Medical professionals diagnosing diseases, law-enforcement authorities dealing with an apparent bioterrorism attack, and regulatory agencies testing product safety may have a new detection tool to add to their arsenal: the Lawrence Livermore Microbial Detection Array (LLMDA). Designed by a team of Livermore biologists and informatics specialists, LLMDA can simultaneously identify thousands of known viruses and bacteria within 24 hours.
Current detection systems, such as polymerase chain reaction (PCR) technologies, focus on small, prioritized sets of high-risk biological pathogens. LLMDA, however, can identify a broad range of organisms, including pathogens on a priority screening list, sequenced bacteria or viruses that might not be anticipated, or even emerging pathogens containing DNA sequences previously identified in other pathogens. LLMDA is less expensive than sequencing and more inclusive than PCR analysis. It can identify any sequenced virus and bacterium. The microarray’s checkerboard has several dozen squares for each of the thousands of organisms sequenced to date, so it can simultaneously examine multiple regions from each organism.
The LLMDA process begins by purifying DNA or RNA from a blood or stool sample. The purified DNA or RNA is labeled with a fluorescent dye and then squirted onto the microarray, which sits on top of an incubator heated to 42°C. The microarray contains nearly 400,000 probes arranged in a checkerboard pattern on a 2.5- by 7.5-centimeter glass slide. Scientists examine these probes using a fluorescent scanner and analysis software.
LLMDA has great potential for improving processes used by medical professionals, law-enforcement personnel, and product manufacturers. Deploying LLMDA in these different applications could better prepare the nation when the next outbreak from an unknown pathogen hits.