Recombinant Opc protein from Neisseria meningitidis reconstituted into liposomes elicits opsonic antibodies following immunization

The reconstitution of recombinant bacterial outer membrane proteins (OMPs) into their native conformations after purification has been the major problem in their use as effective vaccines. Liposomes have been shown to be an attractive approach, providing a native-like environment for these antigens. The meningococcal recombinant Opc (rOpc) protein, produced as inclusion bodies in Escherichia coli, was incorporated into phospholipid vesicles consisting of dipalmitoyl phosphatidylcholine and cholesterol. The incorporation of rOpc into the lipid bilayer was demonstrated, and the reconstitution of some native epitopes was tested using a set of monoclonal antibodies. Subcutaneous immunization of Balb/c mice with rOpc-containing vesicles resulted in the generation of a high level of specific antibodies. The elicited antibodies reacted with the native meningococcal protein and showed opsonic activity.