DEVELOPMENT OF A DIAGNOSTIC-TEST FOR YERSINIA-PESTIS BY THE POLYMERASE CHAIN-REACTION

A 501 bp caf1 gene fragment and a 443 bp of pla gene fragment carried by 100 kb (pFra) and 10 kb (pPst) species-specific extrachromosomal re plicons, respectively, were used as targets to study the conditions un der which DNA amplification by polymerase chain reaction (PCR) may be applied to detect and identify Yersinia pestis DNA in cell lysates of pure cultures and biological samples. The sensitivity limit of PCR wit h the crude cell lysates of Y. pestis EV was estimated as 10-50 cfu in reaction mixture. When target Y. pestis EV cells were mixed with fres h blood of white mice, which contained 0.4% potassium citrate, the PCR detection level varied from 400 to 100 cfu ml(-1) of blood depending on the method used for preparing the sample. In our tests PCR was effe ctive for the detection of yersinia in the blood of white laboratory m ice experimentally infected with virulent Y. pestis KM638 strain. This method can be considered convenient for routine detection and identif ication of Y. pestis.