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item Liu, Yanhong
item Fratamico, Pina

Submitted to: Molecular and Cellular Probes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2006
Publication Date: 3/14/2006
Citation: Liu, Y., Fratamico, P.M. 2006. E. coli o antigen typing using dna microarrays. Molecular and Cellular Probes. 2006. 20:239-244.

Interpretive Summary: The bacterium, Escherichia coli, causes a variety of diseases in humans and animals, and non-harmful types, or serogroups, also exist. A procedure called serotyping is commonly used to identify and distinguish between different E. coli strains. This procedure relies on the use of antisera raised in rabbits that react with different components of the bacterium. Serotyping, however, is laborious, time consuming, and often generates equivocal results due to cross-reactions between different serogroups. Furthermore, the antisera used for serotyping can only be generated in specialized laboratories with animal facilities. An alternative to serotyping using antisera is genetic typing based on the identification of unique genetic sequences found in genes that are involved in the production of the specific components that react with the antisera. DNA microarrays consist generally of glass slides onto which a number of different DNA sequences are spotted. This is followed by binding of labeled DNA of the specific bacterium being analyzed. A measurable fluorescent signal results if the labeled DNA binds to a complementary sequence on the glass slide. Model DNA microarrays were developed for typing E. coli. The advantages of this novel method are that it is rapid, and simple, and involves only one assay compared to numerous reactions required when using antisera for the identification of the serogroup of the E. coli strain. DNA microarray-based assays will potentially allow rapid detection and identification of other food-borne pathogens, as well.

Technical Abstract: DNA microarrays were developed for rapid identification of different serogroups of E. coli in a single platform. Oligonucleotides, as well as PCR products from genes in the O-antigen gene clusters of E. coli serogroups O7, O104, O111, and O157 were spotted onto glass slides. This was followed by hybridization with labeled Long PCR products of the entire O antigen genes clusters of these serogroups. Results demonstrated that microarrays consisting of either oligonucleotides or PCR products generated specific signals for each serogroup. This is the first report describing the development of model DNA microarrays for determining the serogroup of E. coli strains.