HYPEREXPRESSION OF LISTERIOLYSIN IN THE NONPATHOGENIC SPECIES LISTERIA-INNOCUA AND HIGH-YIELD PURIFICATION

Listeriolysin, the hemolysin of the pathogenic species Listeria monocy togenes, was expressed in the non-pathogenic species Listeria innocua. Coexpression of the positive regulatory factor prfA in the plasmid ve ctor in conjunction with the structural gene hly increased the express ion over 500-fold. Purification from supernatant fluids was achieved b y two steps of ion exchange chromatography. The procedure resulted in over 60% yield of a hemolytically active, homogenous 58 kDa protein wh ich was used to produce monospecific antibodies. As shown by immunoblo t the purified listeriolysin was free of p60, a highly immunogenic pro tein of similar size also produced by Listeria spp., which otherwise w ould interfere with immunoassays. Listeriolysin retained full activity for more than 6 months at - 70 degrees C.