SIMPLIFIED PURIFICATION OF LISTERIA-MONOCYTOGENES LISTERIOLYSIN-O ANDPRELIMINARY APPLICATION IN THE ENZYME-LINKED-IMMUNOSORBENT-ASSAY (ELISA)

A simplified procedure was developed for purification of listeriolysin O (LLO) of Listeria monocytogenes, consisting of hydroxylapatite adso rption chromatography followed by Sepharose S ion exchange chromatogra phy. The LLO (58 kDa) appeared pure in terms of sodium dodecylsulfate polyacrylamide electrophoresis and immunoblots with polyclonal rabbit immune sera. The purified LLO could be stored at -65 degrees C for 1 y ear without loss of immunoreactivity. Similarly, flat-bottom microtite r strips from two vendors that had been charged with LLO, could be sto red at -65 degrees C for up to 3 months without loss of LLO. Three pat ients with documented listeriosis developed elevated IgG titres agains t LLO; 2 of the patients revealed minimally raised IgM titres, as dete rmined with the enzyme-linked immunosorbent assay.