© 2000 Nature America Inc. • http://medicine.nature.com ARTICLES Functional genomics of Neisseria meningitidis pathogenesis YAO-HUI SUN1, SHARMILA BAKSHI1, RONALD CHALMERS2 & CHRISTOPH M. TANG1 1University Department of Paediatrics, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom 2Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom Correspondence to be addressed to C.M.T.; Email:
[email protected] and R.C.; Email:
[email protected] The pathogenic bacterium Neisseria meningitidis is an important containing unique signature tags (fig, 1b), in 96 separate trans- cause of septicemia and meningitis, especially in childhood1. The position reactions. The modified genomic DNA was repaired, establishment and maintenance of bacteremic infection is a pre- and returned to the host by transformation. We selected 30 mu- requisite for all the pathological sequelae of meningococcal in- tants from each reaction, resulting in a library of 2,880 mutants fection. To further understand the genetic basis of this essential (30 pools × 96). To determine whether Tn10 insertion occurs at step in pathogenesis, we analyzed a library of 2,850 insertional diverse sites, we assessed 40 transformants from a single trans- .com mutants of N. meningitidis for their capacity to cause systemic in- position reaction by Southern blot analysis. Each had a single, fection in an infant rat model. The library was constructed by in distinct Tn10 insertion (Fig. 1c). To establish whether Tn10 in- .nature vitro modification of Neisseria genomic DNA with the purified tegration was stable during systemic infection of infant rats, we components of Tn10 transposition2.