Development of a cloth-based enzyme-linked immunosorbent assay

A cloth-based enzyme immunoassay (CEIA) for the direct detection of microbial antigens in test samples was developed. The assay has its basis in the adsorption of antibodies on a variety of cloth surfaces, which can subsequently be used to capture antigens. The captured antigens are then detected by use of an enzymeantibody conjugate. The assay is a simple procedure which has produced negligible signals for negative controls. As a model CEIA system, the detection of Brucella abortus (the causative agent of brucellosis in cattle) was studied. Whole antiserum was diluted, heated at 75 C for 10 min, and used to coat nonwoven polypropylene cloth. The CEIA was able to detect 0.3 nanograms of B. abortus lipopolysaccharide and 1.2 X 10 B. abortus cells. The CEIA was successfully adapted for the detection of bovine viral diarrhea antigen. Finally, a complement CEIA was developed for the detection of B. abortus. Guinea pig complement was adsorbed on a polyethylenimine-coated cotton cloth surface, which then served to capture immune complexes formed when a test antigen sample was mixed v/ith enzyme labeled antibody. This form of the CEIA had a lower detectability than the direct assay, but was simpler to perform since it only required one incubation step.