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Neisseria meningitidis (the meningococcus) is a member of the normal nasopharyngeal microbiome in healthy individuals, but can cause septicemia and meningitis in susceptible individuals. In this chapter we provide an overview of the disease caused by N. meningitidis and the schemes used to type the meningococcus. We also review the adhesions, virulence factors, and phase variable genes that enable it to successfully colonize the human host. Finally, we outline the history and current status of meningococcal vaccines and highlight the importance of continued molecular investigation of the epidemiology and the structural analysis of the antigens of this pathogen to aid future vaccine development.

Escherichia coli has been engineered to produce chlorophyll., Chlorophylls are essential cofactors for photosynthesis, which sustains global food chains and oxygen production. Billions of tons of chlorophylls are synthesized annually, yet full understanding of chlorophyll biosynthesis has been hindered by the lack of characterization of the Mg–protoporphyrin IX monomethyl ester oxidative cyclase step, which confers the distinctive green color of these pigments. We demonstrate cyclase activity using heterologously expressed enzyme. Next, we assemble a genetic module that encodes the complete chlorophyll biosynthetic pathway and show that it functions in Escherichia coli. Expression of 12 genes converts endogenous protoporphyrin IX into chlorophyll a, turning E. coli cells green. Our results delineate a minimum set of enzymes required to make chlorophyll and establish a platform for engineering photosynthesis in a heterotrophic model organism.

The development of prophylactic vaccines against pathogenic bacteria is a major objective of the World Health Organisation. However, vaccine development is often hindered by antigenic diversity and the difficulties encountered manufacturing immunogenic membrane proteins. Here, we employed structure-based design as a strategy to developChimericAntigens (ChAs) for subunit vaccines. ChAs were generated against serogroup BNeisseria meningitidis(MenB), the predominant cause of meningococcal disease in the Western hemisphere. MenB ChAs exploit the lipoprotein factor H binding protein (fHbp) as a molecular scaffold to display the immunogenic VR2 epitope from the integral membrane protein PorA. Structural analyses demonstrate fHbp is correctly folded and that PorA VR2 epitope adopts an immunogenic conformation. In mice, ChAs elicit antibodies directed against fHbp and PorA, with antibody responses correlating to protection against meningococcal disease. ChAs offer a novel approach for generating multivalent subunit vaccines, containing of epitopes from integral membrane proteins, whose composition can be selected to circumvent pathogen diversity.