Poster Presentation 25th International Pathogenic Neisseria Conference 2026

Antigenicity in mice of multiple antigen peptides containing B-cell/T-cell epitopes of the Neisseria gonorrhoeae MafA 2/3 protein (#027)

Michael M. Girgis 1 2 , Daysiane de Oliveira 3 , Ravi Kant 4 , Christopher J McCormick 1 , Ricardo Andrez Machado-de-Avila 3 , Myron Christodoulides 1
  1. Neisseria Research Group, Molecular Microbiology, School of Clinical and Experimental Sciences, , Faculty of Medicine, University of Southampton,, Southampton, , UK
  2. Department of Microbiology & Immunology,, Faculty of Pharmacy, Manosura University, , Manosura, , Egypt
  3. Programa de Pós Graduação em Ciências da Saúde, , Universidade do Extremo Sul Catarinense, Criciúma, , Santa Catarina, , Brazil.
  4. Faculty of Applied Sciences & Biotechnology, , Shoolini University, , Solan, , Himachal Pradesh , India.
There are currently no licensed prophylactic vaccines against gonorrhoea, a sexually transmitted infection caused by the Gram-negative pathogen Neisseria gonorrhoeae. Increasing antimicrobial resistance highlights the urgent need for alternative preventive strategies. In this study, we assessed the antigenicity and functional immune responses elicited by a recombinant MafA 2/3 outer membrane protein (OMP) and two synthetic multiple antigen peptides (MAPs) incorporating predicted B- and T-cell epitopes of MafA 2/3. B- and T-cell epitopes were identified in silico, and MAP octamer peptides (MafA 2/3 MAP‑A and MAP‑B) were synthesised. Peptides were computationally docked with mouse and human MHC class II molecules to support epitope presentation. BALB/c mice were immunised with MAP‑A or MAP‑B formulated in saline, alum, SAS, or TitreMax adjuvants. Antibody responses were evaluated by ELISA against homologous and heterologous MAPs, recombinant MafA 2/3 protein, and outer membranes (OM) from N. gonorrhoeae strains P9‑17, FA1090, and 12CFX_T_039 (AR205). Antisera were further examined by western blotting, flow cytometry using intact gonococci, and serum bactericidal assays. Immunisation with both MAP‑A and MAP‑B induced peptide- and OM-reactive antibodies detectable by ELISA, western blotting, and flow cytometry, irrespective of adjuvant formulation. Antibodies recognised outer membrane components and bound to the surface of whole gonococci. Functional activity was limited, with weak complement-mediated bactericidal activity observed only against the homologous strain P9‑17 (50% titre of 4) and no detectable killing of heterologous strains. These findings demonstrate that MafA 2/3 MAP peptides are antigenic in mice and capable of inducing strain-specific functional antibodies. Although bactericidal activity was modest, this synthetic epitope-based strategy adds to the limited repertoire of experimental gonococcal vaccine approaches and warrants further optimisation to enhance breadth and protective efficacy.
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