Phylogenetic tree inferred from aligned tbpB genes. Over 500 trees were generated using Clonalframe from which a 95% majority-rule consensus tree was derived and imported into MEGA version 4.0 for further annotation. Meningococcal reference tbpB genes (accession numbers in brackets) belonging to isolates B16B6, M982, 2713, 2717, 8710, 8680, FA19, FA1090, FAM18, Z2491 and MC58 [Genbank: Z15129, Z15130, AJ223044, AJ279554, Y09618, Y09977, U05205, U65219, AM421808, AL157959 and AE002098, respectively] were also included in the phylogenetic analysis. The proposed nomenclature for each tbpB family is indicated by large encircled letters. The nodes 1, 2 and 3 depicted with a diamond correspond to the recombination events presented in Figure 2. Open squares denote N. gonorrhoeae tbpB sequences, open circles N. lactamica, open triangles all of the other Neisseria spp. excluding N. polysaccharea, which are depicted with black circles and N. meningitidis which are represented by black squares.