| Summary: | <p>Abstract</p> <p>Background</p> <p><it>In vitro </it>studies with cell line infection models are beginning to disclose the strategies that <it>Neisseria meningitidis </it>uses to survive and multiply inside the environment of the infected host cell. The goal of this study was to identify novel virulence determinants that are involved in this process using an <it>in vitro </it>infection system.</p> <p>Results</p> <p>By using reverse transcriptase-PCR differential display we have identified a set of meningococcal genes significantly up-regulated during residence of the bacteria in infected HeLa cells including genes involved in L-glutamate transport (<it>gltT </it>operon), citrate metabolism (<it>gltA</it>), disulfide bond formation (<it>dsbC</it>), two-partner secretion (<it>hrpA-hrpB</it>), capsulation (<it>lipA</it>), and DNA replication/repair (<it>priA</it>). The role of PriA, a protein that in <it>Escherichia coli </it>plays a central role in replication restart of collapsed or arrested DNA replication forks, has been investigated. <it>priA </it>inactivation resulted in a number of growth phenotypes that were fully complemented by supplying a functional copy of <it>priA</it>. The <it>priA</it>-defective mutant exhibited reduced viability during late logarithmic growth phase. This defect was more severe when it was incubated under oxygen-limiting conditions using nitrite as terminal electron acceptors in anaerobic respiration. When compared to wild type it was more sensitive to hydrogen peroxide and the nitric oxide generator sodium nitroprusside. The <it>priA</it>-defective strain was not affected in its ability to invade HeLa cells, but, noticeably, exhibited severely impaired intracellular replication and, at variance with wild type and complemented strains, it co-localized with lysosomal associated membrane protein 1.</p> <p>Conclusion</p> <p>In conclusion, our study i.) demonstrates the efficacy of the experimental strategy that we describe for discovering novel virulence determinants of <it>N. meningitidis </it>and ii.) provides evidence for a role of <it>priA </it>in preventing both oxidative and nitrosative injury, and in intracellular meningococcal replication.</p>
|
|---|
