(A) Arrangement of lav homologs in H. influenzae and N. meningitidis MC58 genomes. Neisserial genes are depicted as filled arrows (indicating orientation); H. influenzae-derived genes are depicted as open arrows. Hairpin symbols represent paired hUSs in stem-loop configuration. Relative to that in H. influenzae-Rd, the Int1 lav island is inserted within a stem-loop hUS pair, resulting in partial duplication of the hUS pair flanking the site of insertion within an Int1 ancestor. Fragments of H. influenzae holB and tmk in Neisseria are indicated in parentheses. (B) Repeat-containing regions of lav homologs in Int1 (hi lav), N. meningitidis MC58 (nm) (24, 37), N. gonorrhoeae, (ng) and biotype aegyptius (hae) reference strain R1967. (C) Inferred amino acid sequences of regions of Lav homologs, aligned with MEGALIGN (DNAStar). aa 1 to 40 are conserved sequences at the N terminus, including the predicted signal sequence cleavage site (arrow). aa 121 to 156 represent a less conserved region within the presumptive passenger domain, including a sequence bracketed by conserved cysteine residues (asterisks).