Researchers from a national security laboratory in the U.S. have announced a technology which can detect the presence of thousands of microorganisms in just 24 hours. Hundreds of thousands of probes on a 1 x 3 inch glass slide can look for the entire range of known viruses and bacteria in a single test, which could prove invaluable in product safety testing, medical diagnosis and bioterrorism detection and prevention.

Research team Tom Slezak, Crystal Jaing, Shea Gardner, Kevin McLoughlin, James B Thissen of California's Lawrence Livermore National Laboratory (LLNL), a national security laboratory managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration, announced the findings last week.

Team leader Slezak came up with the idea for the Lawrence Livermore Microbial Detection Array (LLMDA) in 2003, but its development didn't begin until late 2007. Any virus or bacteria that has been sequenced and included amongst the array's 338,000 tiny probes, that are squeezed onto a semi-transparent glass slide measuring just one inch by three, can be detected in just 24 hours. Unlike current methods, which are limited to detecting pathogens from a range of about 50 or so, the LLDMA can detect numerous pathogens in a single test from the entire range of known viruses and bacteria.

The process begins with the purification of DNA and RNA from a sample. The sample is labeled with a fluorescent dye and hybridized onto an LLMDA slide at 42ºC. Then a scanner linked to analysis software looks for probes that have lit up, so identifying any pathogens present. It is intended that the system's database be regular updated with new microbe sequences from public databases like GenBank as well as university and authority sources from around the globe, such as the U.S. Food & Drug Administration, the Statens Serum Institut of Copenhagen, Denmark and the University of Texas Medical Branch.

"For each bacteria or virus that has been sequenced anywhere in the world, we have several dozen squares on the checkerboard that will identify sequences from that organism," explained Slezak. The current operational version can detect more than 2,000 viruses and some 900 or so bacteria and in addition to looking for high-risk pathogens detected using current polymerase chain reaction systems, the LLMDA can look for "any other already-sequenced bacteria or virus in a sample that you might not have been expecting to find, including possible novel or emerging pathogens."

The researchers are currently testing a new version of the technology which includes over two million probes representing about 178,000 viral sequences from some 5,700 viruses, about 785,000 bacterial sequences from thousands of bacteria and also contains about 237,000 sequences from thousands of fungi and over 200,000 from 75 protozoa.

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