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HOST GENE CELL RESEARCH FOR DETERMINING VIRULENCE OF AEROMONAS SPP. COLLECTED FROM ENVIRONMENTAL SAMPLES
Citation:
HAYES, S. L., D. J. LYE, M. R. RODGERS, G. N. STELMA, AND S. J. VESPER. HOST GENE CELL RESEARCH FOR DETERMINING VIRULENCE OF AEROMONAS SPP. COLLECTED FROM ENVIRONMENTAL SAMPLES. Presented at IMUS 2005, San Francisco, CA, July 23 - 28, 2005.
Impact/Purpose:
To inform the public
Description:
The United States Environmental Protection Agency (USEPA) is interested in assessing health risks associated with emerging or potential waterborne pathogens. To this end, the Agency has established a Candidate Contaminant List (CCL) that includes Aeromonas hydrophila and other microorganisms slated for exposure and risk research. The intent is to establish a direct correlation between specific organisms present in a source or finished water sample and disease potential. Current practices of using indicator organisms (e.g., total or fecal coliforms) have obvious limitations. With the emergence of molecular methodologies, it is now possible to discriminate whether a water sample has disease potential based on its microbial content. DNA microarrays are being developed that can detect species-specific DNA or virulence factors (VFs). Disadvantages of this approach include viability assessment, the need to amplify target sequences, the need to develop extensive databases of sequences and the uncertainty of which combination of VFs are required for disease. To circumvent these limitations, research using eukaryotic host cell responses to infection by specific waterborne pathogens has been initiated. Using live animal and cell culture models and microarrays, gene expression data provide distinctive mRNA patterns for discerning infections from virulent and avirulent species within the bacterial genus Aeromonas. Virulent Aeromonas spp. produce a large number of upregulated mRNAs in both small intestinal tissue from infected neonatal mice as well as in mouse intestinal cell (MIC) monolayers. Avirulent strains exhibit little gene upregulation in live animals and altered patterns in MIC cultures as compared to virulent strains. Many A. hydrophila and A. veronii biotype sobria isolates from a water distribution system survey cause large (200-400 transcripts) upregulation of genes associated with the immune response in neonatal mice (chemokine production, activation of transcription [e.g., NF-kB pathway], cell adhesion molecules). Strains from avirulent species (A. caviae and A. allosaccharophila) do not cause significant gene upregulation in this same model. Also, distinction of avirulent/virulent isolates within a species (A. veronii biotype sobria) has been demonstrated. The end goal of this research is to find a suitable model for assessing disease potential of a water sample to humans based on host cell response.