The pathogenic Neisseria, Neisseria meningitidis and Neisseria gonorrhoeae, are closely related bacteria that cause significant human morbidity and mortality worldwide. N. meningitidis causes meningitis and sepsis, with up to 1.2 million cases and 135,000 deaths per year worldwide. N. gonorrhoeae causes the sexually transmitted infection (STI) gonorrhoea and is associated with infertility and increased HIV transmission. There are >106 million reported cases per year worldwide, and due to increasing antibiotic resistance N. gonorrhoeae has been categorised by the CDC as an ‘urgent threat’ that requires immediate action.
These bacterial species have numerous strategies (e.g., oxidative stress defences1,2, antigenic variability3,4, host mimicry and immune evasion mechanisms5,6) that enable them to survive and cause disease within their exclusive host, the human. As such, vaccine development for these organisms has proven difficult. For serogroup B N. meningitidis (MenB), a non-traditional, genome-based, reverse vaccinology approach was used to identify vaccine targets7. The antigens present in the recently licensed multicomponent MenB vaccine (4CMenB / Bexsero®) have been characterised as important meningococcal virulence factors5,6, and will be discussed. Unfortunately, there is still no vaccine for N. gonorrhoeae and the fact that gonococcal infection does not lead to natural protection against reinfection means that novel approaches are also required to develop a vaccine against this pathogen8,9. To facilitate gonococcal development, we performed mathematical modelling of different vaccine scenarios and predicted that even a modestly efficacious vaccine could have a substantial impact on gonorrhoea prevalence and sequelae, within a relatively short time frame10. Using genome and glyco-interactome based studies we have identified candidate antigens, several of which are highly conserved, immunogenic, and important for various stages of colonisation and disease. It is likely that a combination of several antigens will be needed to protect against gonorrhoea, and we are working towards this goal.