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The Good, the Bad and the Ugly Determination of Bacterial Virulence Using Animal Models and Microarray Technology

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Abstract:In its Computational Toxicology Program, EPA/ORD proposes to integrate genomics and computational methods to provide a mechanistic basis for the prediction of toxicity of chemicals and the pathogenicity of microorganisms. The goal of microbiological water testing is to be able to determine with scientifically sound probabilities that the consumption of and/ or exposure to a given volume of water is safe. At present, the US EPA relies on indirect methods to determine the probabilities of the safety of drinking water, for example, the detection and enumeration of indicator microorganisms (e.g. E. coli ). Although the concept of indicator organisms as a measure of risk has served to reduce water-borne disease significantly over the years, public health professionals generally agree that the presence of pathogens does sometimes escape detection and at an unknown frequency.

Municipally treated drinking water is known to contain many bacteria, whose identity and potential human virulence is poorly understood. In some cases pathogens may not be culturable by our standard methods. In addition, polymicrobial disease agents may be present. Polymicrobial diseases are infections that result from multiple co-infecting organisms as opposed to a single microorganism. Application of computational-toxicologically based DNA microarrays offers a totally new approach to address the issue of water-borne pathogens.

There are many potential human pathogens in potable water, some identified and some not yet identified. In order to cause disease, a pathogen must possess "virulence factors" that interact with a host cell to cause damage that results in disease. The interaction with a host cell results in a change in the metabolism and thus the messenger RNAs (mRNAs) that are produced by the human cell(s). These changes can be monitored using Human DNA microarrays which will reveal whether a pathogen is present and whether it is virulent.

Ultimately, we will build a database of these mRNA responses to more and more known pathogens and the virulence factors associated with inducing the mRNAs. It may be possible to then use this database to predict the potential pathogenicity of unknown or non-culturable pathogens based on their producing similar mRNA responses found in known pathogens. Some animal experiments may then be used to confirm these predictions. However, ultimately this type of analysis should dramatically reduce the EPA's need for animals in experimentation.

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Citation:Rodgers, M. R., S. J. Vesper, and D. Lye. The Good, the Bad and the Ugly Determination of Bacterial Virulence Using Animal Models and Microarray Technology. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
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Contact: Mary P. O'Bryant - (919)-541-4871 or obriant.mary@epa.gov
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Division: Microbiological & Chemical Exposure Assessment Division
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Branch: Microbial Exposure Research Branch
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Product Type: Abstrct/Oral
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Presented: 05/05/2003
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Related Entries:
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Bullet Item Evaluation of Dna Chips (Microarrays) for Determining Virulence Factor Activity Relationships (Vfars)
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