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Politics : Ask Michael Burke -- Ignore unavailable to you. Want to Upgrade?

To: Knighty Tin who wrote (93637)	12/18/2001 8:58:28 AM
From: JHP	Read Replies (2) \| Respond to of 132070

Monday December 17, 09:56 PM Mice produce malaria vaccine in milk - U.S. report By Maggie Fox, Health and Science Correspondent WASHINGTON, Dec 17 (Reuters) - Genetically engineered mice have produced a malaria vaccine in their milk that worked to protect monkeys from the disease, U.S. researchers said on Monday. They said their experiment shows that animals can be used to produce cheap and plentiful vaccines, and if the experiment worked in larger animals such as goats, enough vaccine could eventually be produced to immunize as many as 20 million people a year. A company working with the researchers, Genzyme Transgenics Corp. of Framingham, Massachusetts, has already bred two genetically engineered goats that seem to produce the protein in their milk. "A vaccine must not only be effective, it must be cheap to manufacture if it is to be used in those countries hit hardest by malaria," Anthony Stowers, a malaria researcher at the National Institute of Allergy and Infectious Diseases (NIAID) who led the research, said in a statement. "If it works, a herd of several goats could conceivably produce enough vaccine for all of Africa." Malaria, which kills 2.7 million people each year, is caused by a parasite carried by a mosquito. There are treatments but no vaccine. Stowers warned that the experiment will not lead to a malaria vaccine for people any time soon. "How it will go in people is very problematic," he said. "Most successful vaccines are attenuated vaccines -- they are made with a weakened or killed version of whatever you are vaccinating against." His team's vaccine uses a single protein from the malaria parasite, and he said the vaccine only worked in monkeys because the vaccine was revved up with extra ingredients called adjuvants that overstimulate the immune system and are considered too dangerous to use in people. The World Health Organization estimates there are 500 million cases of malaria each year, 90 percent of them in Africa. Stowers, Louis Miller and colleagues at NIAID and Genzyme created mice genetically engineered to produce a little piece of the parasite that causes malaria, Plasmodium falciparum, in their milk. Such a protein is known as an antigen because it stimulates antibodies in the immune system to recognize and move in against an intruder. The researchers designed the parasitic gene to be switched on by the cells that line the mammary glands in the mice so that the resulting proteins would be secreted into their milk. They got a good production of the protein from the mice, and when they immunized laboratory monkeys with it, four out of five monkeys were protected against malaria, the researchers reported in Tuesday's issue of the Proceedings of the National Academy of Sciences. The next step would be to try this in goats, which produce more milk than mice do. If it works, each animal would be a vaccine production factory, they said. Stowers said Genzyme had bred two young female goats that carry the parasite's gene. "The goats are too young to be naturally lactating but they can induce lactation for a very brief period of time and they have done that," he said. The goats, Stowers said, produced the same amount of protein as the mice did. "Up to 700 liters (185 gallons) of milk per year can be obtained from a single goat, with potential production levels of between one to 10 grams of protein per liter of milk," his team wrote. "A single goat producing 700 liters a year of milk at the yields we obtained could supply enough antigen to vaccinate 8.4 million people annually. ... Thus a herd of three goats could conceivably produce enough antigen to vaccinate 20 million African children a year." There is currently no malaria vaccine, although many groups are working on one. Malaria is very hard to vaccinate against because people do not naturally become immune to it, Stowers said. "If you get measles, you are immune," he said. Thus there is an effective measles vaccine. "With malaria, people don't get natural immunity. They can be repeatedly infected throughout their lives and are."