Conserved lipoproteins of pathogenic Neisseria species bearing the H.8 epitope: lipid-modified azurin and H.8 outer membrane protein.

Many of the surface components of the pathogenic Neisseria species demonstrate marked antigenic variability, both between different strains and among variants of a single strain. Numerous examples of such variable surface components are described in the other reviews in this issue. Amid this surface variability, there are relatively few components or antigens that are conserved among all gonococci or meningococci, or both. The conserved antigens that have been identified have been the subject of considerable study in an effort to determine whether they play a direct role in neisserial pathogenesis and whether they might be targets of a protective immune response. The existence of a protein epitope that is conserved among pathogenic Neisseria species was revealed by the binding of a monoclonal antibody (MAb) designated H.8 (8), as well as other MAbs with similar specificities (14, 31). These MAbs bind to all gonococci and meningococci that have been tested and to N. lactamica and N. cinerea strains, but not to strains of other commensal Neisseria species (1, 8, 14, 31). There has been much recent progress in identifying and characterizing the proteins that are recognized by H.8-specific MAbs, particularly through the use of recombinant deoxyribonucleic acid (DNA) approaches. The existence of multiple proteins that bind H.8-specific MAbs was revealed by screening libraries of gonococcal and meningococcal genes. Gotschlich et al. (11) cloned two distinct gonococcal genes that hybridize to each other in Southern blotting experiments and encode H.8 MAb-binding proteins with similar apparent molecular weights. Further analysis of these and other cloned genes has added to our understanding of the characteristics of two different proteins that are recognized by H.8-specific MAbs: the lipid-modified azurin and the H.8 outer membrane protein (designated [,aZ and Lip, respectively, in the nomenclature recommendations included in this issue).