Tools for tackling meningococci that express four of the disease-associated seogroups (A, C, Y and W) are to hand in the form of protein-conjugate polysaccharide vaccines [5]. At least in the case of the meningococcal C polysaccharide conjugate (MCC) vaccines, immunisation BMN 673 in vivo of the population in which transmission is occurring can disrupt transmission to the extent that the circulation of potentially invasive organisms can be reduced to a very low level, if not completely eradicated [36] and [37]. In a number of countries this has been achieved for serogroup C meningococci,

with little convincing evidence of the replacement of these organisms with other harmful meningococci. The goal would be to eliminate serogroup A,

B, C, W, Y, and Selleck Duvelisib perhaps X capsules: more specifically this means removing from the meningococcal population the Region A variants of the cps genome region which encode the synthesis genes for these serogroups [38]. A three-phase programme for the control or elimination of invasive meningococci can be envisaged: Phase I would target serogroup A and serogroup C meningococci at the global level. Effective conjugate vaccines exist against these organisms, including the recently introduced MenAfriVac vaccine [39], developed to be affordable in sub-Saharan countries [40]. Phases I and II are feasible with current technology, if challenging from a logistical point of view. Indeed, in one of the most exciting developments in the history of meningococcal disease control, the rollout of the MenAfriVac conjugate serogroup A polysaccharide Isotretinoin vaccine presents the prospect of the end of epidemic group A meningococcal disease in sub-Saharan Africa [35]. The goal of the Meningitis Vaccine Project (MVP) was the sustainable introduction of a serogroup A conjugate polysaccharide vaccine, with the vaccine priced a less 1US$ per dose, a goal that was achieved by a novel North–South partnership of technology

transfer and manufacturing capacity [40]. Other factors aiding the elimination of serogroup A meningococci is their relative lack of genetic diversity and geographical distribution. Virtually all cases of serogroup A disease are caused by one of three clonal complexes, ST-1 complex and the closely related ST-4 and ST-5 clonal complexes [44]. This is different from sialic acid-containing serogroups B, C, W and Y which are found in numerous genetically divergent clonal complexes. Similarly, whilst the sialic acid capsules are globally distributed, much of the serogroup A disease is in Africa and Asia [9], [44] and [45], with certain regions currently experiencing little or no serogroup A disease [16].