Journal of Microbial & Biochemical Technology

Abstract

Comparison of Antibodies Raised Against Heat- and Gamma Radiation-Killed Bacteria

Andrew G. Gehring, Glenn Boyd, Jeffrey D. Brewster, Peter L. Irwin, Donald W. Thayer and Lisa J. Van Houten

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 radiationkilled 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, heattreated, 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).