New technique differentiates among genes of Listeria DNA.A new tool may be at hand for subtyping strains of L. monocytogenes which cause foodborne illness. Subtyping determines the strain affiliation of Listeria Listeria /Lis·te·ria/ (lis-ter´e-ah) a genus of gram-negative bacteria (family Corynebacterium); L. monocyto´genes causes listeriosis.
n. specimens isolated in the lab. This is critical to epidemiologists tracing outbreaks back to their source, as well as to government and industry efforts to safeguard food supplies through environmental monitoring, disinfection disinfection,
n the process of destroying pathogenic organisms or rendering them inert.
disinfection, full oral cavity,
n a procedure used to reduce active periodontal disease, usually completed within a certain short time frame. , sanitation and other measures.
In the United States, listeriosis Listeriosis Definition
Listeriosis is an illness caused by the bacterium Listeria monocytogenes that is acquired by eating contaminated food. The organism can spread to the blood stream and central nervous system. sickens an estimated 2,500 people annually, and it kills 500. Of the bacterium's 13 known strains, serotypes 1/2a, 1/2b and 4b are chiefly to blame for the illness. Epidemiological studies and analysis of putative virulence genes have shown that L. monocytogenes has diverged into several phylogenetic divisions. The researchers believe that similar divergence has occurred for many genes that influence niche-specific fitness and virulence. Identifying these differences may offer new opportunities for the detection, treatment and control of this important pathogen.
In Pullman, WA, USDA-ARS USDA-ARS United States Department of Agriculture-Agricultural Research Service scientist Monica Borucki and Washington State University Washington State University, at Pullman; land-grant and state supported; chartered 1890, opened 1892 as an agriculture college. From 1905 to 1959 it was the State College of Washington. scientists Douglas Call and Thomas Besser devised a technique--mixed genome microarray analysis--to examine the DNA DNA: see nucleic acid.
or deoxyribonucleic acid
One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. of L. monocytogenes for genes that differ among its strains. Identifying the genes will help the researchers learn why some strains cause disease epidemics, while others don't. This approach also will help them design subtyping methods for identifying the most pathogenic strains. These techniques could then be used to check for genetic evidence of the strains in food, on farms or on food-processing equipment.
In studies recently published in the Journal of Clinical Microbiology The Journal of Clinical Microbiology is an academic journal published by the American Society for Microbiology. The title is commonly abbreviated JCM and the ISSN is 0095-1137 for the print version, and 1098-660X for the electronic version. , the research team extracted DNA fragments from 10 representative Listeria strains. The investigators printed copies of them--in the form of hundreds of tiny dots, called microarray probes--onto microarray slides. Next, they used fluorescence to label the DNA of the strains they wished to subtype, or genetically characterize.
The labeled DNA was applied to the slide, where it bound to probes with similar DNA. Computerized imaging software enabled the team to examine the slides for DNA illumination patterns signaling the presence of subtype-specific genes.
Eventually, the scientists hope to parlay their microarray gene discoveries into a fast, standardized method of subtyping that health labs can use to compare large amounts of data on strains that may cause local or national epidemics.
Further information. Monica Borucki, USDA-ARS Animal Disease Research Unit, 3003 ADBF ADBF Asian Dragon Boat Federation
ADBF Adaptive Digital Beamforming , Washington State University P.O. Box 646630, Pullman, WA 99164; phone: 509-335-7407; fax: 509-335-8328; email: email@example.com.