HEMOGLOBIN AS A CAPTURE AGENT FOR LIPOPOLYSACCHARIDE ANTIGENS IN THE ENZYME-IMMUNOASSAY OF GRAM-NEGATIVE BACTERIA

The affinity of hemoglobin for lipopolysaccharides (LPS) was exploited in its use as an inexpensive capture agent for LPS antigens in the en zyme immunoassay (EIA) of Gram negative bacteria. Two EIA formats were examined. In one, the macroporous solid phase Polymacron(TM) coated w ith hemoglobin was used to capture cholate-heat extracted LPS antigens from broth cultures of representative Gram negative bacteria, includi ng different Salmonella serotypes, which were then detected immunoenzy matically using specific antibodies. This provided a rapid, simple and inexpensive dot blot assay for these bacteria which minimized the req uirement for laboratory equipment. In another format, a microtiter pla te ELA was developed in which cholate-heat extracted Salmonella LPS an tigens were captured in hemoglobin-coated wells. The microtiter plate format is automatable and will therefore be useful in laboratories wit h high sample throughputs. While most of the results reported here foc us on the detection of Salmonella spp., we also demonstrate the applic ability of this system in the assay of Escherichia coli O157 LPS antig ens.