ELISA detectable virulence marker antigen of enteroinvasive Escherichia coli is coded by a 140 megadalton plasmid.

The ELISA reactive virulence marker antigen, characteristic of enteroinvasive Escherichia coli and virulent Shigella, expressed in an E. coli K-12 recipient after the 140 Md plasmid of an enteroinvasive E. coli strain had been introduced into it. Similarly to the epithelial cell penetration and Congo red binding capacities--known to be coded by the above plasmid--the virulence marker antigen expressed also only at 37 degrees C but not at 30 degrees C. These data suggest the plasmid coded nature of the virulence marker antigen.