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Human opsonins induced during meningococcal disease recognize outer membrane proteins PorA and PorB
A K Lehmann1, A Halstensen, I S Aaberge
1Medical Department B, University of Bergen, Bergen, Norway. Anne.Lehmann@medb.uib.no
Abstract:
Human opsonins directed against specific meningococcal outer membrane structures in sera obtained during meningococcal disease were quantified with a recently developed antigen-specific, opsonin-dependent phagocytosis and oxidative burst assay. Outer membrane vesicles (OMVs) and PorA (class 1) and PorB (class 3) proteins purified from mutants of the same strain (44/76; B:15:P1.7. 16) were adsorbed to fluorescent beads, opsonized with acute- and convalescent-phase sera from 40 patients with meningococcal disease, and exposed to human leukocytes. Flow cytometric quantitation of the resulting leukocyte phagocytosis products (PPs) demonstrated that disease-induced serum opsonins recognized meningococcal OMV components and both porins. The PPPorA and PPPorB values induced by convalescent-phase sera correlated positively with the PPOMV values. However, the PPPorB values were higher than the PPPorA values in convalescent-phase sera (medians [ranges] of 754 [17 to 1,057] and 107 [4 to 458], respectively) (P < 0.0001) and correlated positively with higher levels of immunoglobulin G against PorB than against PorA as evaluated by enzyme-linked immunosorbent assay. Extensive individual variations in the anti-OMV and antiporin serum opsonic activities between patients infected by serotypes and serosubtypes homologous and heterologous to the target antigens were observed. Simultaneously measured oxidative burst activity correlated with the opsonophagocytosis, an indication that both of these important steps in the in vitro phagocytic elimination of meningococci are initiated by opsonins directed against OMV components, including PorA and PorB. In conclusion, human patient opsonins against meningococcal OMV components and in particular PorB epitopes were identified by this new method, which might facilitate selection of opsonin-inducing meningococcal antigens for inclusion in future vaccines.
Insights
Human opsonins targeting meningococcal outer membrane vesicles (OMVs) and porins were quantified during disease. Disease-induced antibodies, particularly against PorB, were identified, aiding future vaccine development.
Area of Science:
- Immunology
- Microbiology
- Vaccinology
Background:
- Neisseria meningitidis remains a significant cause of bacterial meningitis.
- Understanding host immune responses, specifically opsonins, is crucial for developing effective vaccines.
- Outer membrane vesicles (OMVs) and porins are key targets for meningococcal vaccines.
Purpose of the Study:
- To quantify human opsonins against specific meningococcal outer membrane structures during disease.
- To evaluate the role of PorA and PorB proteins in opsonophagocytosis and oxidative burst.
- To identify potential meningococcal antigens for future vaccine development.
Main Methods:
- Developed an antigen-specific, opsonin-dependent phagocytosis and oxidative burst assay.
- Used fluorescently labeled beads coated with OMVs, PorA, and PorB proteins.
- Opsonized beads with sera from 40 patients with meningococcal disease (acute and convalescent phases).
- Quantified leukocyte phagocytosis products (PPs) and oxidative burst activity via flow cytometry.
Main Results:
- Disease-induced serum opsonins recognized OMVs, PorA, and PorB.
- Convalescent-phase serum opsonin levels against PorB were significantly higher than against PorA.
- Oxidative burst activity correlated with opsonophagocytosis, indicating opsonin initiation.
- Observed significant individual variations in opsonic activity.
Conclusions:
- Human patient opsonins target meningococcal OMV components, especially PorB epitopes.
- The developed assay can identify opsonin-inducing meningococcal antigens.
- Findings may facilitate the selection of antigens for future meningococcal vaccines.