THE ANTIBODY-RESPONSE TO A PROTOTYPE LIPOSOME VACCINE CONTAINING NEISSERIA-MENINGITIDIS OUTER-MEMBRANE PROTEIN P1 PRODUCED IN BACILLUS-SUBTILIS

Monoclonal antibodies to the class 1 outer membrane protein P1 of Neis seria meningitidis B:15:P1.7,16 have been shown to be bactericidal and protective in an infant rat meningitis model. We have produced the P1 protein in Bacillus subtilis as inclusion bodies. When the purified a nd denatured protein (BacP1) was reconstituted with phosphatidylcholin e into liposomes, native antigenic epitopes were formed. Such liposome s were reproducibly immunogenic in mice and guinea pigs at a low dose (1-10 mu g of BacP1 protein) and without any other adjuvant. The resul ting antisera contained high titers (enzyme immunoassay) of antibodies directed to native P1 epitopes exposed on the surface of meningococca l cells. The sera were also active with live N. meningitidis in bacter icidal assays and protective in the infant rat meningitis model; all t hese activities were specific to the serosubtype of the P1 protein.