Development, characterisation and diagnostic application of monoclonal antibodies against Yersinia pestis fibrinolysin and coagulase.

A library of monoclonal antibodies (MAbs) which recognised different epitopes of Yersinia pestis fibrinolysin (Fib) was developed. These MAbs were species-specific and demonstrated no cross-reaction in indirect immunofluorescence tests (IIFT) with other gram-negative bacteria possessing plasminogen activator activity. All the MAbs provided equally high levels of immunofluorescence with pPst+ Y. pestis strains cultivated at 37 degrees C and at 28 degrees C. In all cases, the MAbs inhibited both fibrinolytic and coagulase (Coag) activities of Y. pestis in Fib-activity inhibition and coagulase-activity inhibition reactions, and reacted with 35- and 37-kDa proteins of Y. pestis in immunoblotting, demonstrating bifunctional activity possibly similar to the properties of MAbs produced by hybrid hybridomas. On the basis of these and earlier studies, the immunochemical identity of Fib and Coag, two distinct subunits of a bifunctional fusion protein whose specific functional activity depends upon the temperature factor, was established. A new rapid, cheap, strictly specific and safe dot-ELISA based on the use of MAb against Y. pestis Fib (MAb-Fib) for reliable identification of Y. pestis strains was developed. This technique has great advantages over monoclonal diagnostic kits based on the use of MAb against Y. pestis fraction I (FI) because it allows detection of plague bacilli grown at 37 degrees C as well as at 28 degrees C. This dot-ELISA will be valuable as a clinical diagnostic tool and might be applicable to field studies and plague surveillance.