AN ANTIBODY MODIFIED AUTOMATED ENZYME‐LINKED IMMUNOSORBENT ASSAY‐BASED METHOD FOR DETECTION OF STAPHYLOCOCCAL ENTEROTOXIN*

Abstract

ABSTRACT Studies were conducted with an automated enzyme‐linked immunosorbent assay (ELISA)‐based method (Vidas, Staph enterotoxin‐II [SET‐II]), exhibiting an antibody capture that had undergone modification by removal of the Fc fragment on the antibody. Raw liquid or shell eggs containing a nontoxin component with an attraction to the staphylococcal antienterotoxins were studied. Prior to ELISA testing, the eggs were homogenized and extracts collected by centrifugation. Studies showed that regardless of the ELISA‐based method used that utilized the unmodified antibodies with both the Fab1 + Fc fragments intact, positive (false positive) ELISA responses occurred with fertilized egg yolks and fertilized whole liquid or whole shell eggs. Conversely, when modified (Fab1) antibodies were used, the automated SET‐II enzyme‐linked fluorescent immunoassay was negative.PRACTICAL APPLICATIONSMost enzyme‐linked immunosorbent assays as well as other serological systems use the whole antibody that has not undergone modification for the detection of the staphylococcal enterotoxins. The use of whole antibody (Fab1 + Fc fragments) has on occasion produced false positive results. However, the antibody in which the Fc fragment has been removed leaving the Fab1 fragment provides a more specific antibody for the identification of this microbial toxin. The use of modified antibody (Fab1 fragment) represents significant improvement in antibody quality thus ensuring a greater degree of specificity without sacrificing the sensitivity of serological methods for the detection of staphylococcal enterotoxin in foods.