Neisseria gonorrhoeae (Ng) is an urgent global health threat, with rising antimicrobial resistance and no licensed vaccine currently available. Multiple Ng‑based vaccine candidates are now progressing through pre‑clinical and clinical development, alongside growing interest in understanding the immune responses associated with the reduced incidence of gonorrhoea observed following vaccination with the meningococcal B vaccine 4CMenB. A major barrier to advancing these efforts is the lack of standardised, scalable immunoassays that enable comparison of vaccine‑induced immune responses across studies, strains, and geographical regions. International expert working groups have recently reached consensus that IgG binding assays based on outer membrane vesicles (OMVs) from a small, diverse panel of Ng strains represent a suitable approach for assay harmonisation.
Here we report early proof‑of‑concept data supporting the development of a multiplex OMV‑based Luminex immunoassay. Native OMVs from Neisseria meningitidis NZ98/254 and a panel of diverse Ng strains were prepared. Prior to multiplex assay development, an NIBSC reference reagent consisting of pooled human sera from individuals vaccinated with 4CMenB (NIBSC 23/108) was evaluated by ELISA for IgG binding to both meningococcal and gonococcal OMVs. As expected, strong antibody reactivity against homologous meningococcal OMVs was observed, together with clear cross‑reactive binding to gonococcal OMVs.
OMVs were subsequently conjugated to spectrally distinct Luminex beads using carbodiimide NHS‑ester chemistry and assessed in a duplex assay format. Robust antibody binding to NZ98/254 OMVs confirmed successful OMV coupling and antigen presentation. Consistent with ELISA results, clear cross‑reactive IgG binding to Ng WHO M (NCTC 13481) OMVs was also detected.
These findings demonstrate the feasibility of coupling native Neisseria OMVs to Luminex beads and support further development of a multiplex OMV‑based immunoassay. This work provides an essential early step toward establishing open‑access, standardised immunoassays to support comparability of immune responses across gonococcal and meningococcal vaccine studies. Future work will extend this platform to include OMVs from multiple globally representative Ng strains, enabling comprehensive immunogenicity assessment of multivalent vaccines in clinical trials