IDENTIFICATION OF SHIGELLA AND ENTEROINVASIVE ESCHERICHIA-COLI STRAINS BY A VIRULENCE-SPECIFIC, MONOCLONAL ANTIBODY-BASED ENZYME-IMMUNOASSAY

BALB/c mice were immunised with water extracts made from an Escherichi a coli K-12 strain harbouring the shigella invasion plasmid, and hybri domas secreting antibodies specific to invasion plasmid-coded antigens were selected. On Western blots, antibodies produced by one of these clones (MAIC-1) recognised a protein of 43 kDa, which is the molecular mass of invasion plasmid coded antigen C (IpaC). When used in enzyme immunoassay against whole bacterial cells or against proteins secreted by actively growing bacteria, MAIC-1 clearly differentiated between i nvasive and non-invasive strains. Testing 123 enteroinvasive and 139 n on-enteroinvasive strains the MAIC-1-based assay proved to be highly s pecific and sensitive in recognising enteroinvasive isolates. This tes t could be an inexpensive and rapid alternative to cumbersome virulenc e assays and a helpful technique in identifying Shigella or enteroinva sive Escherichia coli isolates.