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This volume provides methods to analyze the meningococcus and its interactions with biologically relevant host cells and sites, to interrogate the population structure and biology of the meningococcus that defines its capacity to cause disease, and to aid in vaccine development and surveillance. Many of these methods are applicable to the close relative, Neisseria gonorrhoeae, and several of the methods described can also be used in investigating host-pathogen interactions for a range of other organisms. Written for the highly successful Methods in Molecular Biology series, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible protocols, and tips on troubleshooting and avoiding known pitfalls. Authoritative and practical, Neisseria meningitidis: Methods and Protocols will allow for the use of these methods by more laboratories and foster collaboration and consistency in investigations of this enigmatic and dangerous pathogen.

The well-conserved protein Hfq has emerged as the key modulator of riboregulation in bacteria. This protein is thought to function as an RNA chaperone and to facilitate base pairing between small regulatory RNA (sRNA) and mRNA targets, and many sRNAs are dependent on the Hfq protein for their regulatory functions. To address the possible role of Hfq in riboregulated circuits in Neisseria meningitidis , we generated an Hfq mutant of the MC58 strain, and the knockout mutant has pleiotropic phenotypes; it has a general growth phenotype in vitro in culture media, and it is sensitive to a wide range of stresses, including those that it may encounter in the host. Furthermore, the expression profile of a vast number of proteins is clearly altered in the mutant, and we have identified 27 proteins by proteomics. All of the phenotypes tested to date are also restored by complementation of Hfq expression in the mutant strain. Importantly, in ex vivo and in vivo models of infection the Hfq mutant is attenuated. These data indicate that Hfq plays a key role in stress response and virulence, and we propose a major role for Hfq in regulation of gene expression. Moreover, this study suggests that in meningococcus there is a large Hfq-mediated sRNA network which so far is largely unexplored.