Molecular analysis of virulence determinants of neisseria gonorrhoeae

Gonococcal virulence is thought to rely on multiple phenomena to which antigenic variation of surface proteins as well as the production of an extracellular protease specific for human IgA1 can be accounted. The expression of pilin and opacity (Op) protein in Neisseria gonorrhoeae can be switched on and off and a single cell apparently has a whole repertoire of genes to express many serologically distinguishable protein types. In order to investigate the molecular mechanisms associated with this surface variability, we have cloned the genes for pilin and Op expression in Escherichia coli. Using these genes as probes in DNA filter hybridizations, we revealed two complex gene systems which undergo genomic reorganizations and/or gene conversions which occur concomitant to changes in the expression of these surface proteins. To study the role of IgA proteases in bacterial pathogenesis, we cloned the IgA protease gene of N. gonorrhoeae MS11. This clone promotes expression and extracellular secretion of active enzyme in E. coli and other gram-negative bacterial species