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Although many different strains of Listeria monocytogenes can contaminate food, not all appear to be equally capable of causing disease. A small number of antigenic types (serotypes) account for the majority of strains implicated in human illness. Of these, serotype 4b is of special interest, being involved in almost all common-source outbreaks of listeriosis and in numerous sporadic cases. We have identified two gene clusters unique to serotype 4b strains and essential for the expression of serotype-specific antigenic components on the bacterial cell wall.
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We propose to complete the molecular characterization of these regions in order to gain novel information on the serotype-specific genes and in order to identify DNA-based diagnostic reagents for this serotype. We will also investigate the possible involvement of serotype-specific determinants in pathogenesis, using endothelial cells as a biologically relevant model system.
Listeria monocytogenes is a troublesome food-borne bacterial pathogen because of its ubiquitous distribution, its ability to grow in refrigerated foods, and its involvement in severe and often fatal illness (listeriosis). Pregnancy, immunosuppression, and extremes of age are predisposing conditions, and ready-to-eat, refrigerated foods have been frequently implicated in infection. Contamination of ready-to-eat foods by Listeria, including dairy and meat products, also accounts for numerous and costly food recalls, thus rendering the microorganism a severe threat both to public health and to agriculture. Such investigations may yield novel molecular reagents that will facilitate monitoring and detection of clinically important strains of the pathogen, and may further elucidate the virulence attributes of such strains.
University of Hawaii if the Cooperative Institution