RECOMBINANT OPC MENINGOCOCCAL PROTEIN, FOLDED IN-VITRO, ELICITS BACTERICIDAL ANTIBODIES AFTER IMMUNIZATION

The meningococcal Opc protein has been expressed as inclusion bodies i n Escherichia coli. After cell disruption and successive washing of th e insoluble fraction, insoluble proteins were solubilized in presence of the chaotropic agent guanidium hydrochloride. The extract was appli ed to a Reverse Phase High Performance Liquid Chromatography (RP-HPLC) -C4 column, for further purification. The obtained recombinant Opc pro tein was refolded in vitro, by the addition of several compounds to th e resuspended solution. Over time, the progress of renaturation was te sted by immunoblot with the human monoclonal antibody LuNm03 against t he meningococcal Opc protein. LuNm03 recognizes a conformational epito pe on the native meningococcal Opc protein. Having established the opt imal conditions of renaturation, Balb/c mice were immunized to study t he humoral immune response. The humoral immune response elicited in mi ce was measured by ELISA and immunoblot, while the functional activity of these antibodies was assayed in a bactericidal test. According to our results, it was possible to obtain a recombinant Opc protein folde d in vitro, with a conformation suitable enough to generate functional antibodies in mice, capable of killing meningococci in the presence o f human complement. (C) 1997 Elsevier Science Ltd.