The principal findings were that i) immunization with rMafA 2/3 protein induced antibodies that were bactericidal for gonococci, ii) the most effective responses were induced with protein incorporated into liposomes or Zwittergent micelles that contained the adjuvant MPLA, iii) functional activity correlated with serum reactivity against the homologous protein and OM in ELISA, and recognition of the protein in OM western blots and on the bacterial surface using flow cytometry, and iv) anti-MafA 2/3 sera inhibited gonococcal association with human cells cultured in vitro. Here, MAFA is linked to ocular melanoma.