Two pathogenic species within the genus Neisseria cause the diseases gonorrhoea and
meningitis. While
vaccines are available to protect against four N. meningitidis serogroups, there is currently no commercial
vaccine to protect against serogroup B or against N. gonorrhoeae. Moreover, the available
vaccines have significant limitations and with antibiotic resistance becoming an alarming issue, the search for effective
vaccine targets to elicit long-lasting protection against Neisseria species is becoming more urgent. One strategy for
vaccine development has targeted the neisserial
iron import systems. Without
iron, the Neisseriae cannot survive and, therefore, these
iron import systems tend to be relatively well conserved and are promising
vaccine targets, having the potential to offer broad protection against both gonococcal and
meningococcal infections. These efforts have been boosted by recent reports of the crystal structures of the neisserial receptor
proteins TbpA and TbpB, each solved in complex with human
transferrin, an
iron binding protein normally responsible for delivering
iron to human cells. Here, we review the recent structural reports and put them into perspective with available functional studies in order to derive the mechanism(s) for how the pathogenic Neisseriae are able to hijack human
iron transport systems for their own survival and pathogenesis.