Guest guest Posted May 11, 1999 Report Share Posted May 11, 1999 -----Original Message----- From: & Robynn <nebneb@...> >> >> I do not know what this means for Lyme, but I found it good reading >> anyway... >> >> >> ------------------------------------------------------------------------- - >-- >> -------- >> >> WASHINGTON (AP) -- In a discovery that could lead to powerful new vaccines >> and antibiotics, researchers have isolated a key gene that bacteria use to >> launch killer infections. >> >> Researchers at the University of California, Santa Barbara, have >> demonstrated in laboratory studies that removing or inactivating a gene >> called DAM can disarm a strain of salmonella, bacteria that cause food >> poisoning in humans. >> >> " We've uncovered a genetic master switch that controls bacterial >> infection, " said Dr. J. Mahan, the study's lead author and a UCSB >> professor. " When we knock out this switch, the bacterium is completely >> disabled in its ability to cause disease. " >> >> The study is to be published Friday in the journal Science. >> >> Mahan said the DAM gene was found through a five-year process of examining >> bacterial genes that are turned on at the start of an infection in a host >> animal. Often these genes are quiet in laboratory dishes and go into >action >> only when the pathogen is starting an infection inside an animal. >> >> " Bacterial pathogens act like a Trojan horse -- they hide their weapons >> until they are within an animal, " said Mahan. As a result, some bacterial >> genes that cause infection " are turned on inside a mouse and off outside a >> mouse, " he said. >> >> The UCSB researchers, using salmonella, found that the DAM gene made a >> protein that turned on other genes that started the infection process. >> >> When strains of salmonella were created that permanently disabled the DAM >> gene, the microbe could not cause disease in mice. >> >> The altered bacteria also acted like a vaccine, causing the mouse's immune >> system to make antibodies that would attack salmonella, said Mahan. >> >> " Mice immunized with this crippled strain of salmonella were completely >> protected from infection, " he said. Some of the mice were injected with a >> salmonella dose 10,000 times more powerful than a dose that is lethal to >> half of all mice. None of the animals developed disease, said Mahan. >> >> There are 2,500 strains of salmonella that cause diseases ranging from >food >> poisoning to typhoid fever. Poorly cooked poultry and eggs are a common >> source of salmonella food poisoning, and some experts have estimated that >> up to 4 million Americans are affected annually. >> >> A variety of other bacteria pathogens, including cholera, plague and >> Shigella dysentery, also have DAM genes, raising the possibility that >those >> diseases could also be disabled by blocking DAM. >> >> Mahan said it may be possible to make an antibiotic based on the DAM gene. >> If a chemical could be found that blocks the action of the protein made by >> DAM, then it might prevent bacteria from continuing the infection process, >> he said. >> >> " This is a breakthrough discovery, " said Dr. Philip Hanna, a >microbiologist >> at Duke University Medical Center. " They have found a master switch that >> turns on virulence. " >> >> If further study proves that disabling the DAM genes will protect humans >> from bacterial infection, it could lead to a new class of antibiotics and >> to a new type of vaccine, Hanna said. >> >> But Dr. Regina Rabinovich, a scientist at the National Institute of >Allergy >> and Infectious Diseases, a part of the National Institutes of Health, >> cautioned that the value of the DAM research will not be known until it is >> tested and proven to work in humans. >> >> " The mouse has not been a very good model for what will happen with >> salmonella in humans, " said Rabinovich. >> >> Medical researchers are scrambling to find new ways of combating >infections >> that now claim about 17 million lives annually worldwide -- almost three >> times the death toll of cancer. Many antibiotics that once worked are no >> longer effective against evolving strains of bacteria. Even vancomycin, >the >> " last hope " antibiotic that once was invariably effective, has recently >> encountered germs it cannot control. >> >> " We are about to re-enter the pre-antibiotic era because there are >pathogen >> strains now that are resistant to every available antibiotic, " said Mahan. >> " This (altering the DAM gene) may buy us some time. " >> > > Quote Link to comment Share on other sites More sharing options...
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