Submitted to: Applied and Environmental Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/30/2007
Publication Date: 3/10/2007
Citation: Paoli, G., Brewster, J.D. 2007. A listeria monocytogenes-specific single chain antibody bidns to the actin polymerization protein. Applied and Environmental Microbiology. 15(2007)77-91. Interpretive Summary: Listeria monocytogenes is a deadly bacterium that can be acquired be eating contaminated ready-to-eat foods (such as deli meats and deli salads); thus, methods are needed to detect this bacterium in food prior to distribution and human consumption of contaminated foods. Current methods for the detection of L. monocytogenes from food lack the ability to distinguish this bacterium from the mixture of bacteria found in most foods. The most widely used methods for the detection of harmful bacteria in food utilize antibodies (the same molecules used by your immune system to clear infectious agents from your body) to impart specificity. Unfortunately, conventional methods of antibody production, involving the immunization of animals, are not useful for generation of antibodies to some harmful bacteria, including L. monocytogenes. We recently employed a new molecular method for antibody selection, called antibody phage display, to isolate an antibody that can specifically bind to L. monocytogenes. We are using the L. monocytogenes-specific antibody to develop greatly improved methods for the detection of L. monocytogenes in food. In this study we report the identification of the part of the L. monocytogenes cell to which this antibody binds (the antigen). The identification of this antigen is an important step toward the development of methods to detect this deadly bacterium from food.
Technical Abstract: A Listeria monocytogenes-specific single-chain antibody bound to a protein antigen that was present in the cellular membrane and was also secreted from the cell. The protein was identified as the actin polymerization protein by matrix-assisted laser desorption ionization–time-of-flight mass (MALDI-TOF) mass spectrometry and western immunoblot analysis. Addition of activated charcoal to the culture medium, a condition know to increase the expression of actA and other PrfA regulated virulence genes, increased the levels of ActA in several, but not all, strains of L. monocytogenes.