Immunogeneity and structural organisation of some pLCR-encoded proteins ofYersinia pestis

A novel method of cultivation of Yepsinia pestis EV-76 and its isogenic str ains KM-217 (pPst(-);pCad(+);pFra(-)) and KM-218 (pPst(-);pCad(-);pFra(-)) and careful extraction of Y. pestis proteins (YPPs) permitted isolation of >35 low Ca2+ response plasmid (pLCR)-encoded products, some of which are po tentially new members of the LCR family. Immunisation with each YPP demonst rated that 25-, 54-, 72- and 87-kDa YPPs provided the highest level of prot ection in mice challenged with Y. pestis virulent strain 231. Their immunol ogical relationship was established with monoclonal antibodies (MAbs) and r evealed several common properties, including oligosaccharide binding with s pecificity for N-acetylglucosamine. Affinity chromatography with MAb to the 25-kDa YPP permitted purification of the relevant antigen and its precurso r. Their existence in the form of a complicated protein molecule was shown.