenpeace, in western Switzerland.
The continued debate over the pros and cons of golden rice comes as the United Nations celebrates the International Year of Rice.
In 2000 a group of researchers at the Federal Institute of Technology in Zurich succeeded in transmitting to a grain of rice the ability to produce beta-carotene – which the body coverts into vitamin A – and to increase iron content.
In Asia, where rice is the main food for millions of people, vitamin A and iron deficiency is a serious problem.
These essential dietary components are found in animal products, fruits and vegetables, which are not always available to poor families.
A lack of these nutrients can cause anaemia, vision loss or a weakened immune system, and is one reason for the high rate of mortality and illness among women and children in developing countries.
Malnutrition
Those behind golden rice believe the genetically modified organism (GMO) marks an important step in the fight against malnutrition.
“The idea is to provide a food that can at least partially make up for these deficiencies,” Rainer Holzinger, a scientist at the Institute for Plant Sciences at the Swiss Federal Institute of Technology in Zurich, told swissinfo.
But critics of golden rice and GM foods in general argue that these products are not the answer.
“The problem is not that there isn’t enough food for everyone,” says Tolusso. “It has to do with the accessibility and stockpiling of food.”
|
Plant geneticist Ted Hymowitz knew that finding an allergy-free soybean would take a painstaking search through thousands of varieties. So Hymowitz got a grant, fetched a hammer and pounded away until he proved he was right.
Hymowitz and fellow University of Illinois researcher Leina Mary Joseph found a seed that lacks the protein, known as P34, responsible for most allergic reactions. It took them about eight months of crushing seeds from thousands of varieties in the U.S. Agriculture Department's soybean germplasm collection at the university.
"This thing is so rare that you need the huge collection to find the needle in a haystack," Hymowitz said.
Scientists already had used genetic engineering to silence the gene that creates P34 in most soybeans. But it likely will be much easier to market soybeans that naturally lack the protein, said Eliot Herman, the USDA researcher who developed the biotech bean two years ago.
While much testing remains before farmers can grow allergy-free soybeans, Hymowitz's research shows promise for people who are allergic, said Anne Munoz-Furlong, founder of the Food Allergy and Anaphylaxis Network based in Fairfax, Va.,
About 11 million Americans have some type of food allergy, according to the network, and several studies indicate 6 to 8 percent of children and 1 to 2 percent of adults are allergic to soy. Soy is one of the eight most allergenic foods, and the number of people with soy allergies is expected to rise as the use of soy in many foods increases.
|