Identification of regions of the chromosome of Neisseria meningitidis and Neisseria gonorrhoeae which are specific to the pathogenic Neisseria species

Neisseria meningitidis and Neisseria gonorrhoeae give rise to dramatically different diseases. Their interactions with the host, however, do share com mon characteristics: they are both human pathogens which do not survive in the environment and which colonize and invade mucosa at their port of entry . It is therefore likely that they have common properties that might not be found in nonpathogenic bacteria belonging to the same genetically related group, such as Neisseria lactamica, Their common properties may be determin ed by chromosomal regions found only in the pathogenic Neisseria species. T o address this issue, we used a previously described technique (C. R Tinsle y and X. Nassif, Proc. Natl, Acad, Sci, USA 93:11109-11114, 1996) to identi fy sequences of DNA specific for pathogenic neisseriae and not found in N. lactamica. Sequences present in N. lactamica were physically subtracted fro m the N. meningitidis Z2491 sequence and also from the N. gonorrhoeae FA109 0 sequence. The clones obtained from each subtraction were tested by Southe rn blotting for their reactivity with the three species, and only those whi ch reacted with both N. meningitidis and N. gonorrhoeae (i.e., not specific to either one of the pathogens) were further investigated. In a first step , these clones were mapped onto the chromosomes of both N. meningitidis and N. gonorrhoeae, The majority of the clones were arranged in clusters exten ding up to 10 kb, suggesting the presence of chromosomal regions common to N. meningitidis and N. gonorrhoeae which distinguish these pathogens from t he commensal N. lactamica, The sequences surrounding these clones were dete rmined from the N. meningitidis genome-sequencing project, Several clones c orresponded to previously described factors required for colonization and s urvival at the port of entry, such as immunoglobulin A protease and PiIC, O thers were homologous to virulence-associated proteins in other bacteria, d emonstrating that the subtractive clones are capable of pinpointing chromos omal regions shared by N. meningitidis and N. gonorrhoeae which are involve d in common aspects of the host interaction of both pathogens.