Studies on the pathogenic Neisseria: Characterization of H.8 lipoproteins and identification of a mouse genetic locus (Lps) affecting susceptibility to meningococcal infection

The pathogenic bacterial species Neisseria gonorrhoeae and N. meningitidis express an outer membrane lipoprotein recognized by monoclonal antibody H.8. Most commensal Neisseria species do not express the H.8 OMP. A cloned gonococcal H.8 OMP gene was subcloned and sequenced. The predicted protein contained a consensus lipoprotein signal sequence processing site, and the mature protein consisted of 71 amino acids containing 13 repeats of the pentamer ala-ala-glu-ala-pro (AAEAP). A mutant lacking the H.8 OMP was constructed using transposon mutagenesis of the cloned gene in E. coli followed by transformation of the parental gonococcal strain.; A second gene cloned from both the gonococcus and the meningococcus encodes a protein containing a consensus lipoprotein signal sequence processing site, a N-terminal domain consisting of five imperfect AAEAP repeats, and a C-terminal domain highly homologous to the sequence of azurins, proteins that function in electron transport in other bacteria. The cloned meningococcal azurin gene encoded a lipoprotein as shown by {dollar}sp{lcub}14{rcub}{dollar}C-palmitate incorporation and inhibition of processing by globomycin. The C-terminal azurin domain encoded by the cloned gene was recognized by polyclonal anti-azurin serum. Commensal as well as pathogenic Neisseria expressed a product recognized by anti-azurin serum and bound an oligonucleotide probe specific for the 3{dollar}spprime{dollar}, azurin domain-encoding region of the cloned gene.; Administrations of monoclonal antibody directed against the H.8 OMP did not protect mice from meningococcemia. However, murine resistance to meningococcemia was nonspecifically enhanced by exdotoxin.; In a panel of widely unrelated inbred mouse strains, only mice with the Lps{dollar}sp{lcub}rm d{rcub}{dollar} (defective endotoxin response) genotype were highly susceptible to meningococcemia. Lps{dollar}sp{lcub}rm d{rcub}{dollar} mice experienced a greater magnitude and duration of meningococcemia than coisogenic Lps{dollar}sp{lcub}rm n{rcub}{dollar} (normal endotoxin response) mice. This difference was due to a Lps-influenced cellular response, and probably a macrophage-mediated effector mechanism. The relative resistance of Lps{dollar}sp{lcub}rm n{rcub}{dollar} mice was eliminated by the macrophage-ablative agent dextran sulfate but was not affected by lymphocyte-ablative irradiation. Lps{dollar}sp{lcub}rm n{rcub}{dollar} spleen cells limited meningococcal growth in vitro better than Lps{dollar}sp{lcub}rm d{rcub}{dollar} spleen cells. The macrophage defect exploited by meningococci was specific to the Lps{dollar}sp{lcub}rm d{rcub}{dollar} genotype. Meningococcal strains differed in the ability to exploit the Lps{dollar}sp{lcub}rm d{rcub}{dollar} genotype of the mouse.