Immunogenicity of in vitro folded outer membrane protein PorA of Neisseria meningitidis

In vitro folded and the denatured form of PorA P1.6 From Neisseria meningitidis strain M990 were used for immunization studies in mice. previously. the antigen was isolated from cytoplasmic inclusion bodies, folded and purified. Its immunogenicity without adjuvant appeared to be low. The addition of the adjuvant QuilA, but not of galE lipooligosaccharide, considerably enhanced the immunogenicity. Moreover, when immunized with folded PorA P1.6 plus QuilA, a clear switch towards the IgG2a subclass of antibodies and concomitantly, the appearance of serum bactericidal activity, which is believed to be important for protective immunity, was observed. Hence, a tool for preparing vaccines against serogroup B meningococci devoid of endotoxin is available. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.