Expression of fHbp v.1 and v.2 in OMV vaccines prepared from LpxL1 KO mutants of strain NZ98/254. Primary antibodies were anti-fHbp MAbs JAR 5, which is specific for fHbp v.1 (2, 3, 41), and JAR 11, which is specific for fHbp v.2 (2, 3). NZ98/254 LpxL1 KO, native OMV from mutants of NZ98/254 with inactivated LpxL1; WT v.1, mutant expressing only endogenous wild-type fHbp v.1; KO v.1, mutant with inactivated gene encoding fHbp v.1; Mutant v.1+v.2, mutant with both endogenous fHbp v.1 and heterologous fHbp v.2; rfHbp, recombinant fHbp v.1 or v.2.