Measurement of the human immune response to meningococcal lipooligosaccharide antigens by using serum to inhibit monoclonal antibody binding to purified lipooligosaccharide

Abstract

We developed a human inhibition monoclonal enzyme-linked immunosorbent assay (HIMELISA) to investigate the human immune response to the lipooligosaccharides (LOS) of Neisseria meningitidis. Monoclonal antibodies (MAb) were used to define seven epitopes on four LOS molecules of a meningococcal strain (126E) previously shown to express immunogenic LOS epitopes. The assay could distinguish epitope-specific antibody within whole sera. Neither the specificity nor the amount of the antibody measured by HIMELISA in sera of vaccinates changed during the immune response to meningococcal capsular polysaccharides, a chemically unrelated antigen. By using the HIMELISA, it was determined that sera from adults convalescing from meningococcal disease strongly inhibited MAb binding to two of the seven defined epitopes. The 3.6-kilodalton LOS of strain 126E expressed both of these epitopes. In addition, one of the inhibited epitopes was also expressed on the 4.0-kilodalton LOS of strain 126E. The convalescent-phase sera inhibited MAb binding to these two epitopes when they were expressed on LOS of diverse meningococcal strains. An acute-phase serum blocked MAb to the two epitopes to a lesser degree than did a convalescent-phase serum from the same patient. Immunoblotting the sodium dodecyl sulfate-polyacrylamide gel electrophoresisseparated LOS with convalescent-phase sera confirmed the specificity of the human anti-LOS antibody identified by HIMELISA.

Mannose-Binding Lectin Binds to Two Major Outer Membrane Proteins, Opacity Protein and Porin, ofNeisseria meningitidis

“…All washes were with TBS. A positive control membrane was incubated in the LOS-specific mAb D6A (41,42). A negative control membrane was incubated as described, but without MBL.…”

Meningococcal group A lipooligosaccharides (LOS): preliminary structural studies and characterization of serotype-associated and conserved LOS epitopes

“…MAb D6A bound LOS from representative LOS serotypes common to group A meningococci (L8 to LI I; L12 was not tested). MAb D6A also bound LOS from group B and C meningococci of serotypes LI, L3,7, and L8 as well as some LOS from other Neisseria species (6,21,22) (see also Materials and Methods). In these experiments, MAb D6A bound major or minor LOS components that were primarily of low molecular masses (usually less than ca.…”

The (α2→8)-Linked Polysialic Acid Capsule and Lipooligosaccharide Structure Both Contribute to the Ability of Serogroup BNeisseria meningitidisTo Resist the Bactericidal Activity of Normal Human Serum

“…For the Hep 2 (GlcNAc)3KDO 2 3lipid A mutants, killing was largely mediated by an antibody-initiated classical complement pathway, since killing was not observed in hypogammaglobulinemic sera. Bactericidal antibodies to conserved inner core LOS structures are found in sera of meningococcal carriers, in convalescent sera of patients following meningococcal disease, and in NHS (10,12). The NHS used in this study contained antibodies which recognized the minimal LOS structure, Hep 2 (GlcNAc)3KDO 2 3lipid A (data not shown).…”

“…LOS epitopes are immunogenic in infants and children and induce protective bactericidal antibodies in convalescent sera (10,12). These bactericidal LOS antibodies appear to be directed at conserved low-molecular-weight LOS epitopes (10,12).…”

“…LOS epitopes are immunogenic in infants and children and induce protective bactericidal antibodies in convalescent sera (10,12). These bactericidal LOS antibodies appear to be directed at conserved low-molecular-weight LOS epitopes (10,12). LOS is also a component of new serogroup B outer membrane vesicle (OMV) vaccines and is proposed as a basis for other new meningococcal vaccines (1)(2)(3)50).…”