Serum bactericidal antibody responses of mice immunized with vaccine mixtures. The vaccine groups were native OMVs from LpxL1 KO mutants of H44/76 and NZ98/254 expressing fHbp v.1 and v.2 (MNM-OMV), detergent-treated OMVs from the indicated wild-type strains (Detergent OMV, WT), and recombinant fHbp v.1 and 2 (rfHbp v.1 + v.2). (A) GMTs against wild-type strains used to prepare mutants for the native OMV vaccines. P1.7-2,4 and P1.7,16 refer to the variable region sequence types of the respective PorA proteins of the test strains. (B and C) Reverse cumulative distributions of bactericidal titers against strains expressing PorA proteins heterologous to those of the vaccine strains and fHbp in the antigenic v.1 group (eight strains) (B) or v.2 and v.3 groups (six strains) (C). The eight v.1 strains and six v.2 or v.3 strains are described in Table 1. SE, standard error.