|THAYER, DONALD - Retired ARS Employee|
|VAN HOUTEN, LISA - Retired Non ARS Employee|
Submitted to: Journal of Microbial and Biochemical Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2012
Publication Date: 12/26/2012
Citation: Gehring, A.G., Boyd, G., Brewster, J.D., Irwin, P.L., Thayer, D.W., Van Houten, L.J. 2012. Comparison of antibodies raised against heat-and gamma radiation-killed bacteria. Journal of Microbial and Biochemical Technology. DOI 10.4172/1948-5948.S2-004.
Interpretive Summary: Antibodies, the same natural protein molecules that our bodies use to fend off invasion by foreign particles, are used in many tests for the rapid detection of specific bacteria in processed foods. Although the detection of specific bacteria may be achieved, the ability to distinguish between bacteria that are either alive (and may pose a threat to the consumer) or dead (perhaps as a consequence of a processing step) is not expected to be learned using such tests. In this investigation, antibodies were custom made to recognize live and dead (killed by either high temperature or irradiation) bacteria. Both sets of antibodies were demonstrated to highly react with the bacteria killed by high temperature whereas a poor reaction was observed with the live bacteria. The bacteria killed by irradiation elicited a moderate response with either antibody set. Using this information, accurate tests may be developed for assessing not only the extent but also the potential hazard, with respect to proliferation, of bacterial contamination in food products.
Technical Abstract: For antibody generation, pathogenic bacteria are often heat-treated prior to inoculation into host animals in order to prevent infection and subsequently, premature death of the host. Inoculation of host rabbits with gamma radiation-killed pathogenic bacteria was employed with the hopes of generating antibodies that would have higher affinity, relative to antibodies raised against thermally denatured microorganisms, to live pathogens. The two antibody sets, raised against either heat-killed or irradiated bacterial cells, were compared for immunological response with live, heat-treated, chemically-treated (i.e., bleached), and irradiated Escherichia coli O157:H7 and Salmonella bacteria. With the exception of the chemically-treated cell immunological response, both antibody sets yielded similar responses—low for irradiated cells, moderate for live cells, and high for heat-treated cells. The results suggested that thermal or chemical treatment of live pathogen containing food samples will elicit higher immunological responses with either antibody system, indicating potential application for detection of the presence of live bacteria in non-irradiated food systems. In addition, these findings also indicated that an immunoassay analysis of irradiated foods may lead to low signals that might be interpreted as indicating the presence of live cells (i.e., may lead to a false negative result).